Study On The Synthesis Of Polyether Non-isocyanate Polyurethane With Urethane

In this paper,methyl 4,4'-diphenylmethane dicarbamate(MDC)was synthesized by methoxycarbonylation;non-isocyanate polyurethane elastomer was prepared by transesterification of MDC with polytetrahydrofuran ether glycol(PTMG),carring out the optimal synthesis process of synthetic elastomers,and characting the properties of elastomers synthesized under the optimal process;the polyurethane prepolymer was prepared by transesterification of MDC and PTMG to modify the epoxy resin(E-44)as the matrix adhesive,investigating the effects of polycondensation time,E-44 dosage and curing agent on the mechanical and thermal properties of the adhesive.The main research contents are as follows:(1)Using dimethyl carbonate(DMC)and 4,4'-diaminodiphenylmethane(MDA)as raw materials to synthesize methyl 4,4'-diphenylmethanedicarbamate(MDC),and optimized the polymerization process;The results showed that:the optimum reaction temperature is 160°C,lead acetate is catalyzed and the amount was 6%of MDA,the optimal molar ratio of DMC to MDA is 20:1,and the reaction time is 2 h.Under this process,MDA conversion rate reaches 100%,and the yield of MDC reaches 96.6%.(2)Using 4,4'-diphenylmethane dicarbamate(MDC)and polytetrahydrofuran ether glycol(PTMG)as raw materials to synthesize the non-isocyanate polyurethane elastomer by transesterification,and discussing the polymerization process;The results show that:the best prepolymerization temperature is 145°C,the prepolymerization time is 1h,the polycondensation temperature is 190°C,the polycondensation time is 3h,catalyzed with stannous octoate,and the amount is 0.2%of the total raw material mass,the molar ratio of PTMG to MDC is 1:1;under this process,the intrinsic viscosity of the product is 87.31 mL·g-1,the Shore hardness is 81.28 H_A,the tensile strength is3.65 MPa,the elongation at break is 457.9%,and Mn is 5.25×10~4,Mw is 1.16×10~5,and the molecular weight distribution index is 2.21.(3)Using 4,4'-diphenylmethane dicarbamate methyl ester(MDC)and polytetrahydrofuran ether glycol(PTMG)as raw materials under the catalysis of stannous octoate to synthesize non-isocyanate polyurethanes,and epoxy resin(E-44)the adhesive was prepared by reaction;and exploring the effects of polycondensation time,E-44 dosage and curing agent on the mechanical and thermal properties of the adhesive.The results showed that:the synthetic adhesive has better bonding effect and mechanical properties when curing with hexamethylenediamine and polyurethane adopts 2h polycondensation process;the increase in the amount of E-44 can greatly enhance the bond strength of the adhesive.;using an addition polymerization type curing reaction mechanism and curing with m-xylylenediamine,the obtained adhesive has better mechanical properties and thermal properties.