Compostable Multilayer Films with Tailored Gas Barrier and Biodegradation

Area of Science:

• Materials Science
• Polymer Chemistry
• Sustainable Materials

Background:

• Poly(lactic acid) [PLA] and thermoplastic cassava starch [TPCS] are biodegradable polymers with potential for sustainable packaging.
• Developing effective blends and multilayer structures is crucial for enhancing their functional properties.

Purpose of the Study:

• To investigate the barrier and biodegradation performance of reactive blends of PLA and TPCS.
• To evaluate the impact of plasticizers (glycerol and polyethylene glycol) on the properties of PLA-g-TPCS multilayer films.
• To assess the potential of these films for sustainable packaging applications.

Main Methods:

• Reactive melt mixing of PLA and TPCS using twin-screw extrusion.
• Preparation of multilayer films via cast coextrusion.
• Characterization of structural, mechanical, thermal, optical, barrier, and surface properties.
• Biodegradation assessment using a respirometer system under thermophilic composting conditions.

Main Results:

• Fourier transform infrared spectroscopy confirmed successful grafting of PLA and TPCS.
• Reactive blending reduced tensile strength and modulus but increased elongation at break.
• Multilayer structures significantly improved mechanical properties compared to monolayers.
• Glycerol-plasticized TPCS reduced oxygen permeability by 50%, while both plasticizers increased water vapor transmission.
• Biodegradation was accelerated by TPCS but moderated by PLA outer layers in multilayer films.

Conclusions:

• PLA-g-TPCS multilayer films exhibit a promising combination of composability and functional performance.
• Plasticizer choice significantly influences film properties and biodegradation rates.
• These materials offer a viable alternative for sustainable packaging, potentially suitable for industrial and home composting.