Old Rubber Problem For Chemist.

New Zealand Graphic, Volume XL, Issue 1, 4 January 1908, Page 47

Old Rubber Problem For Chemist.

How to regenerate rubber? So far old rubber is waste rubber. The chemists do not admit the word waste to their vocabularies, but try to transform it into something useful. The great bulk of the rubber produced is of good quality, and if it went into consumption in the state of purity in which it is received by the manufacturer the average quality of the waste also would be high. But substitutes of the most varied character are added in process of manufacture. Mineral matters of many sorts sometimes make up the greater part of the weight of what is sold as india-rubber, while the rubber itself is largely replaced by substitutes, generally consisting of some form of solidified oil. The stumbling block to most inventors who have endeavoured to use rubber waste is the sulphur used in vulcanising. Part of it enters into chemical combination with the rubber, so that it is difficult to expel without injury to the quality. At present vulcanisation is a necessity, for no other process has been found to render the rubber inert to changes of temperature. Once the vulcanisation has taken place, the cut surfaces of the rubber will no longer adhere to each other, so that, the material cannot be worked into a homogeneous mass. It is probably the sulphur that is the cause of the disintegration of rubber, since crude rubber keeps for a great number of years without disintegration. Despite the poor quality of the recovered rubber, there is considerable demand for the article, especially in the United States. No less than 10,000 tons of waste rubber were imported in 1906. Waste rubber is assorted into about a dozen different grades, which vary in price according to the quality of the rubber they contain and the greater or less difficulty of extracting.