ABSTRACT
Accelerator development slowed in the early 1930s, but the use of synthetic rubber and fine particle furnace black in the following decade required not only a strong accelerator but one that did not cause precure at the higher mixing temperatures involved. Since the time of Oenslager, accelerator development has concentrated on nitrogen- and sulfur-containing organic compounds. Although many accelerators are single organic chemical compounds, density ranges are often quoted by supplier. The ideal accelerator would be inexpensive and nontoxic, and wouldn't stain, discolor, or bloom. By far the most popular accelerators are the thiazoles and derivatives of the thiazoles, the sulfenamides. The various sulfenamides reflect in their scorch times and cure rates differences in the amines used in their manufacture. Dithiocarbamates, the metal salts and amine salts of dithiocarbamic acids, are called ultra-accelerators because of their quick curing characteristics.
