Cure Terms Glossary

Retarder

A retarder may be required in accelerated-sulphur vulcanisation when the viscosity of the mix is such that the temperatures reached in processing may cause premature vulcanisation (scorch). This could well be the case when highly-reinforcing fillers are used. Ideally a retarder should merely delay the onset of cure (rather than slow down the cure). Species of the type R—S—N<, where R is a grouping which does not contain the proton acceptor sites of a vulcanisation accelerator, can operate in this way. Such an example is N-cyclohexylthiophthalimide.