Polymer degradation into the bore of the pipe, and fuel leakage and fire may follow. The problem of ozone cracking can be prevented by adding anti-ozonants to the rubber before vulcanization. Ozone cracks were commonly seen in automobile tire sidewalls, but are now seen rarely thanks to these additives. On the other hand, the problem does recur in unprotected products such as rubber tubing and seals. The polymers are susceptible to attack by atmospheric oxygen, especially at elevated temperatures encountered during processing to shape. Many process methods such as extrusion and injection moulding involve pumping molten polymer into tools, and the high
Frasch process Frasch process The Frasch process is a method to extract sulphur from underground deposits. It is the only industrial method of recovering sulphur from elemental deposits. Most of the world's sulfur was obtained this way until the late 20th century, when sulfur recovered from petroleum and gas sources became more commonplace (see Claus process). In the Frasch process, superheated water is pumped into the sulphur deposit; the sulfur melts and is extracted. The Frasch process is able to produce high purity sulfur. The Frasch sulfur process works best on either salt domes or bedded evaporite deposits, where sulfur is found