Melting temperature and enthalpy of isotactic polypropylene

✍ Scribed by J.G. Fatou

• Publisher: Elsevier Science
• Year: 1971
• Tongue: English
• Weight: 408 KB
• Volume: 7
• Category: Article
• ISSN: 0014-3057
• DOI: 10.1016/0014-3057(71)90138-8

✦ Synopsis

The fusion process, melting temperature and heat of fusion of carefully crystallized fractions of isotactic polypropylene (molecular weights from 5"4 × 10" to 2.2 x 10 ~) have been investigated. The equilibrium melting temperature, obtained by the extrapolation method in experiments involving very low degrees of crystallinity, corresponds to 208 °. The fusion enthalpy was found to be 1.386 cal/mole. This low value and the high depression of Tm° suggest a relatively high interfacial energy; a value of 285 erg/cm-" is estimated for cr,c. * Paper presented before the IUPAC International Symposium on Macromolecules held at Leiden (The Netherlands) August 31-September 4, 197031-September 4, . 1057 * We express our gratitude to Dr. Mandelkern for the analysis of some of these samples in his laboratory and for the suggestion that some low enthalpy values may be due to degradation.