کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
5186877 1381115 2005 16 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Simulations of the mobile phase of polyethylene
موضوعات مرتبط
مهندسی و علوم پایه شیمی شیمی آلی
پیش نمایش صفحه اول مقاله
Simulations of the mobile phase of polyethylene
چکیده انگلیسی

Results are presented from atomistic molecular dynamics simulations of the mobile pseudo-hexagonal phase of polyethylene, which occurs under conditions of elevated pressure and temperature. Three different types of model are considered, all of which employ periodic boundary conditions. The first model consists of n-alkane sequences (48×-C24H48-) that are bonded across the simulation box boundaries to produce chains that are effectively infinite in extent. On heating, at high pressure, this system displays a rotator phase, in which the chains retain an all-trans conformation, and rotate as semi-rigid units. A second model, consisting of finite n-alkanes (48×C24H50) displays the same behaviour at low temperatures, but at high temperature and pressure forms a conformationally disordered rotator phase, characterised by a large proportion of gauche defects and a significant lattice expansion. The final model considered contains long n-alkanes (24×C102H206) which contain jog defects and each pass twice through the simulation box. This model forms a conformationally disordered rotator phase at high temperature and ambient pressure. The behaviour of the three models, in terms of the variations in chain conformation and rotational and translational dynamics, are compared. The conformationally disordered phases provide useful representations of the experimentally observed mobile phase.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Polymer - Volume 46, Issue 24, 21 November 2005, Pages 11035-11050
نویسندگان
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