- The strategic role of pre-treatments in the plastic recycling chain
- Types of contamination in post-consumer plastic waste and their impact on extrusion
- Cold washing: hydrodynamic action, process parameters and water management
- Hot washes: detergents, temperatures, pH and removal of grease, glues and inks
- Flotation, chemical baths and density separations: selective purification of polymer streams
- Drying technologies for PET, PE, PP and polyamides: moisture control and hydrolytic degradation
- Degassing and odor reduction: VOC management and requirements for high-value markets
- Prevention of thermal degradation: integration between pre-treatments, process parameters and formulation of the recycled material
How cold and hot washing, chemical baths, density separations, drying and degassing stabilize the polymer and define the industrial quality of recycled plastics
Essay. Recycling of Post-Consumer Plastics. Chapter 8: Pre-treatments and Cleaning of Post-Consumer Plastics: Washing, Flotation, Drying and Odour Control in Mechanical Recycling
In the post-consumer plastics recycling chain, pre-treatments are the invisible backbone that supports the quality of the material entering the subsequent stages of extrusion and compounding. If collection, sorting and characterization make it possible to identify and separate the nature of polymers, it is through washing, removal of impurities, thermal stabilization and drying that waste is transformed into a material that is technically suitable for regeneration. Without adequate pre-treatments, the selected plastics would remain a heterogeneous and contaminated mass, lacking the consistency needed to ensure processability, rheological stability and reliable physical-mechanical properties.
Pre-treatment has a precise task: to reconvert a dirty, unstable, contaminated and often degraded material into a polymer capable of withstanding thermal stresses without generating undesired phenomena such as odours, viscosity instability, black specks, oxidative degradation or colour variations during melting.
It is a process that acts on several levels: mechanical and organic cleaning, removal of light or foreign fractions, control of internal moisture, reduction of volatile compounds, prevention of thermal degradation and chemical stabilization of the polymer.....© Reproduction Prohibited
