Vulcanization is an important step in the manufacture of solid tires in which the crosslinking process occurs. In vulcanization, the materials commonly used as activators and coactivators are ZnO and stearic acid, respectively. In this research, ZnO and stearic acid were replaced with zinc stearate to improve the characteristics of vulcanized rubber. Zinc stearate was applied in four formulas with a composition of 5 to 9 phr. A formula that is often used in the rubber industry was used as a comparison, and ZnO and stearic acid of 5 phr and 2.5 phr, respectively, were applied. The rubber compound for solid tire production was developed using an open mill at a compounding temperature of 45 °C ± 5 °C. The vulcanization process of developing the rubber compound into vulcanized rubber was carried out at 150 °C for 20 min. Rubber compound test results showed that the use of zinc stearate at a ratio of 8 phr accelerated the curing time (t₉₀) between 58.3% and 69%, the scorch time (ts2) between 22.4% and 95.5%, and the torque delta (Δ_s) between 17.67 and 24.21 kg-cm. In addition, the vulcanized rubber mechanical properties test results for the compression set parameter increased between 28.6% and 57.1%. Scan results with SEM–EDS showed that using ZS could improve the homogeneous distribution of the material in the vulcanized matrix of solid tire rubber.

In its application, Ca-stearate served as a processing aid to smooth the flow of rubber in the mold and reduce the viscosity value during the printing process of rubber goods. This study aims to observe the application of ca-stearate synthesis of palm oil derivatives compared to commercial ca-stearate manufacturing rubber goods between rubber processing aid (RPA) formulas. The testing was adjusted to the industry's evaluation parameters for the rubber goods production process. The results of the Spiral Flow Test showed that the length of rubber flow with RPA was 53.14%, and the commercial RPA was 38.16% longer than without RPA. The weight of rubber samples with RPA was 54.86%, while the commercial RPA was 42.58% heavier than without RPA. As for the hardness value, the change in the value of the Compression set was 25%, 100 o C, 72hrs, Tensile Strength (tensile strength), and Elongation at Break. The rubber processing aid formulation of Ca-based palm oil derivatives excels in the 3 PHR rubber formula; 68kgf, 2.72kg/ cm 2 , 966.713kg/cm 2 , and 145.75%.