How to Make and Use a High-Performing Post-Consumer LDPE DensifierMany preconceptions revolve around the use of densified LDPE, the result of careless production and uses with expectations too highThe LDPE waste that comes from plastic waste from separate waste collection should be a selection of plastic films, single product, to be sent for recycling. In reality, many times, these waste streams can contain different materials, in the form of other plastics and pollutants, such as labels , paper and other fractions. The lack of a real reference market in the sale of densified LDPE leads the recycling industry to prefer granulation of the material trying, in the extrusion phase, to reduce these foreign bodies in order to best qualify the raw material. In this case, a priori, we give up paying more attention to the selection and desification phase of the LDPE waste. The result, often, is a granule that remains at the low end of the market, which can be used for molding non-metallic articles. aesthetic, such as vases and tubs for the fruit and vegetable sector, but hardly lends itself to the production of films with thin thicknesses or the production of tubes. At this point, sometimes, one wonders whether it is not better to qualify the densified material for the injection molding sector, rather than spending time, money and energy to granulate LDPE. To follow this path it is necessary to better qualify the densified, so that its use in presses does not make you regret the injection process with a filtered granule. But let's see what densified LDPE is The term “densified”, in relation to LDPE, refers to the polymer that has been compacted, in the context of mechanical recycling. The production of LDPE densified from post-consumer waste is an integral part of the recycling process of this material. The production process can be divided into these phases: - LDPE waste is acquired from designated collection points, which deal with waste from separate collection, - Once it arrives at a recycling plant, LDPE waste is separated from other materials. This separation can be done manually or through machines such as air separators. - The LDPE waste is then washed to remove impurities such as food residue, soil or other contamination. This ensures that the final product is of good quality. - After cleaning, the LDPE is shredded into small pieces or flakes. This facilitates the densification process. - There are several techniques to densify LDPE: - By agglomeration: the ground LDPE is exposed to heat and agitation. This causes the partial melting of the pieces, which agglomerate forming larger lumps. - By compaction: The process involves the use of compacting machines that press the material into blocks or agglomerates. It is important to underline that the quality of the LDPE densified largely depends on the purity of the starting material and the effectiveness of the cleaning and separation processes. Therefore, special attention is given to these steps to ensure that the densified product is of good quality and free from significant contamination. How to create a high-performance compound with densified LDPE LDPE (Low Density Polyethylene) is often used in combination with other plastic resins, to exploit the complementary characteristics of the different polymers and obtain products with specific properties. However, the decision to blend post-consumer LDPE with other polymers depends on various factors, including the desired properties of the final product, the compatibility of the polymers themselves, and the presence of compatibilizers. Let's see some combinations: - HDPE (High Density Polyethylene): LDPE and HDPE are often compatible with each other and can be mixed to obtain products with intermediate properties between the two. For example, a blend of LDPE and HDPE might offer a combination of flexibility and strength. - EVA (Ethylene Vinyl Acetate): The addition of EVA to LDPE can improve the toughness and elasticity of the product the final. EVA is also used to improve the UV resistance and flexibility of LDPE. - PP (Polypropylene): Although polypropylene and polyethylene are not intrinsically compatible, they can be mixed in the presence of specific compatibilizers. This blend can be used in specific applications where you want to combine the properties of both polymers. - LLDPE (Linear Low Density Polyethylene): LDPE and LLDPE can be mixed to adjust the mechanical properties and the workability of the final product. Care should however be taken because not all plastics are compatible with each other, and mixing incompatible polymers can lead to products with unwanted or inadequate properties. Furthermore, the presence of contaminants or additives in post-consumer materials can influence the compatibility and properties of the mixed product.What are the melting temperatures ideal for producing finished products in LDPE LDPE (Low Density Polyethylene) has a branched structure, which means that it does not have the same arrangement regular and ordered molecular chains like other polyethylenes, for example HDPE (High Density Polyethylene). This branched structure makes LDPE more flexible but also less dense and with a lower melting point than HDPE. The melting temperature of LDPE generally varies between 105°C to 115°C (220°F to 240°F). However, when it comes to transforming LDPE through techniques such as extrusion or injection molding, temperatures can vary depending on the specific needs of the application and the presence of any additives. Here are some general guidelines for processing LDPE - Extrusion: 150°C to 220°C (300°F to 430°F). - Injection molding: 140°C to 250°C (285°F to 480°F). These temperatures are general guidelines only and may vary based on LDPE waste, machine conditions and other factors. What physical characteristics does the addition of a densified LDPE product in a compound with PP bring? Mixing LDPE (Low Density Polyethylene) and PP (Polypropylene) is a common practice in some applications, especially when you want to take advantage of the complementary properties of both polymers. The addition of a densified LDPE in a compound with PP can influence the physical characteristics of the blend in various ways: Compatibility First, it is essential to note that LDPE and PP are not inherently compatible. This means that without the use of compatibilizers or modification of casting conditions, the two resins tend to separate into distinct phases, potentially leading to inferior or inadequate mechanical properties in the final product. Elasticity and Flexibility LDPE is generally more flexible and ductile than PP. The addition of LDPE can therefore increase the flexibility and toughness of the blend, while reducing stiffness. Melting Point Since LDPE has a lower melting point than PP, mixing the two can lead to a decrease in the overall melting point of the blend, depending on the proportions used. Transparency LDPE is typically more opaque than PP. Its addition can therefore reduce the transparency and brilliance of the blend, making it more opaque or milky. Chemical Resistance LDPE and PP are both resistant to many chemicals, but their combination may have a slightly different chemical resistance profile than pure polymers. Transformation The workability of the mix can change with the addition of an LDPE densifier. For example, viscosity during extrusion or injection molding may change, affecting ideal processability conditions What blemishes can be created in the production of LDPE products by using a melting temperature that is too high The use of an excessively high melting temperature when processing LDPE (Low Density Polyethylene) can lead to various blemishes and problems of quality in finished products. We can recall some of the potential problems: - LDPE can degrade when exposed to too high temperatures. This degradation can cause changes in the mechanical properties of the material and produce gases and/or volatile compounds that can form bubbles or voids in the finished product. - Thermal degradation can also lead to discoloration of the polymer. An overheated LDPE can take on a yellowish or brown color. - Thermal degradation can produce compounds with unpleasant odors. This can be particularly problematic for applications where the presence of odor is an important factor, such as in the case of food packaging. - Excessively high temperatures can cause uneven cooling during part formation, leading to incorrect deformations or shrinkage. - The use of too high temperatures can cause the formation of streaks or superficial stains on the product, especially if there are impurities or additives in the material. - Thermal degradation can adversely affect the mechanical, thermal and chemical properties of LDPE. This could result in products with reduced strength, toughness or durability. - At excessively high temperatures, LDPE may become too fluid, making it difficult to form precise details or maintain desired tolerances . Problems with aluminum labels in densified LDPE It often happens that, despite the decantation and centrifuge washing of the LDPE plastic waste, in the densified product there is still the presence of flexible aluminum parts. We must keep in mind the difference between the impurities made up of rigid aluminum fractions and those made up of leaf aluminum. If in the first case the rigidity of the metallic impurity cannot be tolerated, due to a series of negative problems that these can cause to the injection systems, which are the result of poor selection and washing, the presence of aluminum leaf parts do not create technical problems. These parts are made up of packaging labels which can contaminate the films but, being soft, do not cause damage to the systems or final products. There remains an aesthetic aspect that must be considered, but with a view to creating non-aesthetic products, the bright dot which recalls the presence of aluminum foil must be considered “part of the game”. This acceptance of the impurity of aluminum foil can bring significant price advantages on the final product and a considerable availability of raw material on the market. Automatic translation. We apologize for any inaccuracies. Original article in Italian.
SEE MORE
Recycled Plastic Polymers: Drying or Dehumidification?Recycled Plastic Polymers: Drying or Dehumidification?All plastic materials, virgin or recycled, in the form of granules or ground or densified, have a tendency to retain moisture, until they reach a balance with the external environment. This absorption capacity depends, as previously mentioned in another article, on the type of polymer, the air temperature and its humidity.Based on the above considerations, the polymers can be divided into hygroscopic and non-hygroscopic. In fact, in hygroscopic materials, water is absorbed inside the structure by chemically binding with it, while in non-hygroscopic polymers the moisture remains outside the mass, subsequently interfering in the manufacturing process.The plastic polymers, expressed in the forms of granules, ground, densified or powders, are sent for their transformation according to the product to be made and the type of process established.Whether the materials are hygroscopic or non-hygroscopic, the presence of humidity during the melting phase of the polymer mass creates considerable problems as water can become vapor, creating streaks, surface bubbles, irregular thermal shrinkage, structural tensions, deformations or breaks. .Humidity is one of the main causes of imperfections or defects on plastic products made but, at the same time, it is a problem largely neglected or underestimated by operators who mainly use recycled plastics.If we want to list some obvious defects caused by the presence of moisture in polymers, we can mention:• Opaque appearance of the product• Brown streaks• Silver streaks• Weak welding lines• Incomplete pieces• Burrs• Bubbles• Blowholes• Reduction of mechanical properties• Deformations of the element• Degradation of the polymer• Irregular aging• Irregular withdrawalsTo overcome these drawbacks, it is a good idea to dry the material before using it with air jets.In this case we can list two intervention systems, similar to each other, but with different results, which are represented by drying and dehumidification.For drying we can consider a process of insufflation of air sucked into the environment and introduced into a hopper in which the plastic material to be treated is located, for a certain time at a set temperature.This system depends greatly on the weather conditions and the degree of humidity in the air and is recommended only for non-hygroscopic materials.For hygroscopic materials, such as polyolefins, (PP, HDPE, LDPE, PP / PE just to name a few), the forced air drying system seen above is not sufficient, as the intrinsic moisture content in the polymer, makes the process of little effectiveness.In this case it is advisable to dry the polymers through dehumidification, which involves the insufflation inside the hopper, no longer of air in variable environmental conditions, but of air dehumidified through a dryer at a set temperature.The hopper must be insulated to reduce the dispersion of process heat and the material will be in motion, so that during the transit phase inside the hopper it can be hit with jets of hot and dehumidified air.The dryer will produce a constant flow of hot and dry air which will have the ability to significantly reduce the internal humidity of the hygroscopic polymers.Automatic translation. We apologize for any inaccuracies. Original article in Italian.
