3.1 Stearic acid is important in the rubber vulcanization process. It is believed that the stearic acid reacts with zinc-oxide or other metallic oxides, during vulcanization, to form a rubber soluble salt or soap, that reacts with the accelerator enabling it to exert its full effect.
3.2 Stearic acid of commerce is generally a mixture of palmitic, stearic, and oleic acids usually derived from tallow base stock but can be derived from other fats and oils of animal or vegetable origins.