Study on mechanical and thermomechanical properties of flax/glass fiber hybrid-reinforced epoxy composites

A hybrid fiber-reinforced plastic (HFRP) composite is defined as a composite material that is reinforced by two or more continuous fiber materials in the same resin matrix. This article used the hand layup method to prepare epoxy-based flax and glass HFRP composites. Under the same fiber hybrid ratio, the interlayer and sandwich hybrid lamination methods were used for mechanical properties testing of the composite. The tensile and bending properties of the HFRP composites were obtained by tensile and three-point bending tests, and the cross-sectional morphology of the material was observed by a scanning electron microscopy. The thermomechanical properties of the HFRP composite were analyzed by the dynamic mechanical thermomechanical analysis (DMTA). The results showed that the effect of the different layup methods on the tensile properties of the HFRP composite material was less than the effect of the bending properties, and the bending properties showed a significant positive effect for the hybrid composites. When the glass fiber sheet was used as the core layer and the flax fiber sheet was used as the surface layer, the hybrid composites had improved bending properties, and their bending strength and flexural modulus were approximately 3.22 times and 3.81 times that of flax FRP composites, respectively. The storage modulus and glass transition temperature of the HFRP composites were higher than those of flax FRP composites as they increased by 84.1% and 8.01 degrees C, respectively.