Editing Polypropylene (section)

===Thermal properties===
The melting point of polypropylene occurs in a range, so the melting point is determined by finding the highest temperature of a [[differential scanning calorimetry]] chart. Perfectly isotactic PP has a melting point of {{convert|171|C|abbr=on}}. Commercial isotactic PP has a melting point that ranges from {{convert|160|to|166|C|F|abbr=on}}, depending on [[atactic]] material and crystallinity. [[Syndiotactic]] PP with a crystallinity of 30% has a melting point of {{convert|130|C|abbr=on}}.<ref name="Maier">{{Cite book|last1 = Maier|first1 = Clive|last2 = Calafut|first2 = Teresa|title = Polypropylene: the definitive user's guide and databook|page = 14|publisher = William Andrew|year = 1998|url = https://books.google.com/books?id=AWaSJd9Non8C&pg=PA14|isbn = 978-1-884207-58-7}}</ref> Below 0&nbsp;°C, PP becomes brittle.<ref name=Kaiser2011p247>{{cite book |last1=Kaiser |first1=Wolfgang |title=Kunststoffchemie für Ingenieure von der Synthese bis zur Anwendung |trans-title=Plastics chemistry for engineers from synthesis to application |language=de |year=2011 |publisher=Hanser |location=München |isbn=978-3-446-43047-1 |edition=3rd |page=247 }}</ref>

The thermal expansion of PP is significant, but somewhat less than that of polyethylene. <ref name=Kaiser2011p247/>