Improving mode I fracture response of glass fiber-epoxy composite adhesive joints using sanding treatment and MWCNTs inclusion

Abstract

This study investigates the enhancement of fracture behavior in laminated composites using a combination of surface treatments and nanomaterial incorporation. The adherent material used is glass fiber-reinforced polymer (GFRP), and the surface treatment was applied to the GFRP surface. The adhesive used in the joints is an epoxy-based adhesive, which was reinforced with Multi-Walled Carbon Nanotubes (MWCNTs) to improve its mechanical properties. Initially, mechanical sanding techniques were explored, revealing significant improvements of 55% in fracture energy and 38% in load-bearing capacity with optimal 240-grit sanding. Subsequently, MWCNTs were introduced at varying weight percentages (0.1%, 0.3%, and 0.5%) into the adhesive. This combined approach aimed to synergistically examine the impact of surface pretreatments and nanoparticle integration on the fracture behavior of the GFRP joints. Results highlight the potential for fracture resistance and enhanced load-carrying capabilities in reinforced specimens, with maximum load and fracture energy improvements of up to 92% and 50%, respectively, compared to unreinforced specimens and those subjected solely to sanding treatments. Moreover, the shift in failure mode from adhesive failure to cohesive substrate failure was observed and is attributed to the enhanced bonding area created by the 240-grit sanding and the increased fracture resistance from the incorporation of 0.3 wt% MWCNTs. The inclusion of MWCNTs provides additional toughening mechanisms such as crack bridging and pull-out, which significantly increase the fracture energy. This comprehensive investigation underscores the intricate interplay between mechanical preparation and nanomaterial incorporation in significantly improving the performance of laminated composites.