Characterization and Degradation of Polyhydroxyalkanoates (PHA), Polylactides (PLA) and PHA-PLA Blends

Abstract Biodegradable biopolymers such as polyhydroxyalkanoates (PHA) and polylactide (PLA) have wide range of applications in almost all sectors. Degradation of these polymers, however efficient, still creates a paradox with green chemistry principles. Blending of these polymers can potentially decrease plastic pollution due to their increased biodegradability. During this study, PHAwas produced using bacterial strains DL3; Bacillus subtilis (MT043898), PWA; Bacillus subtilis (MH142143), PWC; Pseudomonas aeruginosa (MH142144), PWF; Bacillus tequilensis (MH142145) and PWG; Bacillus safensis (MH142146). Corn-based PLA was produced chemically and physically blendedwith PHA (PHA-PLA blends). During molecular studies, PHA, PLA and PHA-PLA blendswere characterized via FT-IR analysis, SEM, and light microscopy indicating successful blending of PHA-PLA samples. FTIR results indicated PHA produced by strain PWF and mixed culture wasmcl-PHA. Degradation of polymers and copolymer blends was studied by bacteria for 12 weeks and in different environmental systems i.e. in soil, water, air, and heat for 20 weeks. Degradation analysis indicated highest degradation of PLA, followed by PHA-PLA blends. Among these systems, degradation was favored in soil (80%), followed by water (78%) and air (78%). Least degradation (76%) was observed on heat exposure. Sample degradation observed using light microscope and SEM showed fungal and bacterial colonization amidst cracks, crevices, bumps, and fractures after 20 weeks. Understanding the role of ambient microbial population during degradation and its impact on natural soil environment can be the focus of future studies.