SEE MORE
Performance of High Sulfone Polymers for Energy StorageEnhancing Proton Exchange Membranes for Future Energy Technologiesby Marco ArezioThe increasing need for efficient and sustainable energy storage technologies has driven research towards innovative materials, including high-sulfonation polymers.These polymers are used to improve the performance of proton exchange membranes (PEM), a crucial component in many energy technologies, such as fuel cells and redox flow batteries.This article will explore recent developments in the use of sulfonated polymers for energy storage, with a focus on their chemical properties, performance, and advancements in thermal and mechanical stability, as well as a detailed explanation of how proton exchange membranes, fuel cells, and redox flow batteries work.Introduction to Proton Exchange Membranes (PEM)Proton exchange membranes (PEM) are key devices for numerous renewable energy applications, particularly in fuel cells and redox flow batteries.PEMs are polymer membranes that selectively allow protons (H⁺ ions) to pass through while blocking other ions and gases.This feature is essential for electrochemical energy conversion and storage, as it enables efficient charge transfer in redox reactions.PEMs are primarily made from sulfonated polymer materials that promote high proton conductivity, which is essential for the proper functioning of advanced energy technologies.Structure and Properties of Sulfonated PolymersHigh-sulfonation polymers are characterized by the presence of sulfonic groups (-SO₃H) along the polymer chain.These groups are responsible for high proton conduction, which is crucial for the efficiency of PEMs. The sulfonation level directly influences the polymer’s proton transport capability, as the sulfonic groups provide the necessary sites for proton migration.However, the presence of a high number of sulfonic groups can compromise the mechanical and thermal stability of the polymer, requiring optimization between conductivity and structural resistance.Structural Modifications to Improve PerformanceTo enhance membrane performance, high-sulfonation polymers are often modified with physical or chemical reinforcements.A common approach is the use of composite materials, where sulfonated polymers are combined with cellulose microcrystals or other nanoparticles to increase mechanical stability without significantly reducing proton conductivity.Other methods involve chemical cross-linking, which improves the material's thermal resistance by reducing water solubility, a major cause of PEM degradation.Electrochemical Performance and Energy StorageThe electrochemical performance of sulfonated polymers largely depends on their ability to maintain high proton conduction levels under varying operational conditions.Polymers with high sulfonation levels exhibit high conductivity but are prone to hydration and thermal stability issues.Recent advancements have introduced new polymers that combine a high density of sulfonic groups with improvements in mechanical resistance, thanks to cross-linkers or reinforcing materials.Proton Exchange Membrane Fuel Cells (PEMFC)Proton exchange membrane fuel cells (PEMFC) are electrochemical devices that convert the chemical energy of a fuel (typically hydrogen) directly into electricity, with water as the only byproduct.In PEMFCs, the proton exchange membrane acts as a solid electrolyte, separating the reactants (hydrogen and oxygen) and facilitating proton transfer from the anode to the cathode.This process is crucial for power generation, as it allows for high conversion efficiency and significantly reduces pollutant emissions compared to traditional power generation methods.Redox Flow Batteries and the Role of Proton Exchange MembranesRedox flow batteries represent another significant application of proton exchange membranes. These batteries store energy in electrolyte solutions containing redox species, which circulate through an electrochemical cell.PEMs act as selective barriers between the two electrolyte reservoirs, allowing proton transfer and preventing solution mixing.This separation is essential to maintain redox reaction efficiency and ensure a long battery life. Redox flow batteries are particularly attractive for storing energy from intermittent renewable sources like solar and wind, offering great flexibility and scalability.Challenges and Future Prospects in Polymer Development for Energy StorageDespite progress, significant challenges remain for the widespread use of sulfonated polymers in energy applications.The primary challenge lies in balancing proton conductivity with mechanical and chemical stability. Future studies may focus on new cross-linking approaches or synthesizing polymers with a more optimal distribution of sulfonic groups along the polymer chain.Additionally, the development of composite materials and the use of nanomaterials represent promising research directions to improve PEM performance without compromising their stability.ConclusionsHigh-sulfonation polymers present a promising solution for energy storage due to their high proton conductivity and applications in advanced electrochemical technologies such as fuel cells and redox flow batteries.Research is constantly evolving to overcome current limitations, and recent advancements in polymer structural modification and composite development indicate a promising path toward large-scale adoption of these technologies.© All Rights Reserved
SEE MORE
What is Epoxy Resin and how is it recycledA polymeric compound of extreme importance for the most disparate uses for which it is intended, but with a complicated relationship with recycling An epoxy resin is a type of thermosetting polymer that, when mixed with a hardener, undergoes a chemical reaction called "cross-linking." This process transforms the resin from a liquid or viscous state to a solid, rigid state. The main characteristics and aspects of epoxy resins: Molecular Structure Epoxy resins contain epoxy groups (an oxygen atom bonded to two adjacent carbon atoms in a chain) that are reactive and allow cross-linking with various hardeners. Hardeners For an epoxy resin to harden, it must be mixed with a hardener (or curing agent). This hardener reacts with the epoxy groups of the resin, forming a solid three-dimensional structure. Property Once cross-linked, epoxy resins have excellent mechanical properties, chemical resistance and adhesion. They are also electrically insulating. Applications Due to their excellent properties, epoxy resins are used in a wide range of applications, such as adhesives, coatings, fiber-reinforced composites, printed circuit boards and much more. Handling Epoxy resins can be modified to have specific properties. For example, they can be formulated to have fast or slow setting times, or to withstand extreme temperatures. Aesthetics There are clear epoxy resins that are used in artistic and decorative applications, such as table coverings or jewelry making. It is important to note that once an epoxy resin is fully cross-linked, it becomes thermoset. This means that, unlike thermoplastic polymers, it cannot be remelted or shaped by the application of heat. Recycled epoxy resins Research on recyclable epoxy resins has been at the center of great interest in recent years. These types of polymers, as we said, are thermosets, meaning that once cross-linked or hardened, they cannot be easily recycled or reprocessed. However, there are studies aimed at developing "recyclable" or "reproducible" epoxy resins that can then be depolymerized or returned to a liquid state after the cross-linking process. Some of these recyclable epoxy resins have been designed to depolymerize through specific stimuli, such as heat or exposure to certain chemicals. The idea behind these materials is that, once depolymerized, they can be recycled. Research on recycled episodic resins Epoxy resins are widely used in a variety of industrial applications due to their excellent mechanical adhesion and chemical resistance properties. However, one of the main challenges associated with these resins is the difficulty in their recycling due to their thermosetting nature. Several recycling solutions have been proposed to solve the problem: Chemical depolymerization This process involves the use of chemicals to break cross-links in the epoxy mesh. Once depolymerized, the resins can potentially be reprocessed. Dynamic cross-linking Some epoxy resins have been modified to have dynamic cross-links that can exchange under certain conditions. This means that they can be cross-linked (hardened) and then "de-cross-linked" when exposed to certain stimuli such as heat or light. Mechanical recycling Instead of trying to depolymerize the resin, this approach focuses on shredding or crushing the cured epoxy material into particles, which can then be reused as fillers or reinforcements in new composites. Recovery of fillers and reinforcements In many epoxy composites, the epoxy matrix is only one component. Other components, such as carbon fibers or glass, can be recovered from the composite and reused. Research in this field is constantly evolving. While some of these techniques are still under development and may not be commercially ready or economically feasible on a large scale, they nevertheless represent important steps forward towards greater sustainability in the field of epoxy materials. History of epoxy resins Epoxy resins are polymers that have become fundamental in many industries due to their exceptional mechanical, adhesion and chemical resistance properties. Here is a brief history of epoxy resins: Early years (1930-1940) Epoxy resins were first developed in the 1930s. Swiss chemist Paul Schlack is often credited with making the first epoxy resin while working for the German company IG Farben. Shortly thereafter, in the United States, the Devoe & Raynolds Company began developing epoxy resins based on bisphenol A and epoxychlorohydrin. Second World War During World War II, there was a growing need for high-performance materials, and epoxy resins began to be used in military applications. 50s and 60s After the war, the production and use of epoxy resins expanded dramatically. New types of resins and hardeners were developed, leading to a wide range of properties and applications. During this period, epoxy resins became popular as structural adhesives and as matrices for fiber-reinforced composites. 70's Growing environmental awareness led to the search for solvent-free, low-volatile organic compound (VOC) epoxy systems. During this period, epoxy resins also became essential in the production of printed circuit boards. 80s and 90s The aerospace industry has begun to significantly use epoxy resins for lightweight, high-performance composites. Research also focused on improving thermal properties and reducing internal stresses during crosslinking. 2000 – Today With the growing need for sustainable materials, there has been an interest in researching recyclable or biodegradable epoxy resins. The miniaturization trend in electronics has also led to epoxy resins with specific properties for applications such as semiconductor encapsulation. Today, epoxy resins are ubiquitous in many industries, from construction and marine, to electronics, aerospace, and beyond. Continuous innovations and research in this field continue to expand the potential and applications of these versatile materials. Where epoxy term papers are used Epoxy resins are used in a wide range of applications. Here are some of the main applications of epoxy resins: Stickers These polymers are remarkably adhesive and are used as structural glues for many industrial applications. They can adhere to a wide range of materials, including metals, plastics, wood and ceramics. Coatings Epoxy resins are used to coat industrial and commercial floors, offering abrasion resistance, chemical resistance and easy cleaning. Composites These polymers are often used as a matrix in fiber-reinforced composites, such as those with carbon fibers or glass fiber. These applications are common in industries such as aerospace, automotive and sports. Printed circuits Epoxy resins are a fundamental component in the production of printed circuits used in electronics. Protection Epoxy resins are used to protect sensitive electronic components, isolating them from the external environment. Marine structures Due to their chemical resistance, epoxy resins are used to repair and protect marine structures, such as boat hulls. Repairs Because of their strong adhesion and structural properties, epoxy resins are often used to repair a variety of objects, including those made of metal, ceramic, and wood. Dental activities Some types of epoxy resins are used in dentistry for fillings and adhesives. Art and craftsmanship Clear epoxy resins have become popular in arts and crafts, used to create jewelry, furniture, artwork and other artistic objects. Concrete structures Epoxy resins are used for repairing, strengthening and protecting concrete structures. Automatic translation. We apologize for any inaccuracies. Original article in Italian.
SEE MORE
Lightweighting in Plastic Packaging: Innovative Design and Material Strategies for Optimal PerformanceExplore advanced lightweighting techniques for plastic packaging, balancing material reduction, structural strength, and environmental sustainability by Marco Arezio The plastic packaging industry faces a dual challenge: meeting the growing demand for environmental sustainability while maintaining or improving the functional performance of products. In this context, "lightweighting," or reducing the weight and material used in packaging , emerges as a key strategy. It's not simply a matter of using less plastic, but a complex engineering approach that aims to optimize design and material selection to ensure packaging remains robust, safe, and efficient throughout the entire value chain, from production to final consumption. This technical article explores the design methodologies and material innovations that achieve a critical balance between reducing weight and maintaining performance. Fundamental Principles of Lightweighting Lightweighting is not a linear process, but a multifactorial optimization that requires a deep understanding of material properties and the mechanical stresses to which the packaging will be subjected. The key principles include: Life Cycle Assessment (LCA): Evaluate the overall environmental impact of weight reduction, considering not only the reduced material consumption, but also the implications for logistics (less weight = less fuel consumption in transport) and recyclability. Structural Optimization: Redesigning the packaging geometry to maximize strength with minimal material. This includes introducing ribs, curvatures, reinforcements, and optimizing wall thickness only where strictly necessary. Advanced Materials Selection: Identify polymers with superior mechanical properties (e.g., increased stiffness, impact resistance) that allow for reduced thickness without compromising integrity. Innovative Manufacturing Processes: Adopt molding and forming technologies that allow for more uniform material distribution and the creation of complex geometries with precision. Design Techniques for Weight Reduction Design plays a key role in lightweighting. The most effective techniques include: Topological Optimization: Using advanced software to identify the optimal material distribution within a given geometry, eliminating areas not essential for structural strength. This leads to organic and often counterintuitive, yet extremely efficient, shapes. Thin-Wall Design: Systematically reducing the thickness of the container walls. This technique requires materials with high stiffness and flexural strength, and high-precision injection molding or blow molding processes to avoid defects such as warping or brittleness. Sandwich and Multilayer Structures: Creating walls composed of different layers, where a lightweight core layer (e.g., polymer foam or recycled material) is