Discover what mono- and biaxially oriented PLA films are, how they are produced, how they differ from PP, PET, and PE, their most innovative applications, and the challenges of recycling

by Marco Arezio

In recent years, the plastics sector has undergone a true revolution, driven by the growing demand for sustainable solutions and regulatory pressure aimed at reducing traditional fossil-based packaging.

At the center of this transformation is PLA (polylactic acid), a bioplastic derived from plant sources that today stands out as one of the most promising materials for the future of flexible packaging.

However, not all PLA is created equal: among the most interesting innovations are the oriented films, both monodirectional (MOPLA) and biaxial (BOPLA), which are gaining traction among producers and brands with a focus on environmental sustainability.

What is PLA and why is it considered revolutionary?

PLA is produced by fermenting sugars extracted from plant biomass, such as corn or sugar cane. Once lactic acid is obtained, it is polymerized and transformed into granules, which can then be extruded into thin, transparent films. PLA is renowned for its industrial compostability: under controlled conditions, it can decompose within a few weeks, returning water, carbon dioxide, and biomass to the environment—without leaving behind microplastics.

Moreover, its chemical structure, based on a relatively rigid polymer chain, gives it high transparency and a good aroma barrier, making it suitable for numerous packaging applications.

The importance of film orientation: MOPLA and BOPLA

To meet the needs of more advanced markets, PLA is often subjected to an orientation process that enhances its performance.

MOPLA film is stretched in a single direction (usually along the machine direction), resulting in films that are stronger and stiffer along that axis—ideal for products like adhesive tapes, labels, or packaging that requires specific directional strength.

BOPLA technology, on the other hand, involves orienting the film both longitudinally and transversely. This double stretching process drastically increases the material’s strength and dimensional stability, making its mechanical performance similar to that of BOPP (biaxially oriented polypropylene) and BOPET (biaxially oriented polyethylene terephthalate) films, which currently dominate the food packaging market and beyond.

The result is an ultra-thin film that is incredibly transparent, glossy, and much stronger than non-oriented films.

From production to application: how oriented PLA films are made

Production starts with PLA granules, which are extruded at high temperature into a thin film. For MOPLA, the film is then passed through a series of rollers that stretch it in just one direction, imparting strength and stiffness primarily along the length.

For BOPLA, the process is more complex: the film is first stretched in the machine direction and then transversely using special “stenter” frames that stretch it sideways.

Careful control of temperature, speed, and stretch ratio allows manufacturers to tailor the final properties of the film. A well-produced BOPLA film can achieve levels of transparency, gloss, and strength comparable to the best petrochemical films—while also offering the advantage of compostability.

A comparison with PP, PET, and PE: strengths and limits of oriented PLA

When it comes to packaging films, comparison with traditional materials is inevitable. Biaxially oriented PP (BOPP) is a market leader thanks to its excellent moisture barrier, low cost, and versatility.

Oriented PLA (both MOPLA and BOPLA) is positioned between these materials:

- It offers better transparency and rigidity than PE, with a very good aroma barrier, even though it doesn’t reach PET’s performance in “barrier” applications.

- Its thermal resistance is lower than that of BOPP and BOPET, although orientation improves its usable temperature range.

- The truly revolutionary aspect is compostability: at the end of its life, PLA films can be treated in industrial composting plants, thus closing the loop of the circular economy.

- PLA does not come from petroleum but from renewable crops, reducing dependence on fossil resources and the climate impact of production.

New applications and market opportunities

The production flexibility and performance of oriented PLA films are opening the way to numerous applications, many of which were unthinkable just a few years ago for a bioplastic.

In the world of food packaging, MOPLA and BOPLA are increasingly used for flowpacks, transparent pouches, bags for fresh and baked products, trays, labels, and even for printable films that can be laminated with paper or other compostable materials.

The labels sector particularly appreciates MOPLA for its directional strength, while BOPLA, thanks to its dimensional stability and gloss, is used in packaging that requires high performance and a premium appearance.

Beyond food, applications are spreading into technical sectors for blister packs, protective films, and compostable single-use products, especially where regulations encourage or mandate the use of certified compostable materials.

Recycling PLA: real opportunities and challenges

One of the most debated topics remains the end of life for PLA products. In theory, oriented PLA is completely compostable in industrial facilities, but the practical reality is still complex:

- In many cities, compostable waste collection is not well differentiated, and PLA films often end up with traditional plastics, risking contamination of recycling streams.

- Mechanical recycling of PLA is technically possible but requires dedicated supply chains and sufficient volumes, conditions not always easy to achieve at present.

- More promising, although still experimental, is chemical recycling, which allows PLA to be depolymerized back to lactic acid, enabling a true closed-loop cycle.

- The future of oriented PLA will also depend on the ability to create efficient collection and treatment systems, as well as on the spread of industrial composting plants.

Conclusions: a rapidly evolving material

Oriented PLA films, both monodirectional and biaxial, represent one of the most interesting evolutions in sustainable packaging. While they have not yet fully replaced fossil-based polymers in the most demanding applications, they have already carved out a significant space for themselves thanks to their properties and the growing environmental awareness of companies and consumers.

Ongoing research, both in materials and production processes, promises to soon overcome current limitations in thermal resistance and gas barrier properties, while improvements in recycling and composting systems will be key to achieving truly circular packaging.

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