Utilizing sulfur and zinc oxide to improve impact in hard rubber recipe designs

The current work represents a practical study with the aim of getting the best design for hard rubber recipes by controlling materials that increase this property. Rubber recipes were prepared consisting of several materials, such as natural rubber, zinc oxide, and stearic acid, in addition to the accelerator and vulcanizing agent sulfur, which was added in multiple proportions 10, 20, 30 parts per hundred rubbers (PPHR). Also, recipes were prepared for the same previous ingredients with an increased percentage of Zinc oxide to 150 PPHR to demonstrate the effect of this material on the hardness property. Some laboratory tests were conducted to investigate the mechanical behavior of these recipes, such as hardness, tension, and Rebound (resilience) tests. The recipe with sulfur 30 pphr gave an acceptable indication in hardness and tensile test with values 98 IRHD and 35 MPa respectively. The same recipe in the rebound test was not the best but was an acceptable result, while the recipe with sulfur 10 pphr was the best in resilience test results (25%). Other rubber recipes with zinc oxide at 150 PPHR gave acceptable results especially in recipes with sulfur at 30 PPHR. Two forms of the composite plate covered with a hard rubber recipe may result in an external bonding process of individual plates and a vulcanized plate with a hard rubber recipe in a thermal press. The final hard rubber recipes may be used in other applications as an alternative material to withstand various stresses with specific properties.