Synthesis and biodegradation of polymer blends of poly(3-hydroxybutyrate) and natural rubber

Abstract

Microbial polyhydroxyalkanoates (PHAs) as an ideal choice of biomaterial for specific applications. In this study, PHA was synthesized and purified from Pseudomonas mendocina PSU. These obtained PHA was then determined its monomer composition and found that 3-hydroxybutyrate (3HB) was a major component, in addition, the molecular weight were also investigated. The average Mw was 8.39 ×104 when grown in MSM supplemented with glycerol whereas the melting temperature was 172 °C. To improve mechanical and biodegradation properties of PHB, blending with suitable well defined polymers such as natural rubbers (NR) has been performed by blending poly(3-hydroxybutyrate) [(PHB)] with and epoxidized natural rubber (ENR) using two different blending methods e.g. solvent blending and melting blending in a ratio of PHB to ENR of 70:30. The polymer blends were further investigated their biodegradation by soil burial test and rubber-degrading consortium. The results clearly showed that in soil burial test, the most rapid biodegradation was PHB from P. mendocina PSU which reached to 34.10%weight loss whereas the biodegradation of polymers by rubber-degrading bacteria, interestingly the highest percentages of weight loss about 13% was obtained in PHB-ENR blend films from melt blending followed by PHB-ENR blend films from solvent blending, NR, PHB from P. mendocina PSU and ENR, respectively. In addition, the physical changes in all tested samples were observed.