Abstract
Natural rubber was reinforced with various concentrations of sisal and coir fibres. Green strength measurements were carried out to determine the fibre orientation. The rubber–fibre interfacial bond was improved by a resorcinol-hexamethylene tetramine dry bonding system. The composites were vulcanized at 150°C, and the curing characteristics of the hybrid system were studied. The stress- strain behaviour, tensile strength, modulus, elongation at break, tear strength in longitudinal and transverse fibre orientations, Shore-A hardness and abrasion resistance were determined by standard ASTM procedures. The tensile strength, tear strength and tensile modulus increased with the addition of fibres up to 30 phr and then decreased at still higher fibre loadings. The hardness, density and abrasion resistance increased with the addition of fibres whereas the elongation at break decreased. The fracture surfaces of the composites were examined by scanning electron microscopy (SEM). The tensile properties were considered using parallel and Hirsch models.
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