Thermal, spectroscopy, and morphological studies on polymorphic crystals in poly(heptamethylene terephthalate)

Kai C. Yen, Eamor M. Woo

Research output: Contribution to journalArticle

12 Citations (Scopus)

Abstract

Polymorphism and its influential factors in poly(heptamethylene terephthalate) (PHepT) were probed using differential scanning calorimetry (DSC), Fourier-transform infrared (FTIR) spectroscopy, and wide angle X-ray diffraction (WAXD). PHepT exhibits two crystal types (α and β) upon crystallization at various isothermal melt-crystallization temperatures (Tcs) by quenching from different Tmaxs (maximum temperature above Tm for melting the original crystals). Melt-crystallized PHepT with either initial α- or β-crystal by quenching from Tmax lower than 110 °C leads to higher fractions of α-crystal, but crystallization from Tmax higher than 140 °C leads to higher fractions of β-crystal. In addition to Tmax, polymorphism in PHepT is also influenced by crystallization temperature (Tc = 25-75 °C). When PHepT is melt-crystallized from a high Tmax = 150 °C (completely isotropic melt), it shows solely β crystal for higher Tc, and solely the α-crystal for Tc < 25 °C; in-between Tc = 25 and 35 °C, mixed fractions of both α- and β-crystals. However, by contrast, when PHepT is melt-crystallized from a lower Tmax = 110 °C, it shows α-crystal only at all Tcs, high or low.

Original languageEnglish
Pages (from-to)662-669
Number of pages8
Journalpolymer
Volume50
Issue number2
DOIs
Publication statusPublished - 2009 Jan 16

All Science Journal Classification (ASJC) codes

  • Organic Chemistry
  • Polymers and Plastics
  • Materials Chemistry

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