ABSTRACT
This chapter deals with the conventional vulcanization materials. Within broad limits any vulcanizing agent can be used in press cures. Open steam curing is used to vulcanize hand-built hose, usually made in 50-ft lengths. Rubbers like natural rubber and styrene-butadiene rubber can be vulcanized with sulfur as the only curing agent. Compared to sulfurless vulcanizing, the use of sulfur brings some general advantages. Unlike peroxides, for example, sulfur does not react very much with ingredients in the compound other than the accelerators and activators. Peroxides are rather hazardous chemicals and require more attention to safe storage and handling procedures than many other compounding ingredients. Few specific rules can be given regarding the peroxide concentrations, curing temperatures, and vulcanizing time that should be used. Customary curing temperatures are between 320 and 380°F for the majority of compounds. Some compounds present in zinc oxides can have effects on mixing or curing.
