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 cur e characteristics and physicomechanical properties of natural rubber ( NR) modified with phosphorylated cashew nut shell liquid (PCNSL) in va rious proportions has been studied. Prominent cure retardation has bee n observed with progressive increase in concentration of PCNSL from 0 to 20 phr. The softening effect of PCNSL on the vulcanizate has been d isplayed by the linear decrease in hardness and tensile modulus and th e increase in elongation at break with the increase in concentration o f PCNSL. The results on the tensile and tear strengths of the vulcaniz ates showed that the reinforcing effect of the fillers were maximized at concentrations of PCNSL ranging from 5 to 10 phr. Also, the PCNSL-m odified NR vulcanizates showed improved resistance to thermo-oxidative ageing and decomposition, especially at the higher concentration of 2 0 phr. (C) 1998 John Wiley & Sons, Inc.