کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
5205445 1502930 2017 6 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Material PropertiesDetermination of plateau moduli and entanglement molecular weights of ultra-high molecular weight isotactic polypropylene synthesized by Ziegler-Natta catalyst
موضوعات مرتبط
مهندسی و علوم پایه شیمی شیمی آلی
پیش نمایش صفحه اول مقاله
Material PropertiesDetermination of plateau moduli and entanglement molecular weights of ultra-high molecular weight isotactic polypropylene synthesized by Ziegler-Natta catalyst
چکیده انگلیسی

Ziegler-Natta catalysis was employed to prepare isotactic polypropylenes (iPPs) with various viscosity average molecular weight Mη, where Mη exceeds 1 000 000 g/mol. The viscoelastic properties of the synthesized ultra-high molecular weight iPPs (UHMWiPPs) were investigated by means of oscillatory rheometry. Due to the polydispersity of these polymers that derived from multi-sites catalyst, the UHMWiPPs rheological parameters, including Arrhenius activation energy Ea, plateau modulus GN0, as well as the molecular weight between entanglements Me, were compared with that of the reported monodisperse iPPs. We critically evaluated the typical methods for the experimental determination of GN0 for polydisperse UHMWiPPs with linear architecture and concluded that the preferred method for UHMWiPP was the extrapolation integration method, which gave an average value of GN0 = (4.9 ± 0.3) × 105 Pa and Me = (6300 ± 400) g/mol. The polydipersity was proved to be acceptable for the UHMWiPP system in this research. However, the rheological measurements should be operated with caution because the temperature window was very narrow and the UHMWiPPs were extremely sensitive to thermal oxidative degradation during the tests.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Polymer Testing - Volume 60, July 2017, Pages 260-265
نویسندگان
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