ISSN:
1022-1352
Keywords:
Chemistry
;
Polymer and Materials Science
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
,
Physics
Notes:
Well characterized poly[bis(p-methoxyphenoxy)phosphazene] (PB(4-MeO)PP) has been investigated employing X-ray diffraction and differential scanning calorimetry (DSC). The DSC heating scan of the original PB(4-MeO)PP specimen exhibits one exotherm at 110°C and two endotherms at 106°C and 126°C, respectively. Only a single endotherm at 131°C appears on the second heating. X-ray diffraction measurements at elevated temperature reveal that PB(4-MeO)PP crystal is monoclinic (β-form) with unit cell dimensions a = 2,47 nm, b = 1,98 nm, c = 0,983 nm and y = 102° in the range of 106-126°C. Initially PB(4-MeO)PP specimens are observed to be orthorhombic (α-form) with a = 2,39 nm, b = 1,79 nm and c = 0,983 nm. The crystal transforms at 106°C and then changes into the β-form at 110°C according to DSC measurements. At 126°C the β-form crystal changes into a mesophase with an intermolecular distance of 1,44 nm at 150°C. The 3-dimensional orthorhombic γ-form with a = 2,21 nm, b = 2,01 nm and c = 0,963 nm is found at room temperature after specimens are cooled through T(1) = 126°C from the mesophase.
Additional Material:
6 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/macp.1994.021950123
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