sandwiched between two denser, more resistant outer layers. This configuration offers excellent rigidity with low weight. Reinforced Geometry: Incorporation of ribs, grooves, domes, or other structural features that increase compressive and flexural strength without adding significant mass. For example, the design of PET bottles for carbonated beverages leverages internal pressure to contribute to structural rigidity. Feature Integration: Redesigning packaging to reduce the number of components. For example, an integrated cap or closure system that is part of the container's main structure can eliminate the need for additional parts and their weight. Innovative Materials for Lightweighting Innovation in polymer materials is critical to the success of lightweighting: High-Performance Polymers: Materials such as PET (Polyethylene Terephthalate) with higher intrinsic viscosity or polypropylene (PP) and polyethylene (PE) with optimized molecular weight distribution, offer superior mechanical properties that allow for reduced thicknesses. Fiber-Reinforced Polymers: Adding glass, carbon, or natural fibers (e.g., cellulose) to polymers can significantly increase stiffness, tensile strength, and impact strength, allowing for further lightweighting. Polymer Nanocomposites: The incorporation of nanoparticles (e.g., clays, graphene, carbon nanotubes) into the base polymer can dramatically improve barrier (against gas and moisture) and mechanical properties, making the production of ultra-thin films and containers possible. Bio-Based and Recycled Polymers: The use of bioplastics (e.g., PLA, PHA) or recycled polymers (rPET, rHDPE) is crucial for sustainability. The challenge is maintaining desirable mechanical properties, which are often compromised by recycling cycles or the intrinsic properties of bio-based materials, requiring specific additives or blends. Foamed Materials: The introduction of gas during the molding process creates a cellular structure within the polymer, significantly reducing density and weight while maintaining good stiffness. Structural foams are particularly promising for applications where compressive strength is critical. Balancing Material Reduction and Strength: The Challenges The trade-off between reducing material and maintaining performance is the central challenge of lightweighting. Excessive reduction can lead to: - Impairment of Functionality: The packaging may not adequately protect the product from external shocks, vibrations or pressures. - Line Problems: Containers that are too light or flexible can cause problems in high-speed filling and packaging lines. - Loss of Value Perception: Excessively light packaging may be perceived by the consumer as less robust or of lower quality. - Reduced Shelf Life: For food products, thinner packaging could compromise barrier properties, reducing shelf life. To mitigate these challenges, a holistic approach integrating Finite Element Method (FEM) simulations to predict structural behavior, rigorous laboratory testing of mechanical and barrier properties, and field trials to evaluate packaging performance under real-world transportation and storage conditions is essential. Conclusions Lightweighting plastic packaging is not just a trend, but a strategic necessity for modern industry. By applying advanced design techniques such as topology optimization and thin-wall design, combined with the use of innovative materials such as high-performance polymers, nanocomposites, and foamed materials, significant weight reductions can be achieved without compromising functionality. The key to success lies in an integrated engineering approach that carefully balances the needs of material reduction with those of strength, durability, and sustainability, guiding the industry toward a more efficient and responsible future. © Reproduction Prohibited
SEE MORE
The evolution of Polymeric Reinforcement FibersStarting from 1937 with the invention of glass fiber, new and daring polymeric solutions of considerable technical-commercial interest have been developed The evolution of plastics in the period following the end of the Second World War has led the sector to continuous scientific innovation in competition with itself. The discovery of new polymeric bonds and new commercial applications has revolutionized the industrial field by giving birth to new products, replacing others made of traditional materials and improving the quality ratio price of the artifacts. In addition to discovering new polymers, technical solutions were discovered that led to an enhancement of the performance of the base polymer, managing to create new fields of application until then unknown. In fact, the resistance capacity achieved through polymers and polymer-matrix composites was, until a few years ago, unthinkable. In particular, the HP Fibers sector, designed to provide performances that traditional textile fibers were not able to achieve, especially as regards mechanical capabilities , thermal and chemical, have created a real technological revolution. Materials which, in addition to being able to meet particular requirements, must show a good aptitude to be included in textile cycles, even if modified. Born about 30 years ago on the thrust of some strategic sectors - especially military and aeronautics, they are now exploited in the most diverse fields, from the environmental to the clothing sector protective: • geotextiles for soil containment able to withstand very strong pressures • fabrics for ballistic protection capable of absorbing the energy of the bullets • yarns for protective clothing resistant to the energy generated by lightning • textile reinforcements to be used in composite materials for structural use in the building field. The first fiber with high performance both tensile and thermal was the glass fiber (1937) produced by Owens and Corning Glass, consisting mainly of silica, oxide of calcium, aluminum oxide, boron oxide. Belonging to the family of inorganic fibers, it had an annual growth of 15-25% until the 60s - 70s, when the fibers appeared on the market carbon and aramidic fibers, even if to date glass fiber holds the first place in terms of volumes used as a reinforcing fiber. Carbon fibers, discovered in 1879 by Edison, have only been commercialized since 1960, according to a process developed by William Watt for Royal Aircraft in the UK . But the real revolution in the world of high-performance fibers began with the appearance on the market (1965) of the aramid fibers developed by DuPont, initially as meta-aramids (Nomex), fibers with a very high melting and decomposition temperature (600 ° - 800 ° C) and excellent electrical insulation characteristics. These properties make them particularly suitable for the production of fabrics or felts with which to make protective clothing (most of the Formula 1 driver suits are made of Nomex , precisely because of its fireproof properties, as well as those of oil platform operators) and for the filtration of hot gases. In the form of paper or cardboard, they are used for electrical insulation and, in a honeycomb shape, for the production of composite materials. A few years later (1972) again DuPont introduced pararamidic fibers (Kevlar) on the market, thus opening the new era of yarns with high tension and thermal performance: • excellent mechanical resistance • stiffness • high radiation absorption • impact resistance • to heat • to the flame. With Kevlar fiber-reinforced composites, five times stronger than steel for the same weight, the airbags were created that allowed the probes on Mars and the parachute of the Galileo probe, sent to Jupiter. A cover made with Kevlar-reinforced composites covers the walls of the International Space Station, in orbit around the earth, to protect them from damage caused by micrometeorites. Kevlar fiber - marketed in the form of filament, staple and pulp, replaces asbestos in the lining of clutches and brakes in all cars coming from the lines European production. Alongside aramid fibers, aromatic polyester fibers have appeared on the market, those produced with aromatic heterocyclic polymers, or made with the use of flexible molecules (such as high molecular weight polyethylene), for the production of fibers with high molecular orientation along their axis, using a new spinning process, called gel spinning. In the production of industrial products where resistance must be combined with lightness and flexibility, HP textile fibers are a valid solution, the one that still holds back a their most extensive use is the high cost, mainly a consequence of some technical problems related to their workability. Generally the higher the performance of the material, the higher the difficulties associated with its transformation. This is more evident for fibers with very high mechanical resistance, in fact to give them this performance the production method normally followed is to submit the material, after the supply chain, with very high ironing. With this technique the desired high tenacity is obtained but at the expense of the elongation, consequently the fibers have a low deformability and are rigid, this involves spinning difficulties . Conversely, an exceptional increase in elongation, therefore in elasticity, is obtained at the expense of toughness and moisture absorption capacity, as well as a high resistance to chemical agents makes the absorption of moisture almost zero and creates difficulties in dyeing the fibers.Automatic translation. We apologize for any inaccuracies. Original article in Italian. Info Cecilia Cecchini
SEE MORE
How to weld recycled plastic materials.Updated Technical Guide to the Welding of Plastic Components by Hot Plate, Hot Gas, Extrusion, Ultrasound, Radio Frequency, Laser, Infrared, Vibration, Spin and Electrofusion, with a Focus on Standards, Process Parameters, Laboratory Testing and the Critical Issues of Recycled PolymersAuthor: Marco Arezio. Expert in circular economy, polymer recycling and industrial processing of plastics. Founder of the rMIX platform, dedicated to the enhancement of recycled materials and the development of sustainable supply chains.Original date: April 20, 2020Updated on: March 26, 2026Reading time: 13 minutesWhat plastic welding is and why it now requires more control than in the pastIn 2020, the welding of plastic products could still be described as a simple joining of two surfaces brought to temperature and compressed together. In 2026, that definition is still true, but it is too poor to explain what really happens in workshops, on automated lines and on construction sites. Today, thermoplastic welding is a process technology governed by materials, joint geometry, thermal parameters, pressure control, contact times, cooling, personnel qualification and digital traceability systems. ISO 21307 remains the reference standard for butt welding of PE systems and has been confirmed as the current version; the qualification of thermoplastic welders remains based on EN 13067; and the world of electrofusion continues to evolve in terms of equipment and joint data coding.To say “welding plastic” therefore means obtaining, through molecular diffusion or localized melting of the interface, a permanent bond capable of transferring mechanical stresses, ensuring fluid tightness, or meeting much more sophisticated functional requirements: insulation, biocompatibility, dimensional stability, clean joint appearance, absence of particulates, compatibility with automation and in-line controls. Not by chance, TWI includes among the main industrial techniques hot plate, hot gas, extrusion, ultrasonic, high frequency, friction welding, vibration, spin and laser, and identifies among the current challenges the digitalization of processes and the development of defect acceptance criteria.Which polymers can be welded and which materials remain criticalThe basic rule has not changed: the materials best suited to welding are thermoplastics and, in many cases, thermoplastic elastomers. Thermosets and cross-linked elastomers cannot be remelted reversibly and therefore are not suitable for hot welding in the way that PE, PP, PVC, ABS, PA, PC, PMMA or PET are under specific conditions. TWI in fact recalls that welding techniques can be applied to thermoplastics and thermoplastic elastomers, whereas chemically cross-linked materials cannot be heated and reshaped without degrading.The welding of dissimilar materials, often trivialized in popular texts, must also be handled with caution. In general, dissimilar polymers do not weld well; however, compatible combinations do exist, especially among amorphous materials with similar glass transition temperatures, such as PMMA/ABS, PS/ABS or PMMA/PC in specific applications. Chemical and thermal compatibility remains decisive: if the materials melt or soften over intervals that are too far apart, or if their molecular affinity is insufficient, the joint is weak, brittle or unstable over time.For this reason, the first real technical question is not “which machine should I use to weld?”, but “which resin am I joining, in what surface condition, with what moisture content, with which additives, with which geometry and with what previous life of the material?” In the case of recycled polymers, this question becomes even more important, because mechanical recycling introduces rheological variability, additive residues, possible contamination and degradation phenomena that narrow the useful welding window. Recent studies on HDPE show that chain scission dominates in the initial stage of degradation, whereas exposure to oxygen can shift behavior toward long-chain branching phenomena; in addition, technical reports on recyclate quality indicate that additives and contaminants can compromise the performance of regenerated material. It is therefore reasonable to conclude that, in recyclates, weldability depends even more than in virgin material on the prior control of MFR, contamination, stabilization and lot uniformity.Hot plate welding: the most solid industrial method for parts and pipesHot plate welding, also known as mirror welding or heated tool welding, remains one of the most robust and versatile technologies for joining molded components and pipes. The principle is only apparently simple: a heated metal plate melts the surfaces to be joined; then the plate retracts; finally, the parts are pressed against each other and held under load until cooling. But joint quality depends on a precise sequence: initial bead-up, heat soak, minimal transfer time and controlled cooling. TWI indicates that the key parameters are time or height of the initial bead, heat soak time, dwell time, cooling time, heating/cooling pressure and plate temperature, normally set about 60-100 °C above the melting temperature of the material.From the equipment side, a hot plate machine normally includes the heating plate, movement carriages, part clamping systems and machine control, now almost always microprocessor-based. Plates may be flat or contoured, often made of aluminum or aluminum bronze, and are in many cases coated with PTFE-based non-stick surfaces to prevent adhesion of the melt. This is an important detail: it is not enough to have heat; uniform heat transfer, stable geometry and clean separation without tearing the melt are required.It is the ideal method when strength, repeatability and leak tightness are required, for example on tanks, hollow bodies, automotive assemblies, pipes and fittings. Its limitation is not so much joint quality as cycle time and flash management, since expelled material often remains visible if the joint is not designed with traps for the displaced melt. For this reason, the design of the weld edge is an integral part of the technology and not a secondary detail.Hot gas and extrusion welding: equipment and filler materials for workshop and field workHot gas welding is still one of the most widespread techniques in plastic fabrication, sheet processing, the construction of tanks, chemical plants, linings, membranes and repairs. The process uses a stream of hot