کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
9559250 1381146 2005 10 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Formation mechanism of shish in the oriented melt (I)-bundle nucleus becomes to shish
موضوعات مرتبط
مهندسی و علوم پایه شیمی شیمی آلی
پیش نمایش صفحه اول مقاله
Formation mechanism of shish in the oriented melt (I)-bundle nucleus becomes to shish
چکیده انگلیسی
We have solved the molecular mechanism of the formation of shish of isotactic-polypropylene (iPP) and polyethylene (PE) from the sheared melt based on kinetic study by means of polarizing optical microscope. We found that the rate determining process for the formation of shish is a nucleation process in the most range of degree of supercooling (ΔT) except for large ΔT of PE. We have shown a direct evidence of the formation of bundle nucleus from the oriented melt, which is consisted of elongated chains caused by artificial pins. For polymers, a universal mechanism of nucleation from the isotropic or oriented melt was proposed. We also found that there is a critical shear rate for the formation of shish. This experimental fact indicates that the shish will be formed when the elongation of chains will overcome the conformational relaxation of chains and chain conformation within the oriented melt is kept liquid crystal like one.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Polymer - Volume 46, Issue 5, 14 February 2005, Pages 1675-1684
نویسندگان
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