Studies on flax-polypropylene based low-twist hybrid yarns for thermoplastic composite reinforcement

In this present study, thermally treated flax–polypropylene (PP) based hybrid yarns have been manufactured using DREF-3 spinning method for thermoplastic composite reinforcement. The effect of different process parameters such as core yarn twist level, sheath ratio and thermal treatment temperature on hybrid yarn properties has been studied thoroughly using Box–Behnken design. The DREF-3 spun hybrid yarn for composite reinforcement is optimized based on weavability performance, tensile behaviour and flexural rigidity. Further, degree of resin penetration inside DREF yarn-based unidirectional composite structures and their tensile properties are taken as parameters to judge the quality of composite. It has been observed that increase in sheath ratio, surface treatment temperature and decrease in core twist level resulted in enhancement of weavability of hybrid yarns and also in improvement in resin penetration inside composite structures.