Rubber accelerators are rubber vulcanization accelerators. Rubber vulcanization primarily uses sulfur, but the reaction between sulfur and rubber is very slow; therefore, vulcanization accelerators were developed. Adding accelerators to rubber compounds activates the vulcanizing agent, thereby accelerating the cross-linking reaction between the vulcanizing agent and rubber molecules, achieving the effect of shortening vulcanization time and lowering vulcanization temperature. The main vulcanization accelerators used are classified by chemical structure into sulfenamides, thiazoles, thiurams, and some guanidines, thioureas, and dithiocarbamates. Among them, sulfenamides have good overall performance and are widely used.
Rubber accelerators are post-treatment accelerators for natural rubber, butadiene rubber, isoprene rubber, styrene-butadiene rubber, and reclaimed rubber. They are commonly used in the manufacture of cables, rubberized sheets, rubber shoes, inner tubes, and brightly colored products, and are especially suitable for rubber compounds containing strong alkalinity and carbon black. They operate at low temperatures, have strong scorch resistance, fast vulcanization speed, high tensile strength, and can increase the proportion of synthetic rubber used. It is mainly used in the manufacture of tires, rubber shoes, rubber hoses, rubber belts, and cables.
The vulcanization mechanism of rubber remains a subject of debate. This is because the production process of rubber products involves insoluble natural rubber samples and numerous simultaneous reactions, making it difficult to study the vulcanization of rubber molecules into a complex polymer network. Early proposed rubber vulcanization mechanisms can be broadly categorized into two types: free radical mechanisms and ionic mechanisms.
