Improved compatibilization and shape memory properties of poly (3-hydroxybutyrate-co-3-hydroxyvalerate)/poly(ethylene-co-vinyl acetate) blends by incorporation of modified reduced graphene oxide

Reduced graphene oxide modified with vinyl laurate (rGO-VL) was incorporated to extruded blends of poly(3-hydroxybutyrate co-3-hydroxyvalerate) (PHBV) and poly(ethylene-co-vinyl acetate) (EVA) at different compositions. X-ray diffraction analyses showed decrease in crystallinity for the PHBV/EVA/rGO-VL hybrids in relation to the neat blends. Scanning electron microscopy images and dynamic mechanical analyses (DMA) indicated that well-dispersed rGO-VL sheets contributed to the blends compatibilization. DMA results revealed improved flexibility as the rGO-VL content was increased. Differential scanning calorimetry showed that EVA and rGO-VL acted synergistically to reduce PHBV crystal size. Tensile tests showed increased flexibility for PHBV/EVA/rGO-VL hybrids. Cyclic shape memory tests and folding-unfolding shape recovery tests revealed enhanced shape memory properties. For the PHBV/EVA blends at 50:50 and 25:75 compositions, the recovery rate (R-I) values were (83.1 +/- 7.4)% and (70.3 +/- 6.2)%, respectively. With the addition of rGO-VL at 1.0 mass%, R-I values higher than 97.0% and a shorter recovery time of similar to (3.8 +/- 1.7) s were achieved.