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
Polymer architecture crosslinked to allow flaking of the rubber and prevent damage to the paper. Polymerization of pure sulfur at higher temperatures also explains why sulfur becomes more viscous with elevated temperatures in its molten state. A polymer molecule with a high degree of crosslinking is referred to as a polymer network. A sufficiently high crosslink to chain ratio may lead to the formation of a so-called infinite network or gel, in which each chain is connected to at least one other. With the continual development of Living polymerization, the synthesis of polymers with specific architectures becomes more and more facile. Architectures