Synthesis And Application Study Of Ester-containing Fluorene Diamine

In this paper, two kinds of ester-containing fluorene diamine and six kinds ofbenzoxazine monomers were synthesized. The structures of monomers were identified viaFourier transform infrared (FT-IR), proton and carbon nuclear magnetic resonances (1H NMRand13C NMR). The polymerization behavior, mechanical property, and thermal stability ofbenzoxazine were measured using differential scanning calorimetry (DSC), dynamicthemomechanical analyzer (DMA), FT-IR, and thermogravimetric analysis (TGA).First,9,9-bis(hydromethyl) fluorine (BHMF) was prepared through method ofhydromethylation using fluorene as raw material. Second,9,9-bis(4-nitrobenzoic acid methylester) fluorene (BNBMF) and9,9-bis(4-nitrobenzoic acid-4-phenyl ester) fluorene (BNBPF)were synthesized through the reaction of4-Nitrobenzoyl chloride with BHMF andBHPF respectively. And then two kinds of new ester-containing fluorene diamine(BABMFand BABPF) monomers were obtained by catalytic hydrogenation of the dinitro compoundusing hydrazine hydrate and Pd/C catalyst in refluxing ethanol.As curing agent, BABMF and BABPF were cured with several different epoxy resinincluding TDE-85, E-51, fluorene based epoxy resin(DGEBF) and DGEBF/E-51, respectively.The BABMF and BABPF curing processes and curing kinetics were confirmed by the DSCcurves to calculate extrapolated curing temperature. The mechanical property and thermalstability of epoxy resins were measured using dynamic themomechanical analyzer (DMA)and thermogravimetric analysis (TGA). The results shows that: BABMF and BABPF systemhave similar regularity in the mechanical and thermal properties. In terms of Tg, DGEBF hasthe highest Tg, then DGEBF/E-51, the third TDE-85,the lowest is E-51, the TgofBABPF/DGEBF is as high as264℃. And DGEBF has the highest char yield (Yc) at800℃,then DGEBF/E-51.Six benzoxazine monomers which contain ester and fluorene were synthesized usingBABMF or BABPF, paraformaldehyde, and phenols including phenol, m-cresol and3-methoxyphenol as starting materials by Mannich condensation reaction. The results shows:the thermal properