What is Vulcanized Rubber?
Vulcanized rubber: Treatment of rubber to give it certain qualities, e.g., strength, elasticity, and resistance to solvents, and to render it impervious to moderate heat and cold. Chemically, the process involves the formation of cross-linkages between the polymer chains of the rubber’s molecules. Vulcanization is accomplished usually by a process invented by Charles Goodyear in 1839, involving combination with sulfur and heating. A method of cold vulcanization (treating rubber with a bath or vapors of a sulfur compound) was developed by Alexander Parkes in 1846. Rubber for almost all ordinary purposes is vulcanized; exceptions are rubber cement, crepe-rubber soles, and adhesive tape. Hard rubber is vulcanized rubber in which 30% to 50% of sulfur has been mixed before heating; soft rubber contains usually less than 5% of sulfur. After the sulfur and rubber (and usually an organic accelerator, e.g., an aniline compound, to shorten the time or lower the heat necessary for vulcanization)
Rubber originally came from the Indians of South and Central America. They called it caoutchouc from the word, cahuchu which meant weeping wood. This natural gum came from tree sap. Columbus introduced the gum to the western world. Once people found they could use it to rub out pencil marks, it became known as rubber. In the early 1830’s rubber products were very popular. Factories sprung up to meet demand; but the craze was short-lived. The problem was that rubber melted in hot weather, and became brittle in cold weather. Weatherproof, or vulcanized rubber, had yet to be discovered. During the course of the 1830’s many inventors searched for a way to weatherproof rubber. Charles Goodyear was one of these inventors. Bankrupt and jailed for unpaid debts, he continued his experiments, even behind bars. At one point he took up residence in a squalid tenement where his brother-in-law lectured him about his obsession, reminding him his children needed to eat, reasserting that rubber was dea
In order to give rubber added durability and a smooth appearance it must undergo a chemical process called “vulcanization” whereby sulfur and other curative substances are added to the rubber and treated under extremely high temperatures to create strong, polymer bonds at the molecular level. Although not present in the finished product, animal fats are typically used as lubricants in the vulcanization process. For this reason, Vegansoles.com regards shoes containing vulcanized rubber as non-vegan.
