The primary tree source is Hevea brasiliensis, although other trees and some shrubs are minor sources. Other sources are Africa, India, South America, and the Philippines. Rubber does not dissolve in water, alcohol or acetone. It swells and disperses in a number of organic solvents, such as toluene and benzene. Currently, accelerators have largely replaced heat to vulcanize rubber with sulfur.
Accelerators are chemicals that accomplish the same end.
They include carbamates, thiurams, and mercaptobenzothiazoles. Antioxidants, such as phenols, prevent air and ozone from causing the rubber to become brittle over time. These many constituents afford the unfortunate reality of many kinds of medical reactions. The rise in frequency is often blamed on the increased use of rubber gloves for protection against exposure to AIDS virus present in the bodily fluids of patients. Reactions fall into three groups.