Synergistic enhancement of mechanical, thermal, and electrical properties in Poly(3-Hydroxybutyrate-co-3-Hydroxyvalerate)/Epoxidized natural rubber/Graphene nanoplatelet (PHBV/ENR/GNP) nanocomposites for sustainable antistatic applications

Abstract Poly(hydroxybutyrate-co-valerate) (PHBV) suffers from inherent brittleness and limited processability, restricting its potential despite excellent biodegradability. In this study, PHBV was blended with natural rubber (NR) and epoxidized natural rubber (ENR), and further reinforced with graphene nanoplatelets (GNP), to develop multifunctional biodegradable nanocomposites with improved mechanical, thermal, and electrical performance. SEM analysis revealed that PHBV/NR exhibited severe phase separation and porous morphology due to polarity mismatch, resulting in a 45% reduction in tensile strength compared to neat PHBV. In contrast, PHBV/ENR blends displayed uniformly dispersed spherical domains arising from epoxy–carbonyl interactions, leading to a 30–37% increase in elongation at break while maintaining reasonable strength retention. Based on this improved compatibility, the PHBV/ENR (85/15) blend was selected as the matrix for GNP incorporation. The addition of GNP further enhanced tensile strength by up to 12% and modulus by 31%, depending on filler loading. FTIR and XRD confirmed molecular interactions and GNP-induced structural ordering, while DSC demonstrated reduced crystallinity with increasing GNP loading due to restricted chain mobility. TGA indicated improved thermal stability of the nanocomposites after GNP incorporation. SEM observations of the nanocomposites further confirmed relatively good GNP dispersion at moderate loading and the formation of stacked structures at higher filler content. Notably, GNP progressively increased electrical conductivity into the antistatic range (10 − 9 –10 − 6 S/cm) through the formation of interconnected conductive pathways within the polymer matrix. These results demonstrate a synergistic reinforcement effect, highlighting the potential of PHBV/ENR/GNP nanocomposites as sustainable materials for antistatic packaging, flexible electronics, and conductive applications utilizing a biodegradable matrix.