Synthesis And Properties Of Cycloaliphatic Epoxy Resins Containing Acetal Or Ketal Bonds

Cured epoxy resins are generally used in coating,adhesives,insulation materials,composite materials,electronic packaging materials and other aspects due to good adhesive properties,heat resistance,chemical resistance and electric insulation performance.However,the characteristics of insolubility and non-fusion are intractable in some in some applications.For example,in the field of electronic packaging,the defective components packaged with epoxy resins are difficult to be replaced and in the field of composite materials,epoxy-based carbon fibre composites are often used in hi-tech products but overpriced carbon fibre can hardly be recycled and the result are the waste of resources,rising costs and environmental pollution.Given that,the exploitation of novel degradable epoxy resin becomes a natural tendency.In this thesis,we firstly used 3-Cyclohexene-1-methanol,Cyclohexanecarboxaldehyde,3-Cyclohexene-1-carboxaldehyde and Cyclohexanone as reactants and synthesized three cycloaliphatic epoxides containing acetal or ketal bonds through molecular design,moreover,three cycloaliphatic epoxides,namely Epoxide-I,Epoxide-II and Epoxide-III,were characterized by FTIR,¹H-NMR,¹³C-NMR and MS.Then,we studied their anhydride curing kinetics,where MHHPA was used as anhydride,by means of non-isothermal DSC model and obtained their curing procedures that the Epoxide-I/MHHPA system was corresponding to:125??2 h?+165??4 h?+190??4 h?,the Epoxide-II/MHHPA system:115??2h?+150??4 h?+170??4 h?,and the Epoxide-III/MHHPA system:65??2 h?+140??6h?+195??2 h?.Their apparent activation energy,determined by Kissinger method,were 76.0KJ/mol,61.4 KJ/mol and 61.5 KJ/mol,respectively.After that,we mainly investigated and discussed chemical degradation properties of three anhydride curing epoxy resins.Two parts were carried out:the first part was,compared with the Epoxide-I/MHHPA system,we found that the Epoxide-II/MHHPA system had exceeded 17%and 36%at initial decomposition temperature?IDT?and glass transition temperature(T_g-DMA),and it had a lower chemical degradation rate under the same conditions,all of which could be explained by the fact that the Epoxide-II/MHHPA system had exceeded 118%than the Epoxide-I/MHHPA system in crosslinking density.In addition,the data of the experiments showed that the chemical degradation rates could be controlled by changing acidity and constitute of solution.The other part was investigation of the effect of mixing different proportion of ERL-4221 on the Epoxide-III/MHHPA system.We prepared a series of anhydride curing epoxy resins containing gradient changed proportions between Epoxide-III and ERL-4221.Compared with simple anhydride curing Epoxide-III,IDT and T_g-DMA-DMA were improved by increasing the proportion of ERL-4221 and had maxima corresponding to simple anhydride curing ERL-4221,exceeding 24%and 51%.For chemical degradation of copolymerized products,we found that increasement of ERL-4221 influenced the degradation rates notably.The complete degradation time of the copolymerized product having 50%ERL-4221 would be100 times simple anhydride curing Epoxide-III.We also found that changing acidity and temperature could tune chemical degradation rates.All of the investigations proved that three cycloaliphatic epoxy resins containing acetal or ketal bonds could be applied according to practical requirements.