کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
5204547 1381964 2006 9 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
The changing anisotropy character of weathered low-density polyethylene films recognized by quasi-static and ultrasonic mechanical testing
موضوعات مرتبط
مهندسی و علوم پایه شیمی شیمی آلی
پیش نمایش صفحه اول مقاله
The changing anisotropy character of weathered low-density polyethylene films recognized by quasi-static and ultrasonic mechanical testing
چکیده انگلیسی

Unstabilised polyethylene films used for greenhouse covering have been exposed outdoors under the severe weathering conditions in the Sahara.The chemical and the morphological changes followed by infrared spectroscopy and by differential scanning calorimetry (DSC) show that the damages caused by oxidation to the tie molecules increase crystallinity and lead to a severe deterioration of the mechanical properties.The mechanical aspect of aging was studied by using standard quasi-static (QS) tensile testing measurements and by a non-destructive method based on ultrasound (US). This latter technique consists of measuring velocities and attenuations of ultrasonic waves propagating in several directions in the film plane.Both methods show the changing anisotropic character of the films with aging. The transverse direction has been found to be the principal axis of anisotropy consequently to a little more significant chain orientation in this direction acquired during processing.The connection between the chemical aspect of aging and the mechanical one (i.e. the viscoelastic properties and the anisotropic character) is discussed.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Polymer Degradation and Stability - Volume 91, Issue 8, August 2006, Pages 1887-1895
نویسندگان
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