Fabrication and Mechanical Properties of Flax/Basalt Fibers-Reinforced Polypropylene Thermoplastic Composites Hybridized at the Yarn Level

Abstract

The natural fibers- and synthetic fibers-reinforced polymer hybrid composites have the advantages of low economical costs, good mechanical properties, low hygroscopicity and environmental sustainability. In this work, the flax fibers (F), basalt fibers (B) and polypropylene long fibers (PP) were used to prepare the wrapped yarns with hybridizing on yarn level. The polypropylene was a thermoplastic synthetic resin with excellent properties and low melting point. The wrapped yarns and PP yarns were further manufactured on the unidirectional fabrics by three weaving methods, which were laminated and hot pressed to prepare the hybrid composites. The effects of weaving methods, PP content and basalt fibers content in wrapped yarns on the mechanical properties of composites were investigated. It was found that the two PP yarns in the core of the hybrid-wrapped yarns helped the composites to attain good mechanical properties. As compared to 3F2PP composites, the tensile strength and flexural strength of 1F2B2PP hybrid composites were increased to 213.2% and 32.4%, respectively. As the basalt fiber content increased, the damage degree of the F/B composites reduced and the composites showed good impact energy absorption. The impact damage modes of the all F/B composites were mainly circular pit and band-shaped failure. Furthermore, the multi-scale finite element models of the hybrid composites were established to predict and simulate the mechanical properties.