Sulfur vulcanization sulfur is not miscible in the polymer prior to vulcanization and attention is paid to prevent sulfur bloom, where it migrates to the surface of the article. Accelerators act much like catalysts allowing vulcanisation to be performed cooler yet faster and with a more efficient use of sulfur. They achieve this by reacting with and breaking the sulfur ring to form a reactive intermediate, referred to as a sulfurating agent. This in turn reacts with cure sites in the rubber to bring about vulcanization. There are two major classes of vulcanization accelerators: primary accelerators and secondary accelerators (also known as
Rubber elasticity Joule published the first careful measurements of the temperature increase accompanying extension, confirming the theoretical predictions of Lord Kelvin. It was not until 1838 that the American inventor Charles Goodyear found that its properties could be immensely improved by adding a few percent sulphur. The short sulfur chains produced chemical cross-links. Before it is cross-linked, the liquid natural rubber consists of very long linear chains, containing thousands of isoprene backbone units, connected head-to-tail. Every chain follows a random path through the liquid and is in contact with thousands of other nearby chains. When heated, a cross-linker molecule (such as sulfur