Editing Polymer (section)

===Product failure===
[[File:Chlorine attack1.jpg|thumb|left|Chlorine attack of acetal resin plumbing joint]]
Failure of [[safety-critical]] polymer components can cause serious accidents, such as fire in the case of cracked and degraded polymer [[fuel line]]s. Chlorine-induced cracking of [[acetal resin]] plumbing joints and [[polybutylene]] pipes has caused many serious floods in domestic properties, especially in the US in the 1990s. Traces of [[chlorine]] in the water supply attacked polymers present in the plumbing, a problem which occurs faster if any of the parts have been poorly [[extruded]] or [[Injection molding|injection molded]]. Attack of the acetal joint occurred because of faulty molding, leading to cracking along the threads of the fitting where there is [[stress concentration]].
[[File:Ozone_cracks_in_tube1.jpg|thumb|Ozone-induced cracking in natural rubber tubing]]
Polymer oxidation has caused accidents involving [[medical device]]s. One of the oldest known failure modes is ozone cracking caused by chain scission when [[ozone]] gas attacks susceptible [[elastomer]]s, such as [[natural rubber]] and [[nitrile rubber]]. They possess double bonds in their repeat units which are cleaved during [[ozonolysis]]. Cracks in fuel lines can penetrate the bore of the tube and cause fuel leakage. If cracking occurs in the engine compartment, electric sparks can ignite the [[gasoline]] and can cause a serious fire. In medical use degradation of polymers can lead to changes of physical and chemical characteristics of implantable devices.<ref>{{cite journal|last1=Iakovlev|first1=V.|last2=Guelcher|first2=S.|last3=Bendavid|first3=R.|date=28 August 2015|title=Degradation of polypropylene in vivo: A microscopic analysis of meshes explanted from patients|journal=Journal of Biomedical Materials Research Part B: Applied Biomaterials|volume=105|issue=2|pages=237–248|doi=10.1002/jbm.b.33502|pmid=26315946}}</ref>

[[Nylon 6,6|Nylon 66]] is susceptible to [[acid hydrolysis]], and in one accident, a fractured fuel line led to a spillage of diesel into the road. If [[diesel fuel]] leaks onto the road, accidents to following cars can be caused by the slippery nature of the deposit, which is like [[black ice]]. Furthermore, the [[asphalt concrete]] road surface will suffer damage as a result of the diesel fuel dissolving the [[asphaltene]]s from the composite material, this resulting in the degradation of the asphalt surface and structural integrity of the road.