gas, usually air, to simultaneously heat the base material and the filler rod. According to TWI, the typical jet temperatures are in the range of about 200-400 °C, and the welding rod must be made of the same polymer as the components being joined. This point must be strongly emphasized: filler material is not a generic accessory, but a structural part of the joint.The equipment consists of hot air guns with integrated blower, heating element, thermostat and interchangeable nozzles, together with welding rods or sticks, rollers, scrapers, bevel-preparation tools and, in more advanced systems, automatic feed devices. Welding speed, nozzle shape, preheating of the material and the pressure applied by the welder or by the nozzle itself make the difference between a full bead and a joint with internal voids.When thickness increases, the more suitable technology becomes extrusion welding. Leister indicates that extrusion is preferable for thicknesses around 6 mm and above, and that it allows shorter times, greater mechanical strength and lower residual stresses than manual hot gas welding. The principle is as follows: the surfaces are first brought to a thermoplastic state with hot air, then a portable extruder deposits plasticized material through a welding shoe shaped to the geometry of the joint. Here too, the filler material must be compatible and of the same type as the base material.In real work, the most common defects arise from errors that are often underestimated: excessive temperature, residual moisture in the welding rod, excessively humid ambient air, a cold shoe, poor surface preparation or low polymer quality. Leister explicitly points to these factors as causes of cavities, voids and poor weld bead quality. For those working on recycled components or on lots of material that are not perfectly homogeneous, this observation is even more important.Ultrasonic welding: speed, precision and tightness on technical componentsUltrasonic welding is the most representative technology of high-productivity engineering plastics. Ultrasonic waves, in a range that Herrmann places between 20 and 70 kHz, are transformed into mechanical vibrations and transmitted by the sonotrode into the contact area; friction and local dissipation produce the heat necessary to melt the interface, which then consolidates under pressure. Emerson describes the process as rapid, efficient and capable of achieving strong, clean and even hermetic seals, with applications in packaging, medical devices and electronics.The machine consists of a generator, converter, booster, sonotrode and pressure/positioning system. Herrmann emphasizes that the geometry of the joint must be designed according to the material and the welding requirements; in other words, ultrasonic welding does not forgive design approximations. This is why it is used on small or medium-sized parts where extremely short cycle times, automation, joint cleanliness and the absence of consumables such as adhesives or solvents are required.Compared with 2020, the quality leap lies in the digitalization of process control and integration with automated cells. Emerson in fact presents digital and automatable ultrasonic systems to ensure repeatability, fine energy control and consistent quality. The environmental advantage is twofold: chemical consumables are reduced and, in many applications, packaging systems can also be made lighter.Laser and infrared welding: clean technologies for aesthetic and automated jointsLaser welding of thermoplastics has, over the years, corrected much of the imprecise terminology used in the past. It is not simply a matter of “hitting the surface” with a beam: in the most common configuration, the beam passes through a transparent or transmissive component and generates heat at the interface on a second absorbent component, often compounded with carbon black or specific absorbers. TWI highlights that the process allows unmelted external surfaces, very clean welds, high automation and excellent joint aesthetics, but requires good fit-up of the edges, clean surfaces and at least one component capable of transmitting a sufficient portion of the radiation.Infrared welding is an advanced derivative of the hot plate principle, but in a non-contact configuration. TWI distinguishes between non-contact hot plate and IR lamp systems: in the first case, a hot plate, also brought to between 310 and 510 °C depending on the polymer and the machine, remains at a very short distance from the part without touching it; in the second, banks of infrared emitters rapidly heat even large areas. The main advantage is the absence of contact with the heat source, which reduces contamination, sticking and surface marks. Emerson presents infrared as a process capable of producing particulate-free joints with high mechanical load capacity, useful for sensors, electronic housings and medical products.In 2026 these two technologies are increasingly attractive where aesthetics, automation, joint cleanliness and very fine control of input energy are required. They are not, however, universally superior: they cost more, require more accurate joint design and, in the case of laser, optical and fit-up conditions that other processes tolerate more easily.Vibration, spin and radio frequency welding: when specialized processes are neededVibration welding is a form of linear friction welding. Emerson describes it as an energy-efficient technology, ideal for large parts, complex areas, multi-plane surfaces or irregular curves, with strong applications in automotive and household appliances. The recent “Clean Vibration Technology” evolution was developed precisely to reduce flash and particulates, two typical limitations of linear friction processes.Spin welding, on the other hand, is rotational friction welding, suitable for circular joints. TWI explains that one of the two components rotates against the other under pressure, generating frictional heat until the interface melts. It is an excellent solution for fittings, caps, cylindrical connections and hollow components when the geometry lends itself to rotational movement.Radio frequency or high frequency, finally, is the typical technology for polar materials. TWI recalls that the process is based on the orientation and vibration of charged molecules along the polymer chain and is therefore particularly suitable for PVC and polyurethanes; other materials such as nylon, PET, EVA and some ABS can be welded only under particular conditions, whereas PE and PP are generally unsuitable. The Italian manufacturer GEAF confirms that the most reactive materials include PVC, EVA, PU, TPU and some PET families, and identifies the permitted industrial frequencies as 13.56 MHz, 27.12 MHz and 40.68 MHz.Here it is worth correcting a frequent misunderstanding: high frequency is not a “universal” technology for plastics, but a highly selective one at the molecular level. It works very well on polarizable films and flexible products, much less well — or not at all — on conventional polyolefins.Electrofusion and welding of PE systems: standards, control and traceabilityWhen entering the world of polyethylene piping for gas, water and fluid distribution, welding takes on an even more rigorous normative dimension. ISO 21307 defines butt welding procedures for PE systems and specifies three reference procedures; ISO 12176-2:2025 instead governs the performance requirements of control units for electrofusion; ISO 12176-4 and ISO 12176-5 regulate the systems for coding and traceability of joining operations.This means that today welding does not end with cooling of the joint. It must leave a documentary trace: machine data, operator, component code, assembly method, welding result. ISO 12176-4 specifically provides for the coding of component, method and operation data for PE systems, while equipment and software manufacturers are moving toward digital reports and cloud-stored recipes. Leister, for example, offers systems for digital documentation of welding parameters in real time; the same trend is followed by the traceability systems of electrofusion control units.The real difference compared with the old way of looking at plastic welding lies here: the joint is no longer simply “well made,” but verifiable, traceable and reproducible. And this is what the market now requires in critical sectors.Laboratory testing, inspections and typical defects of plastic weldsA welded joint is not judged by appearance alone. Checks may be destructive or non-destructive and depend on the product, the material and the application risk. TWI explicitly indicates that testing of plastic welds includes mechanical tests, non-destructive tests and, in the case of pipes, dedicated equipment for the whole-pipe tensile rupture test.For PE butt joints, ISO 13953 describes the method for determining tensile strength and failure mode of specimens taken from the joint; for electrofusion, the historical ISO 13954:1997 has been withdrawn and replaced by ISO 13954:2025, which specifies a method for evaluating the ductility of the joint interface in PE electrofusion sockets. These references clearly show how the sector has shifted from purely empirical evaluation to structured validation of joint behavior.On a practical level, the most common defects remain the same, even if the machines change: insufficient surface preparation, misalignment, excessively long dwell time, inadequate pressure, excessive or insufficient temperature, surface contamination, moisture, incompatible filler rod, forced cooling or premature movement of the part. Recycled materials add irregular viscosity, additive residues and lot thermal instability. The result may be a joint that appears acceptable but is fragile, porous or unable to guarantee long-term tightness.How to choose the best welding system for virgin or recycled plastic articlesThe process is not chosen starting from the machine, but from the application. If I have to join PE/PP pipes or hollow bodies with high mechanical performance and tightness, hot plate or electrofusion are the most solid candidates. If I work on sheets, tanks and plastic fabrication, hot gas and extrusion remain the dominant technologies. If I need speed, automation and precision on small technical components, ultrasonics are often the best answer. If I seek aesthetics, a clean joint and high-level automation, laser and infrared can offer decisive advantages. If I have large or complex parts, vibration is often more realistic. If the joint is circular, spin welding remains a very efficient solution. If I handle films or flexible products in polar materials, radio frequency is still a very strong industrial standard.For recycled materials, however, one more criterion is needed: it is not enough to know “what polymer it is.” You need to know how stable it is. A recycled PP or PE with MFR out of control, moisture or contaminant presence, or already advanced oxidation may weld poorly even with excellent equipment. This is why in 2026 plastic welding is increasingly intertwined with material characterization, rheological analysis, lot traceability and process documentation. This is the real evolution compared with the 2020 text: welding is no longer just a thermal operation, but an integrated system linking material, machine, data and quality.ConclusionsJoining two plastic articles does not simply mean “melting and pressing.” It means choosing the correct process according to the nature of the polymer, the geometry of the joint, the level of tightness required, the service environment, the possibility of automation and the actual quality of the material, especially when it is recycled. Plastic welding in 2026 is more specialized, more documented and more demanding than it was in 2020. But precisely for this reason it is also more reliable: standards are clearer, equipment is smarter, controls are stricter and joint quality is less and less left to the intuition of the individual operator.FAQ – Plastic WeldingWhich plastics weld best?In general, thermoplastics: PE, PP, PVC, ABS, PC, PMMA, PA and some PET or TPE, provided the process is compatible with the thermal behavior of the polymer. Thermosets and cross-linked elastomers are not suitable for conventional hot welding.Can different plastics be welded together?Only in limited cases. Some combinations of amorphous polymers with similar thermal behavior may work, but the general rule remains that dissimilar materials are difficult to weld with structural success.What is the best system for thick parts or sheets?For high thicknesses and plastic fabrication, extrusion welding is often preferable to manual hot gas welding, because it ensures greater productivity, better strength and lower residual stresses.When is it worth using ultrasonics?When extremely rapid cycles, automation, joint precision and the absence of adhesives or consumables are required, especially in packaging, medical, electronics and technical components.Does radio frequency work on PE and PP?Generally no. RF is mainly suitable for polar materials such as PVC and PU/TPU. Nylon, PET, EVA and some ABS require particular conditions; PE and PP are not normally suitable.Can recycled materials be welded well?Yes, but with greater caution. Success depends on rheological stability, degradation undergone during reprocessing, the presence of contaminants, moisture and lot consistency. This is why material controls are decisive.Technical and regulatory sourcesThe update and in-depth information contained in this article derives from technical and regulatory reference documentation, including ISO 21307, ISO 12176-2:2025, ISO 12176-4, ISO 12176-5, ISO 13953, ISO 13954:2025, UNI EN 13067:2021, TWI – The Welding Institute, Emerson/Branson, Herrmann Ultraschall, Leister and GEAF.Category: news – technical – plastic – recycling – weldingImage under license© Reproduction Prohibited
SEE MORE
