Preparation of Polylactic Acid/Modified Natto Composite Films and Property Evaluation

Area of Science:

• Materials Science
• Polymer Chemistry
• Biomaterials Engineering

Background:

• Natto, a fermented soybean food, contains polyglutamic acid (γPGA).
• Surface modification of natural materials can impart novel properties.
• Sustainable and active packaging solutions are in high demand.

Purpose of the Study:

• To synthesize polyglutamate-coated natto (PGM-natto).
• To create and characterize polylactic acid (PLA)/PGM-natto composites.
• To evaluate the potential of these composites for active and environmentally friendly packaging.

Main Methods:

• In situ synthesis of PGM-natto using methanol and H2SO4.
• Characterization using ATR-FTIR, DSC, and TGA.
• Compounding with PLA via twin-screw extrusion and film fabrication using cast and sheet extrusion.

Main Results:

• PGM-natto was successfully synthesized and characterized.
• PLA/PGM-natto composites showed significant improvements in mechanical properties (tensile strength, Young's modulus, %E at break) at 1 wt% PGM-natto.
• Increased PGM-natto content beyond 1 wt% led to a decline in mechanical properties due to particle distribution issues.
• Enhanced surface and bulk hydrophilicity improved printability and oxygen barrier performance.

Conclusions:

• PGM-natto is an effective reinforcing agent for PLA.
• PLA/PGM-natto composites offer enhanced mechanical and barrier properties.
• These composites show promise for active and sustainable packaging applications.