Renewable Compatibilizing Agent for Silica Reinforced Natural Rubber

The main problem in utilizing silica as an alternative reinforcing filler for natural rubber (NR) compounds is a weak rubber-filler interaction and poor filler distribution due to their incompatibility feature. The particles of silica have a strong tendency to filler interactions which leads to form silica agglomeration. To solve this drawback, this work has utilized ethanolamine-modified palm stearin (EMPS) as a renewable compatibilizer agent to improve NR-silica compatibility. The EMPS was prepared by a typical chemical reaction between ethanolamine and refined bleach-deodorized palm stearin (a byproduct of cooking oil production) on a laboratory scale. The influence of the EMPS on the improvement of rubber-filler interaction was investigated by studying the processing characteristics and the tensile properties of silica-reinforced NR compound (silica content was fixed at 30 phr). Compared to the silica-reinforced NR with no EMPS, it was found that EMPS caused a greater coefficient of vulcanization, tensile strength, and reinforcement effect for the silica-reinforced NR. It was due to an active reaction between silanol groups of silica with EMPS which increased the NR-silica compatibility, and the Fourier Transform Infra-Red (FTIR) analysis has confirmed the typical reaction.