کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
5186325 | 1381101 | 2009 | 7 صفحه PDF | دانلود رایگان |
Syndiotactic poly(p-fluoro-styrene) (s-PPFS) has been prepared with a polymerization procedure which allows reaching high average molecular masses and satisfactory yields. The polymorphic behavior of the polymer has been mainly studied by X-ray diffraction, calorimetric and infrared analyses. The main crystalline phase of s-PPFS, obtained by melt processing or cold-crystallization, exhibits trans-planar chains, is orthorhombic (a = 9.5 à , b = 28.7 à , c = 5.1 à ) and melts at nearly 320 °C. The X-ray analysis shows a strict analogy of this orthorhombic phase with the β phase of s-PS, also as for the occurrence of two limit ordered (βâ³) and disordered (βâ²) modifications, which differ for the intensity of reflections characterized by h + k = 2n + 1. A metastable crystalline phase, also exhibiting trans-planar chains, has been observed for as-polymerized samples as well as for amorphous samples crystallized by sorption of toluene or 1,4-difluoro-benzene. Mainly on the basis of solvent sorption and desorption experiments, it is suggested that this metastable phase is a co-crystalline phase with the low-molecular-mass guest molecules.
Journal: Polymer - Volume 50, Issue 8, 9 April 2009, Pages 1901-1907