کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
5189602 1381189 2005 11 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Mechanism and kinetics of the free radical ring-opening polymerization of cyclic allylic sulfide lactones
موضوعات مرتبط
مهندسی و علوم پایه شیمی شیمی آلی
پیش نمایش صفحه اول مقاله
Mechanism and kinetics of the free radical ring-opening polymerization of cyclic allylic sulfide lactones
چکیده انگلیسی
The polymerization of 7-, 8- and 11-membered lactones, 6-methylene-1,4-oxathiepan-7-one, 3-methylene-1,5-oxathiocan-2-one and 3-methylene-1-oxa-5-thiacycloundecan-2-one in benzene at 70, 40-70 and 40-65 °C, respectively, is presented. All polymerizations proceeded with complete ring-opening up to approximately 25% conversion, where insoluble polymer was formed. Evidence is given attributing polymer double bond loss to crosslinking, although redistribution of the molecular weights via addition to polymer double bonds followed by β-fragmentation also appears to occur for polymerizations of the 8- and 11-membered lactones. Michael adducts of lactones with 2-methyl-2-propanethiol were prepared as models for chain-transfer products of hydrogen abstraction by carbon-centred radicals. Polymerization rates were found to increase marginally with ring size. Arrhenius parameters obtained for the polymerizations of the 8- and 11-membered lactones indicated that the addition step was more important than fragmentation in determining the rate of propagation.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Polymer - Volume 46, Issue 26, 12 December 2005, Pages 12046-12056
نویسندگان
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