Physicomechanical properties of filled natural rubber vulcanizates modified with phosphorylated cashew nut shell liquid

Effect of fillers like carbon black, silica, and china clay on the cure characteristics and physicomechanical properties of natural rubber (NR) modified with phosphorylated cashew nut shell liquid (PCNSL) in various proportions has been studied. Prominent cure retardation has been observed with progressive increase in concentration of PCNSL from 0 to 20 phr. The softening effect of PCNSL on the vulcanizate has been displayed by the linear decrease in hardness and tensile modulus and the increase in elongation at break with the increase in concentration of PCNSL. The results on the tensile and tear strengths of the vulcanizates showed that the reinforcing effect of the fillers were maximized at concentrations of PCNSL ranging from 5 to 10 phr. Also, the PCNSL-modified NR vulcanizates showed improved resistance to thermo-oxidative ageing and decomposition, especially at the higher concentration of 20 phr. (C) 1998 John Wiley & Sons, Inc.