Mechanics of reinforcement in a hybrid graphene and continuous glass fibre reinforced thermoplastic

Hybrid nanomaterial-fibre-reinforced polymer composites show considerable promise but are often limited by the poor dispersion of the nanofillers, with filtering by the fibre weave being a common issue. Herein, a hybrid continuous glass fibre reinforced polymer (GFRP) was prepared based upon a polypropylene matrix, woven E-glass fibre (GF) and graphene nanoplatelets (GNP). The GNP flakes were melt-mixed with a polypropylene-graft-maleic anhydride (PP-MAH) compatibiliser and then melt-coated onto the GF mats, followed by layer-by-layer assembly using polypropylene films and coated fibre mats in a hot press. It was found that the stiffness and strength of the GFRP were increased by up to ∼3 GPa (25%) and ∼120 MPa (95%), respectively, by the addition of up to only ∼ 1.7 vol% of the GNP, to the composite. The experimental results enable us to extend our previous theory of mechanics of reinforcement by 2D materials to FRP. In-situ Raman band shift measurements on the flakes close to the glass fibres under strain found that the effective modulus of the flake is ∼130 GPa, indicating that a higher reinforcing efficiency of graphene was obtained in the FRP than in neat polymers due to improved local reinforcement effect of the matrix in the FRP.