Modification Of Epoxy Resin With Hydroxy Polyimide And Study On Curing Reaction Kinetics Of The Modified Resin System

Epoxy adhesive is the main kind of structural adhesive,and it has an excellent performance such as low shrinkage,electrical insulation properties,mixing performance and so on.However, because of their low extension,brittleness,it is not appropriate to use in structural parts,the brittleness of epoxy curing material greatly restrict its application.Polyimides(PI) especially aromatic polyimides have excellent properties of resistance to abrasion,thermal stability,radiation resistance,high dimensional stability.But pure PI have shortcomings of poor adhesion,higher processing temperatures and so on.Modified epoxy resin with PI can integrate the advantage of epoxy adhesive and PI,which has good thermal stability and adhesion.Polyimide containing phenolic hydroxyl has high glass transition temperature and excellent thermal stability,and as a result of the existence of phenolic hydroxyl groups,it can react with epoxy group and form a covalent bond,thereby it can enhancing the compatibility of the two and get a good toughening effect.This article mainly contains five parts:(1) preparation of the the momomer of hydroxyl polyimide(2)synthesis and performance test of a series of hydroxyl polyimide films(3) synthesis and performance test of hydroxyl polyimide powder(4) preperation and performance test of epoxy resin modified with hydroxyl polyimide(5)study on the curing reaction kinetics of epoxy resin modified with hydroxyl polyimide.3,3'-diamino-4,4'-dihydroxybiphenyl was prepared in this article,whose melt point was 335.2℃.A seies of polyimide films was prepared by 3,3'-diamino-4,4'- dihydroxy biphenyl(DADHBP),2,2-bis-[4-(4-aminophenoxy)phenyl]propane(BAPOPP) and 3,3',4,4'-tetracarboxy-licdiphenyl ether dianhydride(ODPA) with different ratios in the presence of dimethylacetamide(DMAC) as the solvent.The tests of DSC,TGA,FT-IR,UV-visible transmittance,contacting angle,water absorbance and machanical performance were performed on the seies of polyimide films.The results showed that the PI film whose monomer ratio (DADHBP:BAPOPP:ODPA) of 1:3:4 had the best overall performance.The hydroxyl polyimide powder was synthesized from an consendation reaction with 3,3'-diamino-4,4'- dihydroxy biphenyl(DADHBP),2,2-bis-[4-(4-aminophenoxy)phenyl]propane(BAPOPP),4,4'-dianimo -diphenyl aehter,3,3',4,4'-tetracarboxy-licdiphenyl ether dianhydride(ODPA) and 3,3',4,4'-benzophenone tetra boxylic dianyhydride(BTDA).The tests of DSC,TGA,FT-IR,were performed on the hydroxyl polyimide powder.The adhesive was prepared by this PI mixed with TGDDM and ES216 epoxy resin respectively,on which the tests of tensile strength,gel time and TGA were performed.The results showed that ES216 epoxy resin had good themal performance. The temperature of its weight loss of 5%was 387℃,and its tensile strength was 13.6MPa。A study on curing reaction kinetics of ES216 epoxy resin was also carried out.The curing process were studied by the non-isothermal differential scanning calorimeter(DSC),and the kinetics of the curing processes were analyzed by Kissinger,Crane and Arrhenius equations.Curing kinetics parameters were evaluated.The results showed that the activation energy and the order of reaction of the system were 69.97kJ/mol and 0.902.