Executive Summary
Consumers, companies, and governments are increasingly favoring compostable materials over fossil-based alternatives, as waste from traditional materials has escalated significantly in recent decades. However, a key challenge with compostable materials is their inferior oxygen and moisture barrier properties compared to non-compostable options. For instance, compostable films used in flexible food packaging often lack the moisture resistance needed to maintain sufficient shelf life. Current compostable film technologies typically rely on metallization or non-fully compostable layers to achieve these properties. In response to this, researchers at Michigan State University and California Polytechnic University have developed a new process to extrude bio-sourced stereocomplex polylactic acid (sc-PLA) films without the need for masterbatches, creating compostable films with good barrier. Furthermore, the sc-PLA has been used to make a compostable laminate structure comprised of other biodegradable polymers and coatings with excellent barrier for many food applications.
Description of the Technology
The technology utilizes cast extrusion of two enantiomeric forms of PLA, specifically L-PLA (PLLA) and D-PLA (PDLA), to produce stereocomplex PLA (SC-PLA) as a monolayer film, which is then annealed as a substitute for biaxial orientation. The moisture vapor transmission rate (MVTR) at 38°C and 90% relative humidity was as low as 0.433 × 10−14 ((kg m)/(m² s Pa)), with the best samples showing a transmission rate of 180 g/(m²day) for films normalized to 25.4 µm at 37.8°C and 90% relative humidity. This performance was approximately twice as effective as films made from either L-PLA or D-PLA alone. When used as a layer in a laminate structure, the performance of the film is increased further to 10 g/m2*d MVTR and 10 cc/m2/d OTR.
Benefits
- Uses bio-sourced polymer PLA with a varied amount of d-PLA.
- Good moisture barrier and oxygen barrier
- Feasible to scale up in a short time
- Compostable
Applications
- Packaging films for food such as meat, cheese and salt snacks
- Biodegradable agricultural films
- Biodegradable thermoplastics
Patent Status
References
“Unlocking the secrets of high-water barrier stereocomplex polylactide blend extrusion films”, Green Chemistry 2024
“Composting Performance of l-Poly(lactic acid), d-Poly(lactic acid), Their Blends, and Stereocomplex PLA Films.” ACS Omega 2025
“Density and Crystallinity Correlations: Enhancing Moisture Barrier Properties in Poly(l-Lactic Acid), Poly(d-Lactic Acid), and Stereocomplex-Poly(l,d-Lactic Acid) Films.” Journal of Applied Polymer Science, 2025
“Biodegradable and Transparent Water and Oxygen Barrier Multilayer Film.” Applied Polymer Materials, 2025
Licensing Rights
Full licensing rights available
Inventors
Dr. James Macnamara, Dr. Rafael Auras, Dr. Maria Rubio, Dr. Matthew Daum, Dr. Ajay Kathuria
TECH ID
TEC2024-0074, TEC2024-0175
