Synthesis Of 3,3’-dimethyl(p-guanidinyl)dicyclohexyl Methane And Its Application In Epoxy Resin

Epoxy resin is a widely used thermosetting resin.Epoxy curing agents are an important part of epoxy resins,it also have high research value.This article reviews the research progress of epoxy resin and its curing agent.Dicyandiamide is a typical curing agent of latent epoxy resin.However,the high curing temperature of dicyandiamide limits the use of dicyandiamide,and the melting of dicyandiamide and epoxy resin is poor.3,3’-dimethyl-4,4’-diaminodicyclohexyl methane（DMDC）is a kind of lipid cycline curing agent.Its six-membered ring structure has the characteristics of benzenoid rigidity and hardness.And it has more space conformation and better flexibility.Starting from the molecular structure of curing agent,a new type of epoxy resin curing agent 3,3’-dimethyl（biguanide）was prepared by using dicyandiamide and DMDC as raw materials.It gives more excellent chemical and physical properties to the curable.And studied the kinetics of non-isothermic cure of 3,3’-dimethyl（p-guanidinyl）dicyclohexyl methane/epoxy resin systems,and tested the epoxy resin system mechanical properties.The main work is as follows:From the perspective of molecular structure,using dicyandiamide and DMDC as raw materials,an addition reaction was performed under acidic conditions to obtain a novel epoxy resin curing agent 3,3’-dimethyl（p-biguanidine）dicyclohexylmethane.Through the research method of L₉（3³）orthogonal experiment,obtained the best synthesis conditions:The reaction temperature is 140℃,the reaction time is 9h,the pH value of the solution is2.5,and the highest yield is 80.3%.The product was detected by FT-IR and 1H-NHR,the final validation of the final product is 3,3’-dimethyl（p-guanidinyl）dicyclohexyl methane.By differential scanning calorimetry（DSC）measured two 3,3’-dimethyl（p-guanidinyl）dicyclohexyl methane/epoxy resin system non isothermal curing,calculate the3,3’-dimethyl（p-guanidinyl）dicyclohexyl methane/epoxy resin system for 4.6kJ/mol.Using n-stage kinetic model and autocatalytic model for fitting and verification,finally,the autocatalytic model coincides with the experimental curve.So we can use the autocatalytic model to describe 3,3’-dimethyl（p-guanidinyl）dicyclohexyl methane/epoxy resin system.By using the extrapolation method,the gel temperature T_gel,curing temperature T_cureure and post treatment temperature T_treatreat were determined respectively:173.2℃,187.6℃ and 202.3℃.At the same time studied the thermodynamic properties of the 3,3’-dimethyl（p-guanidinyl）dicyclohexyl methane/epoxy resin system,and thermogravimetric analysis of the 3,3’-dimethyl（p-guanidinyl）dicyclohexyl methane/epoxy resin system.The results showed that the thermal decomposition temperature of the 3,3’-dimethyl（p-guanidinyl）dicyclohexyl methane/epoxy resin system when the weight loss reached5%was 358℃.Based on 3,3’-dimethyl（p-guanidinyl）dicyclohexyl methane/epoxy resin system for mechanical properties testing system of tensile strength and bending strength than dicyandiamide/epoxy resin system was improved.This is due to the rigidity and hardness of the six membered ring structure,which is similar to the benzene ring.The impact strength of the system is higher than that of dicyandiamide/epoxy resin system.The introduction of the six membered ring structure also increases the spatial conformation of the system.