Biodegradable Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) and Renewable Biomass based Composites and Marine Degradation Behaviour

This thesis involves an investigation on developing biodegradable poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) based blends, and biocomposites. PHBV is derived from various agricultural carbon sources and was extruded with plasticized cellulose acetate (pCA), to develop a sustainable and biodegradable PHBV/pCA blend. PHBV/pCA blends were found to be immiscible and had reduced mechanical performance and flexibility compared to the individual components. Miscanthus fibre and distillers dried grains with solubles (DDGS) biocomposites of PHBV were developed to ascertain the effect on marine biodegradability. Under ASTM D7991-15, PHBV/Misc (75/25) and PHBV/DDGS (75/25) biocomposites increased the biodegradation rate of PHBV by 24 and 40% respectively. Marine biodegradation of PHBV/DDGS (75/25) composite exceeded cellulose and is 100% marine biodegradable in 260 days, attributed to the presence of cellulosic material and protein promoting microbial growth in DDGS. PHBV/Misc (85/15) and (75/25) had increased tensile/flexural moduli by 55 and 100%, and impact strength of 100%, relative to PHBV.