Synthesis of polyvinyl alcohol/modified starch-based biodegradable nanocomposite films reinforced with starch nanocrystals for packaging applications

In the present work, corn starch was grafted with oleic acid in the presence of redox initiators. Starch nanocrystals (SNCs) were synthesized using acid hydrolysis method and nanocomposite films were prepared by incorporation of SNCs into polyvinyl alcohol/starch (PVA/S) and PVA/grafted starch (PVA/GS) matrix, separately. It was observed that SNCs exhibited a platelet-like shape and in the size range of 200 nm. The increased crystallinity of SNCs indicated the removal of the amorphous and waxy region after acid hydrolysis of starch. Scanning electron micrographs of nanocomposite films showed good dispersion of SNCs within the PVA/GS matrix compared to the PVA/S matrix. The tensile strength of the nanocomposite films increased significantly with the reinforcement of SNCs into PVA/S matrix. Water uptake (%) of PVA/GS nanocomposite film decreased by 38.25% compared to the PVA/S nanocomposite film. Reinforcement of SNCs with PVA/S matrix improved the biodegradability of the films and was higher than PVA/S film. PVA/S nanocomposite film showed 32.4% weight loss after 120 days of soil burial degradation test. Thus, the obtained nanocomposite films can provide a potential alternative to the synthetic and nondegradable packaging films used worldwide.