کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
1403758 984843 2007 12 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Effects of branching characteristics and copolymer composition distribution on non-isothermal crystallization kinetics of metallocene LLDPEs
موضوعات مرتبط
مهندسی و علوم پایه شیمی شیمی آلی
پیش نمایش صفحه اول مقاله
Effects of branching characteristics and copolymer composition distribution on non-isothermal crystallization kinetics of metallocene LLDPEs
چکیده انگلیسی

The effects of branch content (BC) and copolymer composition distribution (CCD) on the non-isothermal crystallization kinetics of metallocene m-LLDPEs were studied using modified Avrami analysis, modulated differential scanning calorimetry (MDSC), and Crystaf. Several m-LLDPEs and an m-HDPE – all having comparable Mw and PDI – were experimented. In addition, a ZN-LLDPE was used for comparison purposes. The branch content, unlike the used cooling rates (2–6 °C/min), significantly affected the crystallization behavior. Crystallization peak temperature, Tcpeak, decreased linearly with increasing BC. All the m-LLDPEs showed primary and secondary crystallizations. The secondary crystallization showed to be more pronounced at high BC. The primary crystallization Avrami parameter n   for m-HDPE ranged between 3.72 and 4.50, indicating spherulitic crystal growth whereas that for the m-LLDPEs, varied from 2.02 to 5.70. The ZN-LLDPE (having broader composition distribution) offered higher values of Tconset and Tcpeak than the m-LLDPEs with similar BC, Mw, and PDI. It, unlike the m-LLDPEs and m-HDPE, fairly agreed with the crystallization kinetic model proposed by Liu et al. The lamella thickness of the m-LLDPEs, L, calculated as per Gibbs–Thomson equation, showed to be in the range 2–16 nm, depending on BC and it decreased approximately following the relationship: L (nm) = 15.0 e(−0.0498BC).

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: European Polymer Journal - Volume 43, Issue 2, February 2007, Pages 599–610
نویسندگان
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