the act or process of treating crude rubber, synthetic rubber, or other plastic rubberlike material with a chemical (as sulfur or a compound of sulfur) to decrease its plasticity, tackiness, and sensitivity to heat and cold and to give it useful properties (as elasticity, strength and stability)
"Conversion of natural or synthetic rubber" means any process of mixing, crushing, blending, calendering, extruding and vulcanization of natural or synthetic rubber and additionally processes for the processing of natural or synthetic rubber to derive an end product.