Study On Diallyl-bearing Epoxy Resin Sulfur Curing Mechanism And Modification

Diglycidyl ether of4,4’-diallyl bisphenol A (DADGEBA) is a novelepoxy resin which has both double bond and epoxide, which results somefunctions that are different from general epoxy resins. The functions ofepoxide group are good strength and excellent thermal property, and thefunctions of double bond are easily modified, double curing and togethercrosslinking. DADGEBA can be used for synthetizing organic siliconepoxy resin that can resist high temperature, realizing epoxy splicingbetween rubber and metal, so DADGEBA is a very wide applicationprospect.In this paper, DSC and FTIR were used to measure exothermic andchemical groups change in E-51/S, DABPA/S,DADGEBA/Ssystems.NIR and1H-NMR were adopted to study the mercapto groups inDABPA/S system. The mass spectrum and GPC were used to deduce themolecular weight and structure of DABPA/S cured. Through these studyon the reaction process of model compounds (E-51, DABPA, DADGEBA)and sulfur, we obtained the curing reaction mechanism of DADGEBA/Ssystem, as follow: sulfur homolysis-radical transfer-mercapto groups-rang-open polymerization of epoxy group/crosslinking doublebond-radical combination.The curing kinetics of DADGEBA/S was studied by non-isothermaland isothermal DSC. The kinetic mechanism equations were determinedusing autocatalytic models and nth-order reaction model. DSCmeasurement showed that the curing process of DADGEBA/S systemcontains two steps because of the double exothermic peaks in DSC curve.The model data simulation results indicated that the esták-Berggren(SB)model had a great distinction with the experimental data. Isothermal DSCanalysis showed that the curing reactions followed Kamal’s autocatalyticmodel when the reaction temperature was below210oC, and when thetemperature was above210oC the nth-order model can be used todescribe the curing reaction process of the DADGEBA/S system perfectly.The two kinetic equations in the entire reaction process of DADGEBA/Ssystem are consistent with the two-step reaction mechanisms of the samesystem.Cured DADGEBA has good thermal stabilities and poor mechanicalproperties because of heavy brittleness. In this article, PUcopolymerization and rubber blending methods were used to modifyDADGEBA. Through study translate temperature, thermal decompositiontemperature and mechanical properties of DDM and sulfur curedmodified DADGEBA, we gained the best addition content of flexible chain. At the same time, the article researched DADGEBA tougheningmechanisms with AFM and SEM, as follow: more active point-co-crosslinking-microphase separation.