Preparation, characterization and biodegradation of blend films of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) with natural biopolymers

Blending of biodegradable poly(3-hydroxybutyrate-co-3-hydroxyvalerate) P(3HB-co-3HV) with natural polymer is one of alternative routes to improve the mechanical properties and reduce the cost of raw materials. Such blending is interesting to be implemented in packaging industry due to the low-cost materials, sustainable and eco-friendly. Therefore, in this study, P(3HB-co-6%3HV) copolymers synthesized by Cupriavidus malaysiensis USMAA2-4 were blended with different ratios of starch, cellulose or alginate through solvent casting technique. Hydrophilicity analysis revealed the density, water-absorption capacity and solubility of blend films increased proportionally with the increasing ratio of natural polymers. The degradation of the blend films was investigated in soil and lake. The highest percentage of degradation in the soil and lake were observed on the blend films containing starch and alginate, respectively. Meanwhile, blending of P(3HB-co-6%3HV) with cellulose has shown the lowest percentage of degradation on both locations. The blend films with 50:50 wt:wt% ratio of P(3HB-co-6%3HV): natural polymer from both locations was used for isolation of microbial degraders of poly(3-hydroxybutyrate) P(3HB), starch, cellulose or alginate. The PHAs degraders were identified from genus Cupriavidus, Acidovorax, Variovora, Streptomyces and Ideonella and two starch degraders were identified from genus Moraxella and Alcaligenes.