Abstract
Abstract The objective of this research is to study the feasibility of synthesizing polycarbonate by reacting 4-vinyl cyclohexene oxide (VCHO) with carbon dioxide.The yields and properties of copolymers were investigated. From the characteristic peak of C=O stretching at 1700 ~1800cm-1in the IR spectra, the polymer produced was confirmed as the copolymer of polycarbonate and polyether.The H1NMR spectrum shows that the main structure of cyclohxene and vinyl group of VCHO still existed in the copolymer. Results show that the optimum yield of polycarbonate produced from VCHO monomer and CO2, is about 75%. But the yield of polycarbonate by reacting butene oxide with CO2 is only 50%, and the mechanical properties are not acceptable . They are too soft to be tested. And the results show that the reactivity of epoxide decrea-ses with the chain length, the maximum carbon number of epoxide can react with CO2 is six. The yield of epoxide reacts with carbon number more than six is very low. The copolymerization reaction parameters such as temperature,pressure of CO2,the kind of main catalyst uesd, solvent and monomer were studied.Effect of the reaction parameters on the molecular weight, 10% thermal weight loss and Tg,mechanical properties (tensile strength and impact strength) of the polycar-bonate were investigated. Results show that the functional group on the side chain of cyclohexene oxide in the monomer affects the molecular weight, 10% weight thermal loss and Tg,mechanical properties of the polycarbonate. Reaction temperatures from 80~110℃ were condu-cted, it was found that the yield and molecular weight increased with the temperature. The reaction pressures from 300psi to 700psi were studied. Influence of pre-ssure is rather obvious at 90℃ than at 80℃.Results show that the cocatalyst consists of organic yttrium and organic zinc coordination will detain the yield and other properties. The main catalyst owns ligands with high polarity atoms and empty atomic orbitals may induce higher yield and higher molecular weight . Trifluoro acetic yttrium(Y(CF3COO)3) was used as the main catalyst, which has been compared with other organic yttrium catalyst in the reaction. The optimum conditions resulting best yields and molecular weight for the polycarbonate synthesized from epoxide and carbon dioxide have been studied .Effect of ligands of the catalyst on catalyst ability was investigated. Results shows that the higher the electronegativity of atoms on the substitutional group,the better the pulling electrons ability, and the higher the yield. The most effective catalyst is the Trifluoro acetic yttrium, the yield can achieve as high as 75%, Mn is between 7600 and 38000.Results explicit that the second best catalyst is acetic yttrium, its yield can achieve as 67%, Mn is between 5000 and 16000. Results show the 1,3 dioxolane is the best solvent to carry the polymerization of polycarbonate, and the yield of the polycarbonate is about 65~75%.10% weight loss temperature is about 210~260℃,the Tg distribu-tion is very irregular,which is about 90~140℃. Mechanical properties show that the optimum of tensile strengthes is in the range of 1.6MPa ~7MPa,the elongation is about 1~2%.The impact strength is about 0.35~0.45ft-lb/in.