Study of mechanical behavior of Kevlar/polypropylene hybrid yarns and their composites

In this paper, the mechanical characteristics of Kevlar multifilament-polypropylene (KV M/F-PP) hybrid yarns and its composites have been studied. The hybrid yarns have been prepared by the principle of friction spun method in a DREF-3 (Dr Ernst Fehrer A. G. the name of the inventor 1973) Machine. The system uses Kevlar-29 (poly paraphenylene terephthalamide) multifilament (KV M/F) and polypropylene (PP) of 38 mm staple length fibres as core and sheath materials, respectively. The tensile properties of selected reinforcing materials and hybrid yarns are tested before preparing the composite samples. The weight percentages of KV M/F were kept as 0%, 15%, 20%, 25% and 30% corresponding to the percentages of matrix. DREF-3 hybrid yarns are characterized by very homogeneous component distributed over the yarn cross-section. The hybrid yarn is used for thermoplastic composites in compression molding, where Kevlar multifi laments take place in core as reinforcing materials and sheath or wrapped PP fibres as matrix. The prepared composite samples have been studied using specific standards to evaluate the void volume fraction and the tensile behavior in the standard conditions. The composite having 30% of Kevlar shows the highest tensile strength with a high void percentage, however, the elongation to break is a minimum due to lower weight percentage of low elastic modulus polypropylene matrix as compare to other samples.