Study On The Toughening Modification Of Epoxy Resin By Poly(Ester-amide)s

Epoxy resin is one of the most important thermosetting resins,which is widely used because of its excellent mechanical,electrical,chemical resistance and other properties.However,the brittleness of epoxy resin greatly limits its’ applications.So the research on toughening of epoxy resin has become the urgent affairs.In this paper,linear carboxyl-functionalized poly(ester-amide)s were synthesized by adipic acid,triethylene glycol/methyl propylene glycol,urea and maleic anhydride under a certain process.The poly(ester-amide)s were characterized by FT-IR and GPC.Results show that the synthesized polymer contain the ester group and ether linkage.Their molecular weight distributions were narrow,and molecular weight decreased with the increase of urea ratio.The process of poly(ester-amide)modifying epoxy resin was characterized by acid value test,epoxy value test and FT-IR.The results show that grafting reaction happened between terminal carboxyl of poly(ester-amide)and epoxy group of epoxy resin.When raw material mole ratio of adipic acid,triethylene glycol,urea and maleic anhydride was 10: 8: 2: 2,the poly(ester-amide)synthesized had the best effect of toughening epoxy resin.Under a certain curing process,when the mass ratio of the poly(ester-amide),epoxy resin E-44,methyl hexahydrophthalic anhydride,methyl nadic anhydride,pyridine is 10: 100: 35: 35: 0.47,the impact strength of cured epoxy modified by poly(ester-amide)was the highest,which reached 26.5 k J/m2,78.1 % higher than unmodified one.But the flexural strength was slightly decreased,at 118.7 MPa.Impact sections of cured epoxy resins were characterized by SEM,ductile fracture characteristic of modified one was obvious.And the observations agreed with the impact strength values measured.At the same time,curing rate of epoxy resin was slow down by introducing of poly(ester-amide)s.Thermal stability ofmodified epoxy was improved by linear poly(ester-amide).It can avoid the decrease of thermal stability of epoxy resin when it was modified by hyperbranched poly(ester-amide)s.Linear poly(ester-amide)s toughening epoxy resins have potential application values.