کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
5186749 1502552 2008 6 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Cooperative rearranging region size in semi-crystalline poly(l-lactic acid)
موضوعات مرتبط
مهندسی و علوم پایه شیمی شیمی آلی
پیش نمایش صفحه اول مقاله
Cooperative rearranging region size in semi-crystalline poly(l-lactic acid)
چکیده انگلیسی

The amorphous phase geometrically confined at the nanometric length scale in semi-crystalline polymers exhibits different conformational dynamics with respect to the pure amorphous situation. In this work, we have studied the influence of the crystalline phase on the structural relaxation phenomena occurring in the amorphous phase by characterizing the cooperative rearranging region (CRR) in poly(l-lactic acid), PLLA, a well known biodegradable polyester. More particularly, the evolution of the characteristic cooperativity length ξTg at the glass transition is investigated in function of the crystallinity degree using Temperature Modulated Differential Scanning Calorimetry, TMDSC. Thermal analyses have been performed on PLLA cold crystallized at 80 °C for different durations in order to obtain a crystallinity degree varying between 0 and 42%. We show that two types of mobile amorphous phases exist: the amorphous matrix and the amorphous fraction trapped in the spherulites. For this latter one, a clear confinement effect is shown despite the fact that the amorphous domain size is larger than ξTg. This behavior is attributed to the chemical connection between the mobile and the rigid fraction of the polymer.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Polymer - Volume 49, Issues 13–14, 23 June 2008, Pages 3130-3135
نویسندگان
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