Biodegradable Biocomposites of Isosorbide-Plasticized Corn Starch Reinforced With Green Graphene: Enhanced Properties for Sustainable Applications

Abstract

[Abstract] New biocomposites of corn starch plasticized with isosorbide and filled with two types of “green” graphene with different oxygen content, 1% (G99) and 8% (G92), were processed by melt blending. The effects of the plasticizer nature, compared to the conventional glycerol, as well as the type and amount of graphene filler, were studied regarding the material properties. Morphology, crystallinity, and thermal, optical, and dynamic mechanical properties of the materials were analyzed, as well as their resistance to water absorption and soil burial biodegradation. Using isosorbide as a plasticizer instead of glycerol prevented starch retrogradation and produced materials with improved thermal stability, stiffness, glass transition temperature, UV–visible absorbance, biodegradation rate, and resistance to water absorption. The addition of green graphene to neat thermoplastic starch led to biocomposites with enhanced crystallinity, thermal stability, UV–visible blocking capacity, and resistance to water absorption. G92 formed stronger interactions with the starch matrix, leading to better dispersed biocomposites with higher stiffness and glass transition temperatures. Biocomposites of corn starch using isosorbide as a plasticizer and filled with low amounts of G99 (1 wt.%) or G92 (1 wt.% and 3 wt.%) showed suitable properties to be a biodegradable alternative to conventional plastics for applications such as packaging.