Thermosetting Processing: Molding Compounds, Process Technologies, and Innovations 2025Technical guide to processing thermosetting materials: molding compounds, compression and injection molding, curing times, and Industry 4.0 innovations March 2026 | Category: Plastics Processing Technologies Author: Marco Arezio Thermoset materials occupy a strategic position in the plastics industry due to their ability to form irreversible three-dimensional cross-linked structures during the curing process. Unlike thermoplastics, they cannot be remelted once cured. This characteristic, which might seem limiting at first glance, translates into superior mechanical, thermal, and electrical performance in applications where conventional polymers simply cannot compete. This technical article takes an in-depth look at the thermosetting plastics manufacturing process, from molding compound preparation to the latest innovations related to Industry 4.0, digital twins, and artificial intelligence applied to process control. Market Data: The global thermoset injection molding market is expected to grow steadily, driven by demand from the automotive, electronics, and construction industries—sectors that require superior thermal resistance, dimensional stability, and electrical insulation. 1. What is a thermosetting material and why is its processing different? Thermosets are chemically cross-linked polymers: during the forming process, they undergo a polymerization reaction that creates covalent bonds between the macromolecular chains, generating a stable and infusible three-dimensional network structure. This reaction is irreversible: subsequent heat cannot melt the material, but can only degrade it. The practical implications for processing technology are significant. Raw materials must be largely in their final form before entering the mold. Machinery must be designed to prevent premature activation of the reaction in the plasticizing cylinder by maintaining the mass at a controlled temperature below the gelation threshold, and to instead provide the mold contents with sufficient heat for complete hardening. Classification of raw materials: Based on the processing technology, thermosetting semi-finished products are divided into: (a) thermosetting molding compounds, flowable masses worked under heat with rapid hardening; (b) casting resins, typically liquid or made liquid by moderate heating, with hardening at room temperature or by accelerators; (c) polyurethane systems, which require a dedicated technology for mixing and dosing the reactive components immediately before forming. 2. Thermosetting molding compounds: composition and preparation 2.1 Composition of the moulding masses Thermoset molding compounds are composite systems consisting of resin as a binder and fillers that provide the desired mechanical, thermal, and aesthetic properties. The resin—usually phenolic, aminoplastic, epoxy, or unsaturated polyester—is combined with powdered or fibrous fillers such as mineral flour, wood flour, short glass fibers, paper, fabrics, fiber skeins, or reinforced fabric scraps. The choice of filler largely determines the application profile of the final compound. Mineral fillers improve thermal resistance and stiffness; glass fibers increase mechanical strength and toughness; organic fibers (cellulose, jute) lower density and cost. In modern compounds, such as Bulk Molding Compounds (BMC) and Sheet Molding Compounds (SMC), short or long glass fibers are distributed to optimize isotropy and strength. 2.2 The preparation process The preparation of molding compounds with powder-like fillers or short fibers involves premixing in the dry state, followed by plasticization and homogenization in roller mixers or twin-screw extruders. Simultaneously, the resin is prepolymerized or precondensed to bring it to the viscosity suitable for producing flowable compounds (state B or C). The lamination rolls or extruded chips are subsequently ground and fractionated to a uniform particle size. For masses with coarse fibers or offcuts, production occurs primarily in paddle mixers through impregnation with soluble liquid resins, followed by controlled drying. Masses reinforced with long continuous fibers are instead produced by impregnating hanks and then shredding the strips. The layers are resin-coated in specialized impregnation machines. Technical note: The quality of the mixing and the control of the pre-polymerization state of the resin are critical factors that directly influence the flowability in the mold, the curing time and the mechanical properties of the final product. 3. Injection molding of thermosets: parameters and critical issues 3.1 The injection molding cycle In thermoset injection molding, the production cycle is governed by two fundamental, mutually influencing variables: the dwell time in the cylinder and the curing time in the mold. The cycle time is primarily determined by the latter, since—unlike thermoplastics, where cooling dominates—in the case of thermosets, the chemical crosslinking kinetics dictate the timing. The molding mass is loaded into a cylinder kept at a controlled temperature (generally below 120°C), where it must remain flowable for 3–6 minutes without initiating cross-linking. Once injected into the heated mold, the high temperature of the mold rapidly activates the reaction: the product hardens, is extracted while still hot, and the cycle begins again. 3.2 The dependence of the curing time on the wall thickness The most critical design parameter is the maximum wall thickness. As shown in the technical literature (Fig. 4.99 of the reference text), for injection molding of thermoset phenoplastics, the cycle time remains substantially independent of the thickness up to about 10 mm, thanks to the fact that the control variables are governed by the curing time and not by the cooling time. For compression molding without preheating, however, the dependence is markedly linear: for 20 mm walls, cycle times of up to 6–8 minutes are required. High frequency (HF) or microwave dielectric preheating and screw pre-plasticization represent the most effective techniques for reducing cycle times in compression molding, allowing even thick walls to approach injection molding performance. 4. Compression molding: the fundamental process 4.1 Operating principle The compression mold consists of a heated lower and upper part, mounted on a hydraulic press. The molding mass is fed into the open mold using piston dispensers, volumetric fillers, or automatic scales. After the mold is closed, the mass, heated to flow temperature, fills the cavity under pressure, hardens, and is ejected while still hot. The compression pressure varies depending on the state of the mass: approximately 50 bar for wet, non-preheated masses, up to 150 bar for preheated masses, with peaks of up to 400 bar for special applications. For phenolic and aminoplastic resins, which develop volatile components during curing, it is advisable to vent the mold by briefly lifting the punch to avoid the formation of internal porosity. 4.2 Rotating carousel machines Automatic compression molding machines almost universally adopt rotating carousel configurations, with up to 20 molds mounted on a rotating carriage. The molds rotate cyclically between the feeding station, the closing and curing station, and the ejection and cleaning station. This architecture allows for the long curing time to be exploited by distributing it across multiple stations in parallel, achieving high overall productivity despite long unit cycles. 4.3 Powder coating in the mold An increasingly popular finishing technology for compression molding parts is in-mold powder coating. A fine-grained powder coating (100–200 µm) is electrostatically deposited onto the open, hot mold. During the subsequent compression molding process, the powder forms a porous, friction-resistant, and pre-colored integral layer with the resin, eliminating post-painting operations and reducing waste. 5. Management of volatile substances and product quality One of the most critical aspects in the processing of thermosets — particularly for compression and transfer molding — is the control of volatile substances (condensation water, residual solvents, ammonia in aminoplastic systems) that develop during the crosslinking reaction. For compression molding, aeration of the mold is essential: this is done by slightly opening the die for 2–3 seconds immediately before applying the final pressure. Inadequate or delayed aeration causes the formation of blowholes or porosity that compromise the mechanical properties and surface appearance of the part. In transfer and injection molding, volatiles escape primarily through the feed hopper and distributor runner (which must be heated to approximately 120°C to prevent premature gelation). Modern hot runner systems for thermosets manage this thermal balance precisely, enabling sprue-free processing and reducing material waste. 6. Recent news: Industry 4.0, Digital Twin and Artificial Intelligence in thermoset molding 6.1 The context of innovation The thermoset molding sector, traditionally more conservative than the thermoplastics sector, is experiencing a significant technological acceleration, driven by the adoption of Industry 4.0 enabling technologies. The reasons are clear: waste reduction, shorter start-up times, optimized curing parameters, and process traceability. 6.2 Digital Twin for monitoring the molding process The process digital twin is a dynamic virtual model of the molding system, fed in real time by data from sensors installed on the press, mold, and thermal conditioning system. For thermosets, where crosslinking kinetics depend nonlinearly on temperature, pressure, and time, the digital twin offers a unique advantage: it allows you to simulate the reaction progress without interrupting production and anticipate the onset of defects before they appear on the part. Studies published in 2024 and 2025 on liquid composite molding processes (RTM, VARTM) demonstrate that integrating sensors with surrogate models based on deep-learning neural networks allows for the detection of process deviations early enough to correct parameters before defects form. Similar systems are now being applied to compression and injection molding of conventional thermosets. 6.3 Artificial Intelligence and parameter optimization Machine learning-based optimization systems, such as those integrated into platforms like Moldex3D 2025 and similar systems, allow for the automatic definition of optimal process windows (mold temperature, pressure profile, curing time) from a limited number of physical tests. Moldex3D's AI Optimization Wizard, for example, manages multiple objectives simultaneously—cycle time reduction, distortion minimization, porosity control—generating compromise solutions that are validated virtually before any production testing. Predictive maintenance based on IoT sensor data analysis allows for scheduled interventions on presses and molds before failures occur, reducing unplanned downtime—a critical factor in production with long mold curing times. 6.4 Recyclability and circularity of thermosets: the state of the art The irreversible crosslinking nature of thermosets has historically posed an obstacle to material circularity. However, recent research indicates concrete progress: phenoplastic fillers—the most common thermoset molding compounds—can be ground into a powder and reintroduced as filler replacements into the virgin mass, with minimal property losses at concentrations of up to 13% regenerated material. For BMC applied to automotive valve covers, OEM specifications accept up to 7% regenerated material as a partial filler replacement. On the materials front, so-called vitrimers represent the most promising frontier: they are polymers with dynamic covalent bonds that allow controlled remelting at high temperatures, maintaining the mechanical performance typical of classic thermosets but allowing recycling and reshaping. 2025-2030 Outlook: The integration of process digital twins, predictive AI, and new semi-recyclable molding compound formulations will be the dominant innovation trajectory in thermoset processing for the automotive and power electronics industries. 7. Industrial applications: from traditional sectors to new markets Thermosets are used in a very wide range of applications, from classic electrical and electronic components (switches, sockets, winding supports) to structural components for the automotive and aerospace industries. Their irreplaceable characteristics include: heat resistance exceeding the deformation threshold of standard thermoplastics, long-term dimensional stability under load, excellent electrical insulation even at high temperatures, and resistance to aggressive chemicals. In the aerospace industry, thermoset composites with glass and carbon fiber (BMC, SMC, epoxy prepregs) are used for cabin panels, electrical system supports, and insulation panels, thanks to their ability to meet stringent fire, smoke, and toxicity (FST) resistance requirements. In the appliance industry, phenoplastic and aminoplastic injection molding allows for the production of oven handles, engine components, and heating element housings at competitive costs and cycle times compared to high-performance thermoplastics. For applications in aggressive environments—marine, petrochemical, food—the chemical resistance of thermosets (epoxy, phenolic, furan) allows the production of insulators for electrical distribution systems, supports for underwater pylons, fluid control systems and wear panels with life cycle costs significantly lower than those of equivalent metals. Frequently Asked Questions (FAQ) What is the main difference between thermosets and thermoplastics in processing? Thermoplastics can be melted and reformed multiple times: heat makes them plastic, and cooling solidifies them without altering their chemical structure. Thermosets, on the other hand, undergo an irreversible chemical cross-linking reaction during forming: once polymerized, subsequent heat does not melt them but degrades them. This means that the mold must be heated to harden the part (unlike thermoplastics, where the mold cools), and that the equipment must prevent the reaction from starting prematurely in the plasticizing cylinder. What is BMC and how is it processed? BMC (Bulk Molding Compound) is a thermosetting molding compound composed of unsaturated polyester or epoxy resin, short glass fibers (15–25%), mineral fillers, and additives. It comes in the form of a dense paste and is processed by injection or compression molding. It is widely used in the automotive industry (valve covers, alternator casings) and in household appliances (engine components, fans) due to its ability to combine lightness, mechanical strength, and thermal stability. Why does thermoset injection molding require special machinery? Standard thermoplastic molding machines operate with high-temperature cylinders to maintain the molten material. For thermosets, this approach would cause premature cross-linking in the cylinder, resulting in tooling failure. Thermoset molding machines maintain the cylinder at a controlled, low temperature (80–120°C) to maintain the flowability of the mass, while the mold is heated to 160–200°C to activate and complete cross-linking only in the mold cavity. What is the role of the digital twin in thermosetting processing? The process digital twin creates a dynamic virtual model of the plant, powered by real-time sensors. For thermosets, it allows for monitoring the progress of the crosslinking kinetics without production interruptions, predicting the onset of defects (porosity, distortion, incomplete filling) before they occur, and automatically optimizing process parameters. Companies that have implemented digital twin systems for molding report 25–35% reductions in start-up times and scrap reductions of over 40%. Can thermosets be recycled? Irreversible cross-linking makes recycling by remelting, as is the case with thermoplastics, impossible. However, alternative routes are possible: grinding into powder allows the material to be reintroduced as filler into the virgin mass (up to 7–13% without significant loss of properties for phenoplastics). Vitrimers, a new generation of thermosets with dynamic covalent bonds, allow remelting and reforming at high temperatures, opening up concrete prospects for full recyclability. How much does wall thickness affect cycle times? Wall thickness is the most critical dimensional parameter. For compression molding without preheating, curing time increases linearly with wall thickness: 6–8 minutes are required for 20 mm walls, compared to 1–2 minutes for 5 mm walls. For injection molding, the dependence on wall thickness is much less pronounced due to the improved thermal conduction of the injected mass under pressure—the cycle time remains essentially constant up to a maximum thickness of approximately 10 mm. Sources and References 1. Ehrenstein, GW – Technical University of Munich. Werkstoffe und Bauteile aus Kunststoffen. Reference text for paragraphs 4.3 (Transformation technologies, pp. 274–276). 2. MDPI – Journal of Manufacturing and Materials Processing (JMMP), 2024. “Digital Twin Modeling for Smart Injection Molding.” DOI: 10.3390/jmmp8030102. 3. Moldex3D / CoreTech Systems, 2025. Molding Intelligence: AI Revolution in Injection Molding. Technical report. 4. Plenco – Plastics Engineering Company. Processing Guide for Thermoset Phenolics. Data on regrind and phenoplast properties. 5. MCM Composites LLC, 2025. Thermoset Molding Technologies in Aerospace, Appliance & Electronics. Press Release, November 2025. 6. CompositesWorld, 2025. JEC World 2025 Highlights: Digitized Processes and New Materials. 7. ResearchGate / Fernández-León et al., 2024. Real-time monitoring and digital twin simulation of liquid-molding processes. 8. Business Research Insights, 2024. Global Injection Molding Market Report 2024–2033 (USD 365 Bn → USD 580 Bn, CAGR 4.74%). 9. Ci-Dell Thermoset Plastics, 2025. Thermoset Composites: Key Facts About Performance, Sustainability and More. 10. Tedesolutions.pl, 2025. Digital Twin for Injection Molding Machines – Simulation and Optimization.
