Effect of Phenol-CNSL Formaldehyde Copolymer on Thermal Ageing of NBR

Abstract

Cashew nut shell liquid (CNSL) is a cheap agro-by-product and renewable resource which consists mainly of substituted phenols. A CNSL based resin was used in this study to modify the aging properties of butadiene-acrylonitrile rubber (NBR). The resin was a copolymer obtained by condensing a mixture of phenol and CNSL with hexamethylene tetramine. The effect of the resin on the ageing of NBR vulcanizates was studied by following changes in tensile strength, elongation at break, modulus and tear strength. Resins with different phenol/formaldehyde ratios and CNSL/phenol ratios were incorporated into NBR and the physical properties determined. Comparison of the properties of the aged material containing the CNSL resin with those of specimens not containing the resin show improved ageing characteristics with respect to tensile strength, modulus and tear strength.