کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
5187566 1381131 2005 8 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Isothermal crystallization of intercalated and exfoliated polyethylene/montmorillonite nanocomposites prepared by in situ polymerization
موضوعات مرتبط
مهندسی و علوم پایه شیمی شیمی آلی
پیش نمایش صفحه اول مقاله
Isothermal crystallization of intercalated and exfoliated polyethylene/montmorillonite nanocomposites prepared by in situ polymerization
چکیده انگلیسی

Polyethylene/montmorillonite (PE/MMT) nanocomposites with different dispersion states of MMT were prepared by in situ polymerization. Isothermal crystallization of the intercalated nanocomposite, in which the PE chains were confined in the MMT layers, was studied and was compared with that of the exfoliated nanocomposite. It is observed that the intercalated sample has longer induction period, longer crystallization half time and larger crystallization activation energy than the exfoliated sample, showing that crystallization of PE is retarded due to confinement of the MMT layers. Analysis of crystallization kinetics shows that Avrami exponent (n) increases gradually with crystallization temperature. However, the maximal value of n is 2.0 for the intercalated sample, but it can reach 3.0 for the exfoliated sample. It is inferred that the stems of the PE crystals confined in the MMT layers are parallel to the MMT layers. The Hoffman-Weeks extrapolation method cannot be applied in the intercalated sample because of the small lateral surface of the PE crystals. Based on the depression of the melting temperature, the specific free energy of the PE/MMT interface was estimated, which is about 1.0 mJ/cm2, much smaller than the free energy of the lateral surface of PE crystals. This is attributed to the origin of the strong nucleation effect of MMT.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Polymer - Volume 46, Issue 25, 28 November 2005, Pages 11978-11985
نویسندگان
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