Influence of Surface Functionalization of Nanofillers on Composite Failure Modes

Abstract

Surface functionalization of nanofillers, such as carbon nanotubes (CNTs), graphene nanoplatelets (GNPs), and silica nanoparticles, significantly alters their interfacial interactions with polymer matrices, impacting composite mechanical behavior and failure modes. Proper functionalization enhances dispersion, interfacial adhesion, and stress transfer, improving fracture toughness, fatigue resistance, and energy dissipation mechanisms. This study investigates the influence of various surface functionalizations on the failure behavior of polymer nanocomposites under quasi-static and dynamic loading conditions. Composites were fabricated with CNTs functionalized with carboxyl (-COOH) and amine (-NH2) groups, graphene oxide (GO) and reduced graphene oxide (rGO), and silica nanoparticles modified with silane coupling agents. Mechanical testing included tensile, compressive, interlaminar shear, Mode I and Mode II fracture toughness, and low-velocity impact tests. Fractography using SEM and TEM identified dominant failure modes such as matrix cracking, fiber–matrix debonding, nanoparticle pull-out, and delamination.