Determination of unsaturation in ethylene-propylene terpolymers and butyl rubber by time-averaged 1H n.m.r. measurements |
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| Authors: | Yasuyuki Tanaka Hisaya Sato Yukio Ozeki Masaru Ikeyama Takefumi Sato |
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| Affiliation: | Department of Textiles and Polymer Science, Faculty of Technology, Tokyo University of Agriculture and Technology, Koganei, Tokyo, Japan;Tokyo Research Laboratory, Japan Synthetic Rubber Co., Ikuta, Kawasaki, Japan |
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| Abstract: | The time-averaged 1H n.m.r. spectra of ethylene-propylene-dicyclopentadiene, ethylene-propylene-ethylidene norbornene and isobutylene-isoprene copolymers were measured. Assignments of the olefinic resonances were carried out by comparing the spectra with those of each homopolymer and strarting monomers. The concentration of the olefinic unit in copolymer was determined by measuring the intensity ratio between the olefinic proton signal and the signal of trichloroethylene which was added as an internal standard of intensity measurements. The concentrations of unsaturation in copolymers determined by using the iodine-mercuric acetate method were proportional to those determined by the n.m.r. method. The accuracy and precision of the n.m.r. measurements were shown to be better than 10% for a mixture of polyisobutylene and polyisoprene containing 1.24 mol % of unsaturation as a model compound of isobutylene-isoprene copolymer. |
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