The Basic Rubber Compound

The rubber compound was first developed by Goodyear and Hancock and it continues to develop as new materials and new variations on old ones appear in the marketplace. The compound we see everyday as rubber, such as in a tire or pencil eraser, is a mixture of a number of different ingredients. It starts with the raw gum elastomer, supplied by the plantation owner as NR, or by the petrochemical complex converting petroleum products such as ethylene, propylene and butadiene into 'raw' bales or chips of rubbery polymers such as EPDM, BR, SBR, NBR or CR. It is shipped to the rubber processor who blends it with various ingredients. The raw gum elastomer itself has very limited use, although adhesives provide one example. Most are mechanically weak and subject to significant swelling in liquids, and will not retain their shape after molding. Many of its other properties could also benefit from enhancement. It is at this point that the rubber compounder takes over, and all of his art and science is dedicated to modifying the raw gum elastomer, changing it into a more useful material.