Synthesis of new vulcanizing agent from cashew nut shell liquid

Abstract

Cardanol polysulfide (CPS)is a sulfur donor type vulcanizing agent which was obtained from the reaction of decarboxylated cashew nut shell liquid and elemental sulfur at various temperature and reaction time. The appropriate conditions for the preparation of CPS were carried out at 140 ํC without solvent for 3 hrs and an excess elemental sulfur was used to give 30%wt of sulfur content. The CPS was mixed with natural rubber and common additives by two-roll mill using CPS in place of sulfur content by controlling total sulfur content and combining CPS with constant sulfur content. The vulcanization characteristics and mechanical properties of rubber compounds were studied. It was observed that the optimum cure time of CPS containing rubbers was reduced and most of the mechanical properties of CPS containing rubber compounds were improved. Accelerated aging test was investigated and the results were compared to unaged specimens. It was observed that theCPS containing rubber have lower reversion. This work shows that the use of CPS as vulcanizing agent improved basic mechanical properties and reduced the reversion of rubber compounds.