Poly(Lactic Acid) Stereocomplex Cast Films With Microwave Resistant Properties by Cellulose From Hemp Biomass Composites

ABSTRACT Biodegradable food packaging has attracted vast interest in this century, though achieving microwave resistance has remained challenging due to degradation and heating issues. Due to these limitations, poly(lactic acid) or PLA, the most widely recognized biodegradable plastic, has also proven unsuitable for such applications. Thus, stereocomplexation (Sc) between PLA and its enantiomer, poly( d ‐lactic acid) (PDLA), was employed to enhance crystal formation, improving crystallinity as well as mechanical and thermal properties. For the microwave irradiation impediment, cellulose synthesized from hemp biomass (CHB), a by‐product from an industrial process, was added to the polymer matrix at loadings of 1, 3, 5, and 7 phr to mitigate the material's limitations. The chemical structure of CHB was characterized using Fourier transform infrared (FTIR) spectroscopy. Sc‐PLA/CHB composites were prepared using the solvent casting method. The films improved the mechanical strength and Young's modulus. Finally, microwave heating tests were conducted to evaluate their practical application performance. The results demonstrated that CHB exhibits a smaller particle size, higher purity, and enhanced crystallinity. Sc‐PLA/PDLA/CHB composites significantly improved mechanical strength, heat resistance, light‐blocking capability, and microwave resistance. These findings highlight the potential of this high‐performance degradable polymer for sustainable microwave food packaging applications.