On the Influence of the Functionalization of Graphene Nanoplatelets and Glass Fiber on the Mechanical Properties of GFRP Composites

This work presents the influence of functionalised graphene nanoplatelets (f-GnPs) and functionalised glass fibers (f-fiber) on the tensile strength and the fracture toughness of the GFRP composites. The functionalization on the glass fabric and GnPs was performed by using 3-Aminopropyltriethoxysilane (APTS) as a coupling agent and confirmed by Fourier Transform Infrared (FTIR) Spectroscopy. The GnPs (non-functionalised and functionalised) with 0.1 wt% was introduced in the composites in two different ways, (1) dispersing GnPs/f-GnPs in epoxy; (2) depositing GnPs/f-GnPs on the functionalized fiber (f-fiber) surface. The mechanical properties, such as tensile strength and Mode I fracture toughness of the multi-phase composites were investigated. The longitudinal intra-laminar Mode I fracture toughness test was performed on the compact tension (CT) specimens by using the digital image correlation (DIC) technique to perform the fracture control study. The tensile fracture surface morphology of the composites was examined by Scanning Electron Microscope (SEM). The tensile strength of the composites with f-GnPs deposited on the f-Fiber outperformed the unmodified composites with 16% enhancement owing to the strong fiber/matrix interface bonding developed by f-GnPs. The composites with f-GnPs dispersed in the matrix showed an increase in the fracture toughness (K-IC) of 76% over the unmodified composites. The effects of the f-GnPs dispersed in the matrix showed good interfacial adhesion, while the composites with f-GnPs deposited on the f-Fibers showed poor fiber/matrix adhesion, as observed in the tensile fractography of the composites.

Automated summary

This study explored the effects of functionalised graphene nanoplatelets and functionalised glass fibers on the mechanical properties of GFRP composites, showing that depositing f-GnPs on f-Fibers can significantly enhance tensile strength, while dispersing f-GnPs in the matrix can improve fracture toughness.