Composite properties and biodegradation of biologically recovered P(3HB-co-3HHx) reinforced with short kenaf fibers

A compression-molded green composite material comprising of bacterially synthesized poly(3hydroxybutyrate-co-3-hydroxyhexanoate) [P(3HB-co-3HHx)] and short kenaf fibers (KF) was prepared in the present study. Accordingly, P(3HB-co-3HHx) was produced by the Cupriavidus necator Re2058/pCB113 using the palm oil as the sole carbon source, while the polyhydroxyalkanoate (PHA) copolymer with similar to 99% purity was recovered from the bacterial cells using a newly reported solvent-free biological recovery method. Experimental results showed that P(3HB-co-3HHx) containing 30 wt % KF possessed the highest flexural strength and similar or better comparable mechanical performance compared to that of the low density polyethylene (LDPE), LDPE/KF composites and high density polyethylene (HDPE). Water absorption and soil burial tests were also performed to evaluate the durability of the P(3HB-co-3HHx)/KF composites. As compared to that of the pristine P(3HB-co-3HHx), it was determined that P(3HB-co-3HHx)/KF composites demonstrated higher water absorption percentage and showed higher percentage of weight loss during the soil degradation study. Burkholderia sp., Streptomyces sp., Amyco-latopsis sp. and Streptacidiphilus sp. that involved in the biodegradation of P(3HB-co-3HHx)/KF composites during the soil degradation study were successfully isolated and characterized. These species had the capability to degrade the composite material in vitro. (C) 2017 Elsevier Ltd. All rights reserved.