The Influence of Palm Oil-Based Zinc Stearate Application on Vulcanized Rubber: Analyzing Hardness, Tensile Strength, and Elongation at Break for Hand Grip Formulation Development

Vulcanization of rubber compounds is a crucial step in the process of developing natural rubber end products. Selected components are then used to formulate a rubber compound, which is further treated to create vulcanized rubber. In this study, a palm oil-based zinc stearate compound (ZS) developed by the National Research and Innovation Agency (BRIN) was used as a replacement for ZnO and stearic acid, which were previously used as activator and co-activator in the process of vulcanization. The goal of this study was to create a compound made of rubber formulation for use in the hand grip. The zinc stearate applied in this study ranged from 4 to 6 phr. To examine the effect of applying zinc stearate to vulcanized rubber, three primary parameters - tensile strength, hardness, and elongation at break of the vulcanized rubber - were evaluated. The results of the tests revealed that adding zinc stearate at a loading rate of 4 phr gave the hardness value of 27 Shore A, the tensile strength of 19 MPa, and the elongation at break by 590%. With this mechanical characteristic, the formula was identified as the optimal choice for achieving a robust and deformation-resistant hand grip while ensuring user comfort.