Study On Synthesis And Chain-extended Modification Of Fluorene-based Epoxy Resin

Three fluorene-based monomers,9,9’-bis-(4-hydroxyphenyl)-fluorine (BHPF),9,9’-bis-(3-methyl-4-hydroxyphenyl)-fluorine (BMPF),9,9’-bis-(4-(2-hydroxyethoxy)phenyl)-fluorine (BHPEF), and a fluorenyl curing agents fluorene (BAOFL) were synthesized from9-fluorenone and phenol, alcohol or amine. Three fluorene-based epoxy resins were obtainedfrom BHPF, BMPF and BHPEF. The chemical structures of the products were characterizedby FT-IR,1H NMR and13C NMR analyses. BAOFL was obtained from BNOFL which wasfrom the reaction of9,9-bis-(4-hydroxyphenyl) fluorene and4-nitrochlorobenzene usingethanol as solvent. The influences of different catalysts on the yields of nitro reduction werediscussed. The yield of BAOFL was83.5%.The BHPEF and BAOFL curing processes and curing kinetics were confirmed by theDSC curves to calculate extrapolated curing temperature，and Eavalues were calculated byKissinger, Ozawa and Starink methods. The results of study shows: curing temperature of thedifferent curing systems exist the extremely differences. Kissinger and Starink methodsshowed good agreement with the experimental data, and Ozawa method showed the biggerrerults than the two formers.Fluorene-containing epoxy resin (DGEBF) exhibits the advantages of good thermalstability and low moisture absorption, however, the disadvantages of lower tenacity influencesprocessing properties. The tenacity could be ameliorated by drowing into the structure ofether bond in the main segments.Moreover, BAOFL was a novol curing agent which containsfluorenyl and etheric diamines, and cured with epoxy resins possess excellent thermal stabilityand low moisture absorption. The water uptake of cured DGEBF which in100℃boilingwater for72h was1.74%, and exhibits good processing properties due to the structure ofether bond.Chain-extended fluorene-containing epoxy resins were synthesized from bisphenolcompounds, the mechanical performance and thermal performance of chain-extendedfluorene-containing epoxy resin curing systems were studies by dynamic mechanical analyzer(DMA) and thermogravimetric analysis (TGA). The results of study shows: thermalperformance of cured resin systems which E-51was chain-extended by BHPF are the betterthan the neat E-51systems, and the glass-transition temperature (Tg) of cured resins systems redused following content of E-51. The thermal stability of E-51was modified throughchain-extended by BHPF; The storage modulus and Tgof cured resin systems which DGEBFwas chain-extended by bisphenol AF were sightly lower than the neat DGEBF, but processingperformance of cured resin systems were modified; A decrease in storage modulus whichDGEBF was chain-extended by bisphenol A were observed due to flexibilitied chain wasimported. Both Tgand char yield of bisphenol AF/DGEBF were higher than bisphenolA/DGEBF according to the thermal stability of fluorocarbon was better than hydrocarbon atthe same ratio.