کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
1397041 984213 2005 7 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
On a novel tentative stereochemical microstructure based explanation of β relaxation of poly(vinylchloride) (PVC)
موضوعات مرتبط
مهندسی و علوم پایه شیمی شیمی آلی
پیش نمایش صفحه اول مقاله
On a novel tentative stereochemical microstructure based explanation of β relaxation of poly(vinylchloride) (PVC)
چکیده انگلیسی

A set of PVC samples with various stereochemical microstructures, especially the mmmr and the mmmmrx (x = m or r placement) repeating stereosequences, termini of isotactic sequences, has been prepared whether by changing the temperature of polymerization or by SN2 substitution reaction which was demonstrated to occur through a highly stereospecific mechanism. The stereochemical microstructures were accurately analysed by 13C NMR spectroscopy. For purposes of stating the microstructure/β relaxation relationship, the mechanical behaviour of all samples was studied by a dynamic mechanical thermal analyser (DMTA). The results are discussed on the ground of earlier fundamental contributions within the framework of the property/stereochemical microstructure relationships as abundantly studied in our laboratory. Basically it is shown that β relaxation decreases in both temperature and intensity with the content of the aforementioned microstructures, thereby suggesting that relaxation to stem from the enhanced free volume and favoured rotational motion facilities of the mmmr pentad under GTGTTG−TT conformation.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: European Polymer Journal - Volume 41, Issue 12, December 2005, Pages 2824–2830
نویسندگان
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