کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
9559330 | 1381159 | 2005 | 10 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
Microstructure of free volume in SMA copolymers I. Free volume from Simha-Somcynsky analysis of PVT experiments
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موضوعات مرتبط
مهندسی و علوم پایه
شیمی
شیمی آلی
پیش نمایش صفحه اول مقاله
چکیده انگلیسی
The structure of the free volume and its temperature dependence between 25 and 200 °C of copolymers of styrene with maleic anhydride, SMA (0-35 mol% MA), is studied by pressure-volume-temperature (PVT) experiments and positron annihilation lifetime spectroscopy (PALS). In this first part of the work, PVT data are reported which were analysed with the Simha-Somcynsky equation of state to estimate the volume fraction of holes, h, which constitute the excess free volume. The temperature and pressure dependence of the specific volume V, the specific occupied and free volume, Vocc=(1âh)V and Vf=hV, and the corresponding isobaric expansivities and isothermal compressibilities for both the rubbery and glassy state are estimated. We obtained the unexpected results that (i) the occupied volume changes its coefficient of thermal expansion at Tg from αocc,gâ0.5αgâ1Ã10â4 Kâ1 below Tg to almost zero (â0.2Ã10â4 Kâ1) above Tg and (ii) the isothermal compressibility of the occupied volume at zero pressure below Tg is rather high, κoccâ2.5Ã10â4 MPaâ1, and decreases only slightly at Tg to about 2Ã10â4 MPaâ1 above Tg. The variation of total, occupied, and free volume parameters with the composition of the SMA copolymers is discussed.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Polymer - Volume 46, Issue 3, 26 January 2005, Pages 859-868
Journal: Polymer - Volume 46, Issue 3, 26 January 2005, Pages 859-868
نویسندگان
D. Kilburn, G. Dlubek, J. Pionteck, D. Bamford, M.A. Alam,