Enzymatically degradable and flexible bio-nanocomposites derived from PHBV and PBAT blend: assessing thermal, morphological, mechanical, and biodegradation properties

Abstract

In order to enhance flexibility of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV), blending was carried out with poly(butylene adipate-co-terephthalate) (PBAT) to generate PHBV/PBAT blend (50/50 wt.%/wt.%) using conventionally accepted melt blending process. Two different types of fillers were used to generate nanocomposites, graphene nanosheets (synthetic filler), and vermiculite (natural filler), via melt blending. Thermal, mechanical, and biodegradation properties were assessed in neat polymers, blend, and nanocomposites with different fillers. Effect of blending and different filler loadings on mechanical properties was analyzed systematically where blending of PHBV with PBAT manifested dramatic enhancement of strain at break whereas tensile modulus was well preserved. Nanocomposites manifested significant enhancement in tensile modulus along with higher strain at break as compared to neat PHBV. Biodegradation rate of PHBV was observed to be enhanced by blending with PBAT. In case of nanocomposites, graphene led to suppression of degradation rate whereas vermiculite resulted in faster degradation over neat blends. In context, composites with 10 wt.% vermiculite showed 108 and 1500 % higher degradation in lipase and phosphate buffer saline environment after 8 days, respectively, over neat PHBV. In general, composites with vermiculite exhibited excellent set of properties like tensile modulus, flexibility, and biodegradation. These bio-nanocomposites represent promising candidates for structural applications where biodegradation is a prime requirement, thus leading to an eco-friendly environment.