کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
2503112 1557416 2012 8 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Investigating the effect of humidity on the α-relaxations of low-density polyethylene using dielectric spectroscopy
موضوعات مرتبط
علوم پزشکی و سلامت داروسازی، سم شناسی و علوم دارویی علوم دارویی
پیش نمایش صفحه اول مقاله
Investigating the effect of humidity on the α-relaxations of low-density polyethylene using dielectric spectroscopy
چکیده انگلیسی

A previous work from our lab reported the higher sorption of lipophilic preservatives in LDPE form-fill-seal packs that were stored at 75% relative humidity (RH) as against 25% RH. The aim of the present work was to investigate structural changes taking place in LDPE on exposure to higher humidity. The crystallinity of LDPE, determined by differential scanning calorimetry, was found to be similar for the packs charged at both humidity conditions. Dielectric spectroscopy (1.0E−02 Hz to 1.0E02 Hz in the temperature range of 75–87 °C), however, showed faster α relaxation of LDPE films exposed to higher humidity. The activation energy of α relaxations was lower at 75% RH (99.735 kJ/mol) than at 25% RH (113.112 kJ/mol) after two weeks of storage. This work presents previously unreported evidence of the plasticization effect of water on LDPE, using dielectric spectroscopy. Furthermore, changes in α relaxation on exposure to humidity support the latest theory of its origin to be from the constrained amorphous regions. The authors suggest the employment of extreme humidity conditions (low and high), during accelerated stability studies of aqueous products in plastic packs to track the sorption loss of formulation components.

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ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: International Journal of Pharmaceutics - Volume 422, Issues 1–2, 17 January 2012, Pages 302–309
نویسندگان
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