Radiation-induced Graft-polymerization and Cocrystallization of Microbial Co-polyesters

点击翻译按钮获取中文摘要

Using Burkhoderia cepacia D1and Delftia acidovorans isolated from active sawage, the copolymers poly (3-hydroxybutyrate-c0-3-hydroxyvalerate) [P (3HB-co-3HV)] and poly (3-hydroxybutyrate-co-4-hydroxyvalerate) [P (3HB-co-4HB)] were biosynthesized from mixed carbon sources of butyric acid and valeric acid (VA) or γ-butyrolactone (γ-BL), respectively. The contents of 3IIV or 4IIB component increased with increasing in concentration of VA or γ-BL.. The curve of melting points of P (3HB-co-3HV) against the 3HV contents showed an eutectic point at ca. 40% 3HV, suggesting the 3HV component was included in P (3HB) crystal. Biodegradation rate of P (3HB) and its copolymer radiation-graft-polymerized with methyl methacrylate was retarded, while those with acrylic acid was promoted. The rate of spherulites growth of P (3HB) grafted with stylene was slightly decreased, while that grafted with vinyl acetate was significantly retarded. Heat resistance and mechanical property were improved by grafting. Cocrystallization was observed P (3HB-co-3HV) at 3HV content less than 40%, while it was not observed in other range of P (3HB-co-3HV) or all range of P (3HB-co-4HB). Crystallinity of the latter decreased by copolymerization. Enzymatic degradation of single crystals of P (3HB-co-4HB) occurredl not only at crystal laterals but also at folded chain regions. The small amounts of 4HB cornponents were included in P (3HB) crystals as crystal defects. Finally, poly (L-lactic acid) and Bionolle, which were considered to be the fastest ones to commercialize, were irradiated to introduce crosslinking in order to improve thermal stability or heat-resistance at temperature range above glass transition temperatures or even above melting points.