کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
5189751 | 1381191 | 2006 | 11 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
Dispersion characteristics and rheology of organoclay nanocomposites based on a segmented main-chain liquid-crystalline polymer having side-chain azopyridine with flexible spacer
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کلمات کلیدی
موضوعات مرتبط
مهندسی و علوم پایه
شیمی
شیمی آلی
پیش نمایش صفحه اول مقاله
چکیده انگلیسی
The dispersion characteristics and rheology of organoclay nanocomposites based on a main-chain liquid-crystalline polymer having side-chain azopyridine with flexible spacer (PABP) were investigated using X-ray diffraction (XRD), transmission electron microscopy (TEM), and oscillatory shear rheometry. In the preparation of nanocomposites via solution blending under vigorous stirring, two commercial organoclays (Southern Clay Products) were employed: one (Cloisite 30B) treated with a surfactant (MT2EtOH) having hydroxyl groups, and the other (Cloisite 20A) treated with a nonpolar surfactant (2M2HT) having hydrogenated tallow. Also prepared, for comparison, were nanocomposites prepared by mixing PABP with natural clay (montmorillonite, MMT). The following observations were made. (i) PABP/Cloisite 30B nanocomposite has featureless XRD patterns and a very high degree of dispersion of Cloisite 30B aggregates as determined from TEM. (ii) PABP/Cloisite 20A nanocomposite has shown a conspicuous XRD reflection peak and intercalation of Cloisite 20A aggregates as determined from TEM. (iii) PABP/MMT nanocomposite has shown XRD patterns, which are virtually the same as the XRD patterns of neat PABP with a slightly increased gallery distance, and it has very poor dispersion of MMT aggregates in the matrix of PABP. The observed high degree of dispersion of Cloisite 30B aggregates in PABP/Cloisite 30B nanocomposite is attributable to the formation of hydrogen bonds between the pyridyl group of side-chain azopyridine and the hydroxyl groups in the surfactant MT2EtOH residing at the surface of Cloisite 30B. The presence of hydrogen bonds in the PABP/Cloisite 30B nanocomposite was confirmed by in situ Fourier transform infrared (FTIR) spectroscopy. It was observed via polarized optical microscopy that the liquid crystallinity of PABP in the PABP/Cloisite 30B nanocomposites was more or less intact with a very high degree of dispersion of Cloisite 30B aggregates. Oscillatory shear flow measurements of the organoclay nanocomposites prepared support the conclusions drawn from XRD, TEM, and FTIR spectroscopy.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Polymer - Volume 47, Issue 12, 31 May 2006, Pages 4400-4410
Journal: Polymer - Volume 47, Issue 12, 31 May 2006, Pages 4400-4410
نویسندگان
Wenyi Huang, Chang Dae Han,