کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
10609892 984736 2011 12 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Dielectric behavior of some aromatic polyimide films
موضوعات مرتبط
مهندسی و علوم پایه شیمی شیمی آلی
پیش نمایش صفحه اول مقاله
Dielectric behavior of some aromatic polyimide films
چکیده انگلیسی
Aromatic polyimides were prepared by polycondensation reaction of two aromatic diamines, such as 4,4′-diaminodiphenylmethane (DDM) and 3,3′-dimethyl-4,4′-diaminodiphenylmethane (MDDM), with aromatic dianhydrides, such as 4,4′-isopropylidene-diphenoxy-bis(phthalic anhydride) (6HDA), benzophenonetetracarboxylic dianhydride (BTDA) and hexafluoroisopropylidene-bis (phthalic anhydride) (6FDA). These polymers are soluble in polar aprotic solvents and can be cast into thin films from such solutions. The polyimides show high thermal stability, with decomposition temperature being above 430 °C in air, and high glass transition temperature being in the range of 200-287 °C. The free standing films, having the thickness of tens of micrometers, exhibited good mechanical and electrical insulating properties. The dielectric constant, molecular mobility and AC conductivity of thin films prepared from these polymers were investigated in detailed. The study of their dielectric behavior evidenced low dielectric constant values, in the range of 2.88-3.48 at 1 Hz at room temperature, and three relaxation processes (γ,β1 and β2) were observed at sub-glass temperatures for polyimides based on 6HDA and 6FDA and only two (γ and β) relaxations were detected for polyimides based on BTDA. The cooperativity of the molecular motions associated with the relaxation processes was discussed.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: European Polymer Journal - Volume 47, Issue 5, May 2011, Pages 1186-1197
نویسندگان
, , , ,