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
Union Sulphur Company original patents thus expired in 1908. Competitors such as the Freeport Sulphur Company quickly emerged and began to use the Frasch Process to extract sulfur from other nearby salt dome sites. The Union Sulphur Company tried to stop the Freeport Sulphur Company by suing on the basis of later patents that improved upon the original patents. The Delaware District Court largely sided with the Union Sulphur Co. The Third Circuit Court of Appeals, however, reversed the district court, concluding that the new patents were not really new inventions, but merely extensions of the original expired patents. Union Sulphur appealed to