SEE MORE
Polyacrylamide: Production, Applications in Polymers, Paper and Textiles and Recycling PerspectivesFrom Chemical Synthesis to Industrial Applications and Sustainability Challenges: A Journey into Polyacrylamide between Innovation and Circularityby Marco ArezioPolyacrylamide is one of the most versatile and widely studied synthetic polymers of recent decades.Produced from acrylamide, this substance has found widespread use in strategic sectors such as advanced polymer industry, paper manufacturing, and textiles. Its industrial history is closely linked to the search for increasingly high-performance materials, capable of meeting the demands of modern production without neglecting environmental issues related to sustainability and recycling.In this article, we will explore what polyacrylamide is, how it is produced, its most important applications in the polymer, paper, and textile sectors, and we will address the current challenges of its recycling from a circular economy perspective.What is Polyacrylamide?Polyacrylamide (PAM) is a water-soluble synthetic polymer obtained by the polymerization of acrylamide (CH₂=CHCONH₂), an organic compound derived from petrochemical processes. Its basic structure consists of a long chain of repetitive acrylamide units, with the possibility of modifying its chemical composition through copolymerization or variations in the lateral functional groups. This allows for a wide range of products, each with specific properties such as ionic charge, molecular weight, and water absorption capacity.One of the key features of polyacrylamide is its functional versatility: it can be produced in anionic, cationic, or neutral forms, depending on the intended application. This makes PAM extremely useful as an industrial additive, rheology modifier, flocculant, or binder.How is Polyacrylamide ProducedThe production of polyacrylamide begins with the synthesis of acrylamide, which can be obtained through catalytic hydration of acrylonitrile or through more sustainable enzymatic processes developed in recent years. The polymerization of acrylamide is then carried out in aqueous solution, using radical initiators (such as ammonium persulfate), and can be controlled to obtain different molecular weights and degrees of branching.The main production phases include:- Synthesis of acrylamide – via catalytic hydration of acrylonitrile, a process traditionally conducted on a large scale in the petrochemical industry.- Radical polymerization – acrylamide is subjected to polymerization in solution, suspension, or emulsion, in the presence of initiators, to produce long, linear, or cross-linked polymer chains.- Chemical modification (copolymerization or functionalization) – PAM can be modified during or after synthesis by adding ionic groups, functional molecules, or cross-linking agents to tailor its properties (for example, to increase affinity for specific ions or adjust viscosity).- Formulation of the final product – polyacrylamide is dried or packaged as a powder, beads, or concentrated solution.Continuous improvements in production processes aim to reduce the presence of residual acrylamide monomer, a toxic and potentially carcinogenic substance, thereby increasing the safety and sustainability profiles of finished products, especially for applications involving contact with food or people.Applications of Polyacrylamide in Polymers, Paper, and TextilesPolymer SectorIn the world of polymers, polyacrylamide is used both as a raw material for the production of advanced copolymers and as a functional additive. For example, copolymerization with other monomers (such as acrylic acid, acrylonitrile, diallyldimethylammonium chloride) allows for the creation of polymers with specific properties: greater hydrophilicity, surface charge, chemical reactivity, or thermal resistance.These copolymers are used in various applications, including:- Superabsorbent hydrogels (e.g., medical and hygiene sector): thanks to PAM’s ability to absorb large quantities of water and swell without dissolving.- Rheological additives and viscosity control agents: in paints, adhesives, drilling fluids, and personal care products.- Supports for chemical synthesis: as cross-linkers in resins or matrices for the separation of biomolecules in biochemical and biotechnology laboratories (polyacrylamide gel electrophoresis).Paper IndustryIn the paper industry, polyacrylamide is one of the most widely used additives to improve productivity and paper quality. It is employed as:- Retention agent: promotes the retention of fine fibers and fillers, reducing losses and increasing the yield of raw materials.- Drainage agent: accelerates water removal during sheet formation, optimizing production times and reducing energy consumption.- Mechanical properties enhancer: cationic polyacrylamide binds to cellulose fibers, increasing both the dry and wet strength of paper, as well as improving surface quality and printability.The use of PAM has enabled paper mills to become more efficient, lower operational costs, and reduce environmental impact by decreasing water consumption and the emission of residual sludge.Textile SectorIn the textile sector, polyacrylamide is mainly used as a thickener and binder in printing pastes and as an auxiliary in the treatment of wastewater generated by dyeing and finishing processes.The main functions include:- Thickener for printing pastes: improves the precision and definition of designs on fabric due to its ability to increase the viscosity of pastes without interfering with dyes.- Binder for fibers and pigments: promotes the adhesion of pigments or additives to fibers during printing or surface treatment stages.- Flocculant in purification treatments: allows for the effective removal of pollutants and suspended particles in wastewater, facilitating water recycling in textile processes.The result is improved final textile product quality, reduced consumption of raw materials, and greater sustainability of the production cycle.Recycling and Sustainability of PolyacrylamideThe issue of polyacrylamide recycling is complex and the subject of ongoing scientific research. As a highly stable and poorly biodegradable synthetic polymer, PAM does not easily lend itself to traditional mechanical or chemical recycling methods as do other more common polymers (such as PET). Nevertheless, studies are underway to find innovative solutions that minimize its environmental impact.The main strategies currently being examined are:- Recovery and reuse in industrial processes: in the paper and textile industries, sludges and residues containing PAM are partially recovered and reused as additives in other stages of the production process or as conditioners for sludge dewatering.- Advanced degradation: research is focusing on catalytic degradation technologies, advanced oxidation (UV, ozone, hydrogen peroxide), and biological methods using engineered microorganisms capable of attacking the polymer chain, although on an industrial scale these processes are still limited.- Development of biodegradable polyacrylamides: some companies are investing in the synthesis of copolymers with biodegradable segments or biopolymers that can replicate PAM’s functions but offer greater end-of-life sustainability.From a regulatory standpoint, the management of waste containing polyacrylamide is governed at European and national levels, with particular attention to minimizing residual monomer content and implementing safe recovery and disposal systems.ConclusionsPolyacrylamide is a key element in polymer chemistry and modern industrial applications, especially in the fields of functional polymers, paper, and textiles. Its ability to optimize production processes, enhance material properties, and facilitate water treatment makes it a valuable ally for sustainable production.However, challenges related to recycling and environmental sustainability require close attention to the development of new solutions to close the life cycle of these polymers and reduce the environmental impact of industrial processes.© All Rights Reserved
SEE MORE
Additive Manufacturing for Reinforced Polymers: 3D Printing Meets Composite MaterialsHow 3D Printing with Reinforcing Fibers Is Transforming the Advanced Plastics IndustryWhen we think of 3D printing, we often imagine a world of prototypes, quick models, and lightweight plastics designed for shape or function testing. But that image is now outdated. Additive manufacturing has evolved into a robust tool for industrial production—capable of producing finished parts that are strong, reliable, and high-performing.Among the most promising developments in this field is the use of fiber-reinforced polymers, composite materials that combine lightness and mechanical strength with durability and customizability. It’s a major transformation—not only in engineering terms but also from an environmental perspective. As the world urgently seeks sustainable alternatives to conventional manufacturing, the ability to 3D print reinforced materials with precision, efficiency, and flexibility opens entirely new scenarios.Polymers and Fibers: An Alliance for the Future of ManufacturingAt the core of this revolution is the meeting of two worlds: that of thermoplastic polymers—ductile, versatile, and lightweight—and that of high-performance fibers, such as glass, carbon, or aramid, known for their superior mechanical properties. The combination of these materials yields structured composites that outperform traditional plastics in tensile strength, bending resistance, wear, and chemical durability.In the past, such composites were mostly available in laminated form or manufactured using compression molding. Today, however, new additive manufacturing technologies allow these materials to be directly 3D printed, with increasing sophistication. This unlocks a level of control over form, internal structure, and fiber distribution that was previously unthinkable.Two Paths, One Goal: Enhanced Performance Without Losing FlexibilityThere are two main approaches to 3D printing fiber-reinforced materials. One involves filaments pre-filled with short fibers: these spools contain a polymer matrix blended with micro-fiber fragments that enhance the mechanical properties of the final part without affecting printability. This method is relatively simple and compatible with many FFF (Fused Filament Fabrication) printers, making it an accessible entry point into the world of composites.The second, more advanced method uses continuous fibers. Here, the printer is engineered to co-extrude long fibers along with the polymer, effectively “weaving” reinforcement directly into the part. This approach requires specialized machinery and advanced slicing software, but it enables the production of truly structural components, with performance levels comparable to certain industrial laminates. For example, a carbon fiber-reinforced plastic bracket printed using this method can be lighter and stronger than its metal equivalent.Beyond the Technology: Environmental and Industrial BenefitsThe true value of these materials goes far beyond lab test data. The ability to print only what is needed, with minimal waste, significantly reduces environmental impact. On-demand production eliminates the need for lengthy logistics, bulky storage, and energy-intensive processes. Tooling costs are lowered, and time-to-market is shortened—an essential factor in all competitive sectors.Moreover, many manufacturers are already experimenting with bio-based filaments or recycled plastic content, and carbon fibers reclaimed from industrial waste are starting to become a viable resource. All of this positions reinforced additive manufacturing as a technology fully aligned with the principles of the circular economy—combining high performance with environmental responsibility.Expanding Applications: From Aerospace to ConstructionApplications for this technology are rapidly multiplying. In aerospace, for example, fiber-reinforced 3D printing is used to create lightweight brackets, custom ducts, and vibration-resistant components—cutting weight and, in turn, energy consumption. In the automotive sector, it's applied to functional prototypes and even small production runs, particularly for electric or sports vehicles.In the fields of robotics and mechatronics, printed composites are used in mechanical arms, levers, and structural components that must be both lightweight and robust. Even in construction, interesting applications are emerging, such as modular joints, structural connectors, or architectural elements that combine function and aesthetics in a single production process.A Challenge of Skills, Quality, and MaterialsNaturally, 3D printing with reinforced materials comes with its own challenges. The bond between the fiber and the polymer matrix is critical, requiring material research and careful tuning of print parameters. Proper fiber orientation is also vital—placing fibers incorrectly can compromise the entire functionality of the part.Another key issue is process repeatability: for parts that must meet certified performance standards, consistent results across multiple batches are a must—something that remains complex with current systems. Finally, the cost of materials, especially those with continuous fibers, remains relatively high, though it is gradually decreasing as adoption grows.The Future Is Custom, Sustainable, and DigitalLooking ahead, it’s clear that this technology will not only continue to grow but fundamentally change how we think about manufacturing. Emerging trends include integration with generative design algorithms, which suggest optimal shapes and reinforcement paths based on expected loads. Materials will become increasingly eco-friendly, and distributed manufacturing—potentially directly at local workshops or maintenance centers—will soon become a reality.In this context, additive manufacturing with reinforced polymers is more than a technological promise. It is a real tool for creating lighter, more efficient, and more sustainable products. A concrete lever for circular industry, aiming to do more with less: less material, less energy, less waste. But also more innovation, more precision, and more design freedom.© Reproduction Prohibited
SEE MORE
Rotational Molding: Why is Powder Size Important?There are many factors that influence the quality of a product, one of these is the choice of powders. The rotational molding is a process frequently used for the formation of objects, using thermoplastic resins , that we need to be hollow. The main feature of the process is that the mold rotates around two axes, or mutually perpendicular, moreover, with respect to injection molding traditional, the raw material, in the form of powder, is introduced into the mould, to then be heated and subsequently cooled. What are the main differences with the injection molding process? Perhaps the most obvious is that in rotational molding the raw material is used in the form of powder and not granules furthermore, the polymeric resin is found inside the closed mould, and not pressure injected into it. Furthermore, the mould, in the rotational process, works on the basis of axial rotation unlike the static nature of injection moulding. Finally, we can say that rotational process molds are cheaper as they do not have to consider the injection pressure. Why choose rotational molding? When objects with a hollow shape have to be produced, rotational molding is particularly suitable for its ease of adaptation to all required forms. Furthermore, in the absence of great pressure inside the mould, the product tends to easily shrink and detach after its production, even if the objects are of large size. Finally, we can say that through the rotational process, it is also possible to create very complex elements both from a structural and design point of view. Main characteristics of rotational molding molds We can say that the main materials that make up the molds are: • Cast aluminium • Electroformed nickel • Stainless and non-stainless steel When we are faced with the need for better uniformity in the heat exchange inside the mould, we will choose cast aluminium. If we had to favor a faithful reproduction of the figures we could choose electroformed moulds, while in the presence of simple shapes and large formats, we can opt for the cheapest steel moulds. If we talk about the thickness of the molds we can say that, normally, the cast aluminum molds have a thickness of 6-8 mm, while those in steel only 2- 3mm. When designing the mold you should always keep in mind which raw material you will be using, as some polymers shrink sufficiently facilitating the extraction of the piece, others less, so as to make a slight draft angle necessary in the mold to facilitate the detachment of the product. Rotational molding phases As we said previously, rotational molding is nothing more than a heat exchange within a mold under conditions of movement. The temperatures during the process can vary, within a certain range, continuously during the entire production cycle. Despite these continuous variations in temperature, the quality of a product is established by calculating the exact permanence of the mold inside the oven. This time is called induction time. We can therefore say that, in the first phase of the cycle, the induction time is that interval of heating of the mold in which the resin reaches melting temperature, which normally takes place through the blowing of hot air. The induction time is characterized by the following variables: • Oven temperature • Speed of heat exchange • Thickness of the mold • Melting temperature of the resin • Ratio between surface and volume of the mold • Thermal transfer coefficient of the mold material The second phase of the cycle, defined melting time , is the time required to completely melt the resin. The melting time is characterized by the following variables: • Thickness of the piece • Temperature of the resin and heat of fusion • Mold heating capacity • Ratio between the surface of the mold and its volume • Oven temperature All of these variables have a significant impact on melt time and quality of the piece to be made.However, the melting speed of the resin can, in some cases, be increased by raising the oven temperature, but it is important not to exceed in this operation because, if on the one hand it increases productivity, on the other an excessive permanence of the polymer in the mold, at very high temperatures, can lead to its degradation. Choosing the powder to be used for rotational molding As we have seen, the melting time of the resin is a crucial factor for the good performance of the mold and for the quality of the pieces to be produced. So, we can say that even the size of the polymer particles that are used can influence the processo. In fact, a dimensionally larger resin increases the time needed to melt. This occurs due to the decrease in contact surface between the particles and the hot parts of the mold, but this does not normally occur if a raw material size of less than 500 microns is used. Beyond the important dimensional parameter of the polymer powders to be used, it can be said that a good raw material is one that flows quickly into sharp corners and in the recesses, adhering to the mold and melting without bubbles through the thermal contribution. Moreover, from experience, the finest powders are used for resins with lower MFIs, in order to obtain a good surface reproduction, while the use of a polymer with high MFI may consider using larger particle sizes. Cool cycle of the mould The cooling of the mold and the product can take place through the use of both air and water. Normally the air, pushed by the cooling fans, hits the outside of the mold, while the use of water jets is reserved for the inside. The cooling time is very important as an acceleration of this phase, therefore a rapid cooling, could lead to a deformation of the piece with an increase in the percentage of the amorphous phase of crystalline polymers. Machine translation. We apologize for any inaccuracies. Original article in Italian.
