Stearic acid plays several pivotal roles in the processing and production of rubber. Here are its primary functions:
Sulfur vulcanization activator: Serving as a common sulfur vulcanization activator for natural rubber, synthetic rubber, and latex, stearic acid promotes the vulcanization process, enhancing the degree of cross-linking and stability of the products.
Softener and plasticizer: It increases the softness and plasticity of rubber, improving processing properties, making rubber easier to shape and process while also boosting elasticity and flex resistance.
External lubricant: Used as a lubricant, stearic acid reduces friction during rubber processing, facilitating mold release and enhancing the surface quality and manufacturing efficiency of the products.
Promotes dispersion of fillers: It aids in the uniform dispersion of fillers such as carbon black, silica, and zinc oxide within the rubber matrix, crucial for achieving good physical and mechanical properties.
Reaction with zinc oxide or alkaline accelerators: Stearic acid reacts with substances like zinc oxide to form zinc soaps, which dissolve better in rubber and more effectively function as sulfur vulcanization assistants, accelerating the curing process and improving vulcanization efficiency.
Release agent: In rubber product manufacturing, stearic acid facilitates easy release of the product from molds, minimizing damage and ensuring the integrity and smooth surface finish of the products.
Although added in relatively small proportions (typically 0.5 to 3 parts per hundred parts of rubber), stearic acid significantly impacts both the performance and processing of rubber, making it an indispensable auxiliary material in rubber production.
