کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
5187522 1381131 2005 9 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Rheological study of carbon nanofiber induced physical gelation in polyolefin nanocomposite melt
موضوعات مرتبط
مهندسی و علوم پایه شیمی شیمی آلی
پیش نمایش صفحه اول مقاله
Rheological study of carbon nanofiber induced physical gelation in polyolefin nanocomposite melt
چکیده انگلیسی
The rheological behavior of nanocomposites based on elastomeric ethylene-propylene (EP) random copolymer (84.3 wt% P) and well-dispersed modified carbon nanofibers (MCNFs) with concentrations from 0.5 to 20 wt% were studied by oscillatory-shear rheometry at varying temperatures. At relatively low temperatures, the entanglement density of the polymer chains appeared to increase with filler concentration, ensuring strong MCNF-polymer interactions. At elevated temperatures, pronounced deviations from the ideal melt behavior in the low frequency domain (i.e. positive slopes of the tan δ(ω) curves) were observed, indicating the formation of a three-dimensional percolated network. Following the Winter-Chambon criterion, the transition from pseudo-solid-like to liquid-like behavior (i.e. the critical gel point) upon cooling was determined. The physical gelation induced by MCNFs is a thermo-reversible phenomenon and its origin can be traced to the interactions of nanofillers, where the percolation temperature decreases with filler concentration. Abrupt changes in the critical gelation temperature, the stiffness of the gel and the relaxation exponent were observed in nanocomposites with MCNF loading above 10 wt%. This behavior indicates a change of the mechanism of physical gelation at high MCNF loadings that can be explained by the concept of bridge formation of polymer segments between two adjacent nanofillers in concentrated nanocomposites.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Polymer - Volume 46, Issue 25, 28 November 2005, Pages 11591-11599
نویسندگان
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