SEE MORE
Submarine Telecommunications Cables: Structure, Materials, Production, Laying, Durability and RecyclingFrom High-Density Polyethylene to Polyurethane: How Submarine Cables Are Made, Laid, and How Long They Lastby Marco ArezioSubmarine telecommunication cables are the backbone of global data traffic, enabling the Internet and telephone networks to connect distant continents.Despite their often invisible image, submarine cables are essential for keeping the world connected.But how are they made? What materials are used, and how do they manage to last so long in the harsh ocean environments?Let’s explore these aspects with a particular focus on the polymers used and their functions.Structure of a Submarine Telecommunications CableThe structure of a submarine cable may seem simple, but it is a technological marvel designed to withstand enormous pressures and harsh environmental conditions.At the core of the cable are the optical fibers, which carry signals in the form of light, allowing for the transmission of vast amounts of data. These fibers are incredibly thin and fragile, so they must be protected by several layers of materials.The fiber core is surrounded by a protective polymer coating, usually made of an acrylic polymer. This layer is crucial for maintaining the integrity of the fibers, preventing them from being physically damaged or coming into contact with moisture.Between the optical fibers and the cable’s subsequent layers, a waterproof gel is often used as an additional barrier against water ingress.As protective layers are added, we find a metal sheath, generally made of steel or aluminum, to protect the cable core. This metal layer is corrosion-resistant and prevents the cable from being damaged by external pressures, impacts, or even bites from marine creatures.The final coating of the cable is made of polymeric materials, which offer the outermost protection and determine its longevity in deep-sea conditions.Polymers Used in Cable ConstructionOne of the main materials used in the construction of submarine cables is high-density polyethylene (HDPE). This polymer is widely used because of its properties: it is water-resistant, chemically stable, durable, and relatively cost-effective to produce.As a thermoplastic polymer, HDPE is also easy to shape and work into thin or thicker layers, depending on the structural needs of the cable. In addition to its insulating function, HDPE is crucial for protecting the cable from wear caused by ocean currents, sand, and underwater debris.Another key polymer is polyurethane, mainly used as an external coating in cables destined for particularly extreme conditions, such as volcanic zones or areas of high seismic activity. Polyurethane is elastic and has high abrasion resistance, two characteristics that make it ideal for protecting the cable from potential physical damage.Besides the main polymers like HDPE and polyurethane, other polymeric materials, such as acrylic resins, are used in the inner coatings that wrap around the individual optical fibers, protecting them from moisture and minor shocks that could compromise their functionality.Finally, in certain specific applications, materials like polypropylene may be used, offering superior chemical resistance and sometimes preferred in cables laid in particularly chemically aggressive waters.Submarine Cable ProductionThe production of a submarine cable is an extremely complex process, divided into several stages. First, the optical fibers, the true stars of data transmission, are produced. These fibers are created through a process known as drawing, in which a preform of glass is heated and stretched into a thin thread.Once ready, the fibers are wrapped in acrylic polymers to protect them from physical damage. Next, layers of steel or aluminum are added for protection.These metallic materials are essential for shielding the cable from external forces and corrosion. The entire core is then covered with multiple layers of HDPE or polyurethane, depending on the cable’s requirements and the conditions it will face.Before being shipped for underwater installation, the cables undergo rigorous testing to ensure they can withstand the enormous underwater pressures and mechanical stresses they will encounter throughout their long operational life.Laying of Submarine Telecommunications CablesLaying a submarine cable is an operation that requires meticulous planning and highly specialized equipment. The first step is mapping the seabed, an operation that involves the use of sonar and other detection tools to find the optimal path.Cable-laying ships, large vessels equipped with advanced technology, are tasked with slowly releasing the cable onto the seabed, avoiding any damage during the process.In some areas, where the seabed is particularly rugged or where there is a risk of collisions with other infrastructure or human activities, underwater plows are used to dig a trench in which the cable is laid. This operation allows the cable to remain protected from potential impacts or accidents.Once the cable reaches the shore, it is connected to terrestrial infrastructure and tested to ensure everything functions properly.Cable Lifespan and MaintenanceSubmarine cables are designed to last between 25 and 30 years, although their lifespan may vary depending on environmental conditions. Some cables may require maintenance before the end of their operational life, especially in areas with intense human activity, such as fishing or maritime traffic.Maintaining a submarine cable is a delicate operation. If a fault occurs, specialized ships are sent to locate the damaged point, raise the cable from the ocean depths, and repair it on the surface. This process can be very costly and time-consuming, but it is essential to ensure the continuity of global communications.Recycling Submarine Telecommunications CablesOnce a submarine cable has reached the end of its useful life, the question of recycling arises. Traditionally, many cables were left on the ocean floor, but today, with growing attention to sustainability, there is an increasing effort to recover and recycle these infrastructures.The recycling process begins with recovering the cable from the seabed, an operation similar to laying it. Once brought to shore, the cable is transported to specialized facilities where it is separated into its components.Metals such as copper and steel are recovered and reused in new production processes, while polymers can be recycled or, in some cases, used for energy recovery.Recycling submarine cables is an important step towards creating a circular and sustainable economy, minimizing the environmental impact of telecommunication infrastructure.ConclusionsSubmarine telecommunication cables are technological marvels. Constructed with advanced materials like HDPE and polyurethane, these cables are designed to last for decades in the ocean's depths, transmitting vital data and communications for the global economy.Despite their complexity, the future of submarine cables is increasingly looking towards a sustainable approach, focusing on recycling and the use of materials that can be recovered and reused effectively.
SEE MORE
Recycled EPDM: Where it Come from and What it IsLet's see what EPDM polymers are, those mixed with PP and what are the sources of their recycling. In the world of polymers, rubber EPDM is defined, terpolymer, because it is obtained from the copolymerization of ethylene, propylene and a diene monomer. In the analysis of EPDM components, the value of ethylene can be represented by a percentage ranging from 45 to 75 This percentage range affects the characteristics of the rubber mixture, in fact the higher the percentage of ethylene, the better the workability, loading and extrusion will be. Regarding the peroxide-based vulcanization of EPDM rubber compounds, these are characterized by a higher cross-linking density than other similar polymers. EPDM also lends itself very well to blends with polypropylene, as it has a stiffness and a high softening temperature, compatible with both polymers.The technical characteristics of the blends between PP and EPDM depend on the degree of mixing of the components, in fact, with a percentage of PP around 90% the same technical characteristics of the original PP are obtained, but with a lower stiffness and softening temperature. On the other hand, the blends that contain a percentage of PP around 40% will have the typical characteristics of a thermoplastic rubber. Furthermore, the choice of the type of polypropylene, whether homopolymer or copolymer, will change the final characteristics of the mixture. What are the properties of EPDM? EPDM products have good resistance to hot and cold water, heat resistance, ozone resistance, weather resistance and steam resistance . On the other hand, they have low resistance to petrol, kerosene, aliphatic aromatic hydrocarbons, solvents and concentrated acids. What are the uses? The most common use of EPDM is certainly the automotive sector, where it is used for the following main products: • door seals • windows • trunks • windscreen In the construction sector: • roof membranes • geomembrane for ponds • mixed with polyurethanes they are used on floors, roofs, asphalt, brick and wood • to create non-slip floors • seals for fixtures In the household appliances and systems sector: • refrigerators • radiators • straps • washing machines • pipes • electrical insulation How to recycle EPDM EPDM products can derive from the industrial sector, expressed in processing waste, or from the civil sector, as waste from differentiated collection. In both cases, the objects to be recycled must be previously analyzed as they may contain materials other than EPDM alone. For example, the recycling of car bumpers must be preceded by a process to remove any data or screws that could be contained in the product, or, in the post-consumer field, the bumpers could present harmful paints to the final quality of the raw material to be recycled. Furthermore, often, in the automotive industry, EPDM components could have insulators attached such as, for example, the cross-linked polyethylene which worsens the quality of the waste to be processed. Recycled EPDM is normally used in the form of ground material in various dimensional shapes, but also as a granule suitable for extruders or injection molding machines.Automatic translation. We apologize for any inaccuracies. Original article in Italian.
