Thermo‐Mechanical Behavior and Shape Memory Performance of Graphene Nanoplatelets‐Reinforced Epoxy Nanocomposites

Abstract

ABSTRACT Epoxy‐based shape memory polymers (SMPs) are widely used in aerospace and structural applications. However, their limited toughness and recovery behavior restrict their broader application and their performance over repeated actuations is less understood. This study provides a comprehensive analysis of the mechanical and viscoelastic properties of graphene nanoplatelets (GNPs) dispersed epoxy nanocomposites, along with an investigation into the short‐term (five‐cycle) multi‐cycle shape memory behavior. GNP were dispersed into an epoxy matrix via probe ultrasonication to enhance shape memory behavior and mechanical performance. At 0.2 vol.% GNP loading, tensile strength, flexural strength, fracture toughness, and fracture energy increased by 21.8%, 24.3%, 33.8%, and 41.3%, respectively, relative to pristine epoxy. Young's modulus and flexural modulus exhibited improvements of 18.5% and 22.8%. Dynamic mechanical analysis confirmed superior stiffness, energy dissipation, and viscoelastic stability with the incorporation of GNP, attributed to restricted chain mobility and efficient stress transfer. Fractographic analysis revealed crack deflection and pinning as the primary toughening mechanisms. Shape memory testing indicated that pristine epoxy achieved the highest fixity ratio (98.11%). At the same time, nanocomposites exhibited marginal reductions in fixity but accelerated recovery response due to improved thermal conductivity and stored elastic energy. A baseline assessment of short‐term (five‐cycle) shape memory response showed all compositions demonstrated complete (≈100%) recovery across five programming cycles, with minor declines in fixity and slight increases in recovery time at higher GNP concentrations. The results establish GNP‐reinforced epoxy SMPs as durable, high‐performance materials with enhanced actuation stability under repeated thermal cycling.