کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
5189646 1381189 2005 8 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Evidence for spatial heterogeneities observed by frequency dependent dielectric and mechanical measurements in vinyl/dimethacrylate systems
موضوعات مرتبط
مهندسی و علوم پایه شیمی شیمی آلی
پیش نمایش صفحه اول مقاله
Evidence for spatial heterogeneities observed by frequency dependent dielectric and mechanical measurements in vinyl/dimethacrylate systems
چکیده انگلیسی

Frequency dependent dielectric measurements (FDEMS), dynamic mechanical rheometer measurements (DMA) and modulated differential scanning calorimetry (DSC) are applied to observe the formation of a spatial heterogeneity in dimethacrylate/divinylbenzene (D121/DVB) and dimethylacrylate/styrene (D121/St) network systems. The structure evolution information during the reaction, such as Tg, the dielectric relaxation and the dynamic mechanic relaxation obtained from these measurements for both systems are compared. The result shows that a spatial heterogeneity does exist in both systems. This is based on the existence of two distinct separate relaxation peaks in the dielectric spectrum, two Tg's in the DSC profile and the dynamic mechanical analysis. These two regions are ascribed to the formation of microgel regions as previously identified by dynamic light scattering and monomer/oligomer regions. The experimental spectra are affected by the comonomer structure. The breadth of the relaxation distribution of the spatial heterogeneity of the microgel region in the DVB comonomer system is extremely large compared to the large breadth in the styrene system.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Polymer - Volume 46, Issue 26, 12 December 2005, Pages 12452-12459
نویسندگان
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