X-ray photoelectron spectroscopy and Raman spectroscopy were' used to determine the chemical change of polyphenylsilsesquioxane (PPSQ) during pyrolysis in flowing nitrogen. Two temperature ranges were found for py...X-ray photoelectron spectroscopy and Raman spectroscopy were' used to determine the chemical change of polyphenylsilsesquioxane (PPSQ) during pyrolysis in flowing nitrogen. Two temperature ranges were found for pyrolysed PPSQ below and above 600degreesC, respectively. The former is related to the rearrangement of PPSQ backbone and the latter reflects that most of backbone structure of PPSQ might be broken down and unorganized. Carbon formed in carbonization of PPSQ sample pyrolysed at 900degreesC should be sp(3) bonded carbon with crystallite size effects or defects.展开更多
To improve the dispersion of silica in polypropylene（PP） matrix and to avoid physical loss of the antioxidants, nanosilica with dendric polyamidoamines on the surface（SG-PAMAM） was synthesized by using divergent m...To improve the dispersion of silica in polypropylene（PP） matrix and to avoid physical loss of the antioxidants, nanosilica with dendric polyamidoamines on the surface（SG-PAMAM） was synthesized by using divergent method. Then nanosilica-immobilized antioxidant（SG-PAMAM-AO） was prepared by grafting 2,6-di-tert-butyl-4-aminophenol which was derived from 2,6-di-tert-butyl-4-phenol（AO）. The SG-PAMAM-AO was added into PP by melt mixing to study the aging property. The oxidation induction time of PP/SG-PAMAM-AO and PP/AO compounds was measured. It was found that the antioxidant property of the SG-PAMAM-AO was superior to that of AO. According to the changes of carbonyl absorption before and after photo-thermal aging, the photo-thermal oxidative stability of PP/SG-PAMAM-AO was much higher than that of PP, PP/SG-PAMAM and PP/AO.展开更多
基金The National Natural Science Foundation of China (Grant No. 20074039) and National 863 High-technology Project as well as the Science Foundation of PPLAS(No, 00-B-01) are gratefully acknowledged for the financial support to this work.
文摘X-ray photoelectron spectroscopy and Raman spectroscopy were' used to determine the chemical change of polyphenylsilsesquioxane (PPSQ) during pyrolysis in flowing nitrogen. Two temperature ranges were found for pyrolysed PPSQ below and above 600degreesC, respectively. The former is related to the rearrangement of PPSQ backbone and the latter reflects that most of backbone structure of PPSQ might be broken down and unorganized. Carbon formed in carbonization of PPSQ sample pyrolysed at 900degreesC should be sp(3) bonded carbon with crystallite size effects or defects.
文摘To improve the dispersion of silica in polypropylene（PP） matrix and to avoid physical loss of the antioxidants, nanosilica with dendric polyamidoamines on the surface（SG-PAMAM） was synthesized by using divergent method. Then nanosilica-immobilized antioxidant（SG-PAMAM-AO） was prepared by grafting 2,6-di-tert-butyl-4-aminophenol which was derived from 2,6-di-tert-butyl-4-phenol（AO）. The SG-PAMAM-AO was added into PP by melt mixing to study the aging property. The oxidation induction time of PP/SG-PAMAM-AO and PP/AO compounds was measured. It was found that the antioxidant property of the SG-PAMAM-AO was superior to that of AO. According to the changes of carbonyl absorption before and after photo-thermal aging, the photo-thermal oxidative stability of PP/SG-PAMAM-AO was much higher than that of PP, PP/SG-PAMAM and PP/AO.
