کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
5183807 1381029 2011 9 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Constraints in semicrystalline polymers: Using quasi-isothermal analysis to investigate the mechanisms of formation and loss of the rigid amorphous fraction
موضوعات مرتبط
مهندسی و علوم پایه شیمی شیمی آلی
پیش نمایش صفحه اول مقاله
Constraints in semicrystalline polymers: Using quasi-isothermal analysis to investigate the mechanisms of formation and loss of the rigid amorphous fraction
چکیده انگلیسی

The nanoscale phase behavior of a semicrystalline polymer is important for mechanical, thermal, optical and other macroscopic properties and can be analyzed well by thermal methods. Using quasi-isothermal (QI) heat capacity measurements, we investigate the formation behavior of the crystalline, mobile amorphous, and rigid amorphous fractions in poly(trimethylene terephthalate), PTT. The crystal and rigid amorphous phases comprise the total solid fraction in PTT at temperatures above Tg, the glass transition temperature of the mobile amorphous fraction. PTT was quasi-isothermally cooled step-wise from the melt which causes its crystalline fraction to be fixed below 451 K. Between the high temperature fulfillment of the Tg step and 451 K, the temperature dependent rigid amorphous fraction (RAF) is completely determined. For PTT, most of the RAF vitrifies between 451 K and Tg step by step during QI cooling after the crystals have formed. The constraints imposed by the crystal surfaces reduce the mobility of the highly entangled polymer chains. We suggest the vitrification of RAF proceeds outward away from the lamellar surfaces in a step by step manner during QI cooling. Upon reheating, devitrification of RAF occurs at a temperature above its previous vitrification temperature, due to the effects of densification brought by physical aging during the long period of quasi-isothermal treatment. Finally, we consider recent concepts related to jamming, which have been suggested to apply to filled polymer systems, and may also be applicable in describing constraints exerted by crystal lamellae upon the RAF.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Polymer - Volume 52, Issue 20, 12 September 2011, Pages 4562-4570
نویسندگان
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