Sulfur is the traditional vulcanizing agent used with natural rubber. Silicones use moisture, acetic acid and other compounds as curing agents. ASTM C1184 - Standard specification for structural ...
natural rubber is a polymer of isoprene, and is prepared as sheets and then dried. Synthetic rubbers or elastomers can be based on a variety of systems such as silicone, polyurethane or neoprene.