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MEASUREMENTS OF monomer reactivity ratios FOR COPOLYMERIZATION OF STYRENE AND METHYL METHACRYLATE IN CARBON DIOXIDE AT VAPOR-LIQUID EQUILIBRIUM STATE

引用

Chinese Journal of Polymer Science 2009年第3期27卷 367-374页

作者：胡春圃 Key Laboratory of Ultrafine Materials Ministry of Education School of Materials Science and Engineering East China University of Science and Technology

The monomer reactivity ratios of free radical copolymerization of styrene and methyl methacrylate in carbon dioxide at vapor-liquid equilibrium state (vlCO(2)) at 65 degrees C and under 7.5-8.5 MPa were measured. The experimental results showed that, in comparison with the data in bulk copolymerization, the monomer reactivity ratio of St in vlCO(2) increased acompanied by a somewhat decrease in that of MMA. Further analysis of the sequence distributions of these copolymers by H-1-NMR spectra indicated that there was a significant bootstrap effect in this system. The local monomer concentrations in the proximity of growing free radicals, rather than the true reactivity of monomers or free radicals, were altered by the presence of vlCO(2), leading to the change in monomer reactivity ratios.

关键词： monomer reactivity ratios Free radical copolymerization Carbon dioxide Styrene Methyl methacrylate

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Measurement of monomer reactivity ratios of D,L-3-Methylglycolide with Glycolide or D,L-Lactide

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Chinese Chemical Letters 2000年第9期11卷 815-818页

作者： Chang Ming DONG Kun Yuan QIU Zhong Wei GU Xin De FENG Department of Polymer Science and Engineering, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871 National Research Institute for Family Planning, Beijing 100081 Peking Univ Coll Chem & Mol Engn Dept Polymer Sci & Engn Beijing 100871 Peoples R China Natl Res Inst Family Plannning Beijing 100081 Peoples R China

For monomer reactivity ratios study, the copolymerization of D,L-3-methylglycolide (MG) with glycolide (GA) or D,L-lactide (LA) was carried out in bulk to a certain low conversion in the presence of stannous octoate at 140 degrees C. The copolymer compositions were determined by H-1 NMR spectroscopy. The monomer reactivity ratios were evaluated by Fineman-Ross method, Kelen-Tudos method and linear least-squares method. The monomer reactivity ratios of D,L-3-methylglycolide and glycolide or D,L-lactide are r(mg)= 0.73, r(ga)= 1.47; r(mg)= 1.71, r(la)= 0.92, respectively.

关键词： D,L-3-methylglycolide glycolide D,L-lactide ring-opening copolymerization monomer reactivity ratios

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