Premature Curing
Premature Curing
(also scorching), an irreversible reduction in the plasticity of rubber stock, which can occur during manufacturing, processing (for example, during calendering), or storage. Premature curing is caused chiefly by the interaction of raw rubber with vulcanizing agents in the stages of the production process that precede actual vulcanization. As a result, it is difficult, and sometimes impossible, to process the stock into a product. Retarders, or antiscorching agents, are introduced into the rubber stock to prevent premature curing. Phthalic anhydride and N-cyclohexylthiophthalimide are examples of retarders.