Morphological changes in thermoplastic polyurethanes during heating

✍ Scribed by P. R. Laity; J. E. Taylor; S. S. Wong; P. Khunkamchoo; M. Cable; G. T. Andrews; A. F. Johnson; R. E. Cameron

• Publisher: John Wiley and Sons
• Year: 2006
• Tongue: English
• Weight: 203 KB
• Volume: 100
• Category: Article
• ISSN: 0021-8995
• DOI: 10.1002/app.22644

✦ Synopsis

Abstract

This work investigated the thermal behavior of a series of thermoplastic poly(ether‐urethane)s containing 36–71% by weight hard segments derived from 4,4′‐methylene‐bisphenylisocyanate and butane‐1,4‐diol, with poly(tetramethylene oxide) soft segments. In all materials studied, differential scanning calorimetry revealed the presence of a T~1~ endotherm ∼20–30°C above the annealing temperature. Morphological changes during heating were observed using small‐angle X‐ray scattering; the data was analyzed using “globular” models based on a one‐dimensional statistical lattice or the Percus–Yevick description of liquids, both of which appeared to provide good descriptions of these materials. The results indicated that the T~1~ endotherm coincided with the onset of morphological changes during heating. Possible explanations are discussed, based on the melting of small hard‐segment crystals or an activation energy associated with transient segmental mixing. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 779–790, 2006