SEE MORE
Clamping Forces in Injection Molding: Technical Analysis and OptimizationInternal Pressures, Mold Clamping Force Optimization, and Advanced Methods for Improving Quality and Efficiency in Plastic Injection Moldingby Marco ArezioInjection molding is a widely used technology in manufacturing industries for producing plastic components, appreciated for its ability to create parts with complex geometries and highly precise dimensions. Among the most critical technical aspects of this process, managing mold closure forces plays a fundamental role. When properly managed, these forces help ensure consistent product quality, reduce operational costs, and enhance the overall production efficiency of manufacturing plants.The Injection Molding ProcessInjection molding follows a well-defined sequence of operations. Initially, the plastic material is heated until it reaches a molten state. Then, the molten plastic is injected into the mold cavity via a specialized feeding system. Following this, a pressure-holding phase occurs, crucial for counteracting the natural shrinkage of the material as it cools, thus ensuring dimensional stability.Once the cooling and solidification processes are complete, the finished component is extracted from the mold. During the initial injection phase, the high pressures generated inside the mold tend to separate the two mold halves. Therefore, a counteracting force, called mold closure force, is essential to maintain the mold tightly closed throughout the production cycle.Concept and Importance of Mold Closure ForceMold closure force is defined as the force exerted by the injection molding machine to firmly hold together the two halves of the mold during the injection process. Properly managing this force prevents accidental mold opening, thus avoiding common defects such as flash, dimensional inaccuracies, or surface defects in the final product. Precisely calibrating the mold closure force ensures reliable production while minimizing energy consumption and extending the lifespan of molds and machinery.Analysis of Internal Pressures in the MoldDuring injection, the mold experiences high internal pressures that depend on various operational and material parameters, such as the type of polymer used, its rheological properties, processing temperature, injection speed, and the geometric complexity of the mold cavity. Typically, the maximum pressure occurs near the gate, the material entry point, and gradually decreases along the flow path of the polymer.A detailed analysis of pressure distribution using advanced tools and software allows precise determination of the required force to keep the mold correctly closed throughout the injection process.Method for Calculating Mold Closure ForceAccurately determining the mold closure force required in injection molding involves a simple mathematical relationship:F = P × A × KWhere:P is the average pressure recorded inside the mold during the injection phase;A is the maximum projected area of the molded component, i.e., the surface perpendicular to the direction of the mold closure force;K represents a safety coefficient, usually ranging between 1.1 and 1.5, accounting for possible pressure fluctuations during the production process.Strategies for Optimizing Mold Closure ForceOptimizing the mold closure force is crucial for improving the final product's quality and reducing production costs. Among the main strategies adopted are advanced numerical simulations (CAE), which precisely predict polymer behavior during injection and optimize mold design accordingly. Additionally, adaptive control technologies based on sensors and intelligent systems dynamically and automatically adjust the closure force during the process, adapting in real-time to changing operational conditions. Careful mold design, focusing on reducing the projected area and strategically positioning injection gates, further helps decrease internal pressures and consequently the required force.Results and Benefits of OptimizationExperimental studies and industrial applications confirm that correctly optimizing mold closure forces provides significant benefits, such as reduced energy consumption, improved dimensional and aesthetic quality of products, and extended mold life. Additionally, optimized management of closure forces significantly reduces extraordinary maintenance interventions and downtime related to mold replacement, thus increasing overall productivity.ConclusionsAccurate management of mold closure forces in injection molding is not merely a technical requirement but also a strategic factor in improving industrial competitiveness. Integrating advanced technologies, precise simulations, and careful mold design can lead to excellent results in terms of product quality, energy efficiency, and cost containment. This demonstrates the critical importance of correctly optimizing forces in the injection molding process.© All Rights Reserved
SEE MORE
Plastic Polymers in the Footwear Sector: Materials and UsesPlastic Polymers in the Footwear Sector: Materials and Uses The plastic industry has created an important space for itself in the field of soles and footwear which until a few decades ago were exclusive to leather and other minor materials. The creation of new recipes, the chemical and technological progress on the systems, has allowed plastic polymers to create a valid alternative to traditional soles to be used in footwear subjected to heavy wear, with a protective value for the foot, thermal insulation, flexibility and impermeability. In addition to the growth of new formulations made with virgin polymers, the recycled polymer market is offering different alternatives through sustainable products especially in the field of PVC and ABS. The plastic materials that are mostly used in the footwear sector are: Thermoplastics: ABS, PVC, TR and TPU Bi-component polyurethanes: PUR based on polyether, PUR based on polyester Copolymers such as rubber and EVA Let's see in detail the features and applications: ABS Although ABS is not a commonly used polymer in footwear, it is often used in safety footwear, as a protective element for the toe of the shoe. The tip, in fact, is often made of recycled ABS, from post industrial waste, whose recipe is adapted to give the tip strength to shocks and flexibility. TR or Thermoplastic Rubber With this material it is possible to manufacture soles to be applied or inserted into the shoe by direct injection. Thermoplastic rubbers are compounds whose fundamental component is styrene-butadiene-styrene (SBS) added with oils, polystyrene, mineral fillers, pigments, antioxidants, etc. . Through a correct formulation of the recipe of the material, the soles do not have problems with resistance to cold and can maintain excellent flexibility at temperatures much lower than 0 ° C. PVC, Plasticized Polyvinyl Chloride PVC is one of the most popular plastic materials in the world, not only in the footwear sector, but is also used for the creation of doormats, carpets, wires, pipes , water reeds and many other products. In the waterproof footwear sector, such as boots, soles, sandals, slippers and accessories, PVC has found a wide use as a material in continuous technological development, having reached a good level of environmental efficiency today and ensuring good safety in all phases of its life cycle. In fact, in the footwear market, there are important volumes of products made of recycled PVC that allow the construction of sustainable soles and footwear, therefore recycled and recyclable. TPU, Thermoplastic Polyurethane TPU is a chemical compound made up of polyurethane elastomers treated with the techniques of thermoplastic materials. Its realization goes through the isocyanate addition process, in a certain temperature range, recreating the elastic characteristics of the rubber. Thermoplastic polyurethanes are used for different types of soles intended for certain segments of footwear such as sport, work and leisure. The formulas that characterize the materials for TPU soles change according to the type of use of the same and consequently of the shoe. PUR, Bi-Component Polyurethane Polyol and Isocyanate, in liquid form, which are part of the Polyethers and Polyesters families, are two chemical elements that characterize the formation of Bicomponent Polyurethane . The difference between these two classes is based on the structure of the foam that will be created, in fact, using the polyether a compact surface skin is created and, inside, the sole will have open cells, while using polyester a structure with closed cells will be created. Eva, Ethyl vinyl Acetate Ethylene and Vinyl Acetate are the two main components of the polymer called EVA, a polymer used for the construction of soft and resistant soles. The sole, however, is not constituted only by the two components that form the main polymer but, through the correct calibration of these elements and of crosslinkers, fillers, expanding agents, and more, the performance characteristics of the final product are determined. The main characteristics are lightness, flexibility, elasticity and a good propensity to keep the original shape. Composite Materials The evolution of fashion, technical needs and the general costs of the finished product have allowed the creation of materials composed of different but similar polymers. Polyurethane materials, rubber and EVA are the main polymers that are used with the aim of creating different combinations in terms of aesthetic appearance, costs and of technical use, surprisingly widening the offer on the market. Characteristics of finished products The study and realization of new polymer recipes, for the creation of new commercial opportunities, must not make us forget that the footwear and the soles themselves must respond to well-defined characteristics for the end customer. There are specific regulations that must be respected in the construction of a product for the footwear sector, in which it is requested that the articles be subjected to behavior tests. Let's see the main ones: Resistance to bending Resistance to abrasion Resistance to delamination Slip resistance Dimensional stability Resistance to aging Compressive strength Bonding capability Tensile strength Resistance to water penetration Holding capacity of the stitch Automatic translation. We apologize for any inaccuracies. Original article in Italian.
SEE MORE
Polymeric Coatings for Metal Food PackagingPolymeric Coatings for Metal Food PackagingMetal boxes for food preservation have a long history but, if in the past, they had deficiencies from the hygienic and toxicological point, especially in because of the welds that were made in Sn-Pb alloy, currently the quality of the manufactured products are much better. Today the protection of food is mainly entrusted to the polymeric layer of inner coating , called coating , which stands between the metal wall and the contained food. The primary function of this barrier is to protect food products from light, oxygen, enzymes, humidity, pollutants and microorganisms that would result in the modification of the structure of the food and its quality. The aim is also to increase the useful life of the food or the drink which in normal, that is, not canned, it would deteriorate more quickly, as the biochemical and enzymatic reactions and the activity of microorganisms would normally run their course. Therefore, to increase the life of the food, the metal packages are normally coated with synthetic resin film applied to the metal sheet again flat, film with a thickness of a few microns. The choice of the type of resin depends on its mechanical, chemical or thermal characteristics based on the content they must host. Below we can list the main ones: • Rosin consists mainly of abietic acid, which is normally added with ZnO to control the chemical reactions that are formed through the sulfur amino acids of proteins. • Vinyl resins are from the family of thermoplastic resins, normally PVC, which have excellent resistance to acids, but have the defect to absorb food pigments. • Phenolic resins are composed through the polymerization of formaldehyde and phenol which have excellent resistance to heat treatments, PH and to fats. Through the formaldehyde content we can identify two families of phenolic resins: Novolacche (thermoplastic) and Resoli (thermosetting). • Epoxy Resins are thermosetting resins consisting of bisphenol A and epichlorohydrin which are the most common coating in canned foods, especially in fish-based foods in oil. • Polyester resins are thermosetting resins obtained from different monomers such as phthalic anhydride, maleic anhydride or fumaric acid, integrated with vegetable oils and pigments. They have the characteristic of flexibility giving this characteristic to the metal wall layer. • Epoxy-Phenolic Resins are the result of the polymerization of epoxy resins with phenolic ones through catalysts. They are used as a transparent coating for many metal cans that contain oil, vegetable or pet food preserves. As regards the toxicological characteristics there are specific legal regulations that place limits on the possible migration of packaging substances into food, in which both specific migration and global migration are considered. However, the scientific community has given new impetus to studies and research on the toxicological aspects relating to plastics used in the food industry, with particular attention no longer to the single element that constitutes the packaging, but takes into consideration the cocktail effect that is given by all the elements that come into contact with food translated over time and with different thermal characteristics. Undoubtedly the food or drink contained in the packaging at the time of packaging has certain characteristics, but over time and in different climatic conditions , the quality of the food that arrives on the table could be different. Therefore it would be advisable to verify it through a chemical analysis, on a sample, with an instrument composed of a gas chromatograph and a spectrometer ion mobility that, in a simple and rapid way, will give the photograph, analytical, of the quality of food or drinks. Automatic translation. We apologize for any inaccuracies. Original article in Italian.
SEE MORE
The degradation of recycled polymersWhat is meant by degradation of recycled polymers: biological, oxidative, photo-degradation and thermal?In the years since the post-war period, plastics have increasingly taken the market by replacing products made with other types of materials as the countless advantages that this new material brought were immediately highlighted. Among the advantages of the plastic materials that can be underlined, we find the lightness, the ease of processing, the possibility of coloring and the low production cost. In fact, in those years we concentrated on the undisputed advantages of plastics without investigating the issues that determined their degradation . Today, with the great experience that users and manufacturers of plastics have acquired, we can balance the advantages and disadvantages of such an innovative material. We can classify the disadvantages between internal and external: Internal disadvantages chemical and physical modification polymer production process chemical reactivity of additives External Disadvantages thermo-hygrometric variations UV exposure pollutants heat microorganisms oxygen accidental causes Furthermore, degradation can be physical or chemical . In physical deterioration, an increase in crystallinity and consequently in density can be noted, with the emergence of internal tensions, cracks and deformations. The chemical one, which occurs at the molecular level, based on the degrading agent, affects the polymer chains with a loss of cohesion and a decrease in molecular weight.OXIDATIVE DETERIORATION Although the degradation of organic and inorganic polymers under the effect of oxygen is very slow, this causes the release of chemical substances that lead to the self-catalyzation of the polymer itself, that is, the chemical agents resulting from degradation in turn attack the polymer chain, activating a self-destructive process. Furthermore, if this phase is affected by the formation of free radicals by the action of heat or light , then the reaction between the polymer and oxygen increases the rate of cleavage of the chains, which leads to crosslinking and the formation of volatile elements. This process is called photo-oxidation or thermo-oxidation, depending on whether the trigger was light or heat. The direct consequences on the quality of the polymer can be seen through the reduction of the mechanical properties, especially with regard to elasticity and breaking strength. ORGANIC DECAY By biological degradation is meant the attack by fungi and bacteria on some polymers , especially those of natural derivation. These are subject to the phenomenon of hydrolysis , which can expose the polymer, in the presence of a high rate of humidity, to the breaking of the chains. To stop degradation, you can opt for storage in an oxygen-free environment, but you need to know the origin of the polymer well as it is not a universally valid treatment. THERMAL DETERIORATION The phenomenon of thermal degradation is caused by the presence of mobile hydrogens in the chain or by the radical activity that are triggered by heat, causing the chain to break with the formation of breaks and the production of volatile elements. The lack of oxygen leads to the depolymerization of the chain which occurs in three dissociative phases: initiation, molecular transfer and propagation. To increase the chemical resistance of the polymers to thermal degradation, the best solution is to add additives during production. PHOTO-DEGRADATION The photo-degradation phenomenon occurs when the polymer is subject to the influence of UV rays in the wavelength range between 290 and 400 nm. At the atomic level, we know that light radiation functions as a flow of particles, specifically photons , which, coming into contact with the molecules of materials and, under certain conditions, can interact passing from a state of low energy to one with high energetic excitation. . These particular flows and movements are defined as photo-physical and / or photo-chemical . In the first case, there are no chemical modifications between the polymer molecules, while for the photochemical process, there are possibilities that the molecules alter their chemical characteristic by virtue of the presence of abundant energy. In some synthetic macromolecules, the energy of the photons contained in UV radiation have the power to cause breakage of the covalent bonds. Automatic translation. We apologize for any inaccuracies. Original article in Italian.
SEE MORE
