31/05/2011

Vulcanisation

The first indigenous users of rubber did not know the vulcanisation process. They made an elastic, rubber-like material from plastic latex with the help of tree and plant sap. Rubber as we know it today still had to be invented, however: this was done in 1839, when Goodyear and Hancock – independently of each other – developed a chemical / technical process by which the plastic rubber substance can be transformed into elastic rubber.

In the vulcanisation process, a rubber blend consisting of raw rubber, sulphur or substances that provide sulphur like disulphur dichloride (S2Cl2), catalysts (to increase the reaction speed) and fillers is heated up. The long-chain rubber molecules are cross-linked by sulphur bridges in this process. The plastic properties of the rubber / rubber blend are lost as a result and the material is transformed from a plastic to an elastic state by the vulcanisation process. Compared with the original product, the rubber manufactured in this process has permanently elastic properties, returns to its original position following mechanical strain and displays higher tear resistance, better stretch properties and greater resistance to ageing and weathering.