Study On Synthesis Of Hyperbranched Polyaryletherketone Bearing Pendant Carboxyl Group And Its Modified Epoxy Resin

Epoxy resins are one of the most important traditional thermosetting resins,and are widely used in aeronautics,coatings,adhesives due to their excellent properties such as good adhesion to various substrates,insulation performance,mechanical properties.However,the highly crosslinked structure make these materials prone to brittleness and to have poor crack resistance and low fracture toughness,which limited the application in high-tech fields.For this purpose,in this work,a series of hyperbranched polyaryletherketone bearing pendant carboxyl group were synthesized and used to modify the diglycidyl ether of bisphenol-A epoxy resin.Main contents and conclusions of the dissertation are presented as follows:(1)Hyperbranched poly(aryl ether ketone)(HBPAEK)was newly synthesized by our group from bis(4-fluorophenyl)ketone,m-trihydroxybenzene and carboxyl-containing bisphenol monomer phenolphthalin.We increase the proportion of m-trihydroxybenzene / phenolphthalin,three kinds of hyperbranched poly(aryl ether ketone)(HBPAEK)obtained.The samples thus obtained are referred to HBPAEK-5,HBPAEK-10,HBPAEK-15,respectively.The XRD result revealed that the resultant products were amorphous.The differential scanning calorimetry(DSC)revealed that the glass transition temperatures(Tg)were in the range from 186 to 201 ?,and the values decreased with the charged content of m-trihydroxybenzene.Moreover,the temperatures at 5% thermal weight loss suppassed 431?,and the residual weights at 700 ? were over 50%.(2)The DSC result demonstrated that the curing process of the HBPAEK modified epoxy resin system was determined to be 140?/2h+160?/2h+190??After that,the curing kinetics of the three HBPAEK modified epoxy resin was studied by Kissinger method,the activation energy of the HBPAEK-15 was lower than that of the linear sample by 13.1%.(3)The mechanical properties,thermal properties,and morphology of the epoxy systems modified with three HBPAEK-5,HBPAEK-10,HBPAEK-15 were examined.It was found that the flexural strength,flexural modulus,flexural strain at break,fracture toughness(KIC)and fracture energy(GIC)show a increasing trend.The five parameters were enhanced by 61.1%,20.7%,84.8%,32.1%,47.8%,respectively when compared with the linear sample modified epoxy resin system.Finaly,the fracture surfaces of the modified epoxy resins were subjected to scanning electron microscopy observation.It was found that compared with the linear polyaryletherketone,the fracture surface of the HBPAEK-15 modified epoxy resin was more rough and highly deformed,indicating the nature of the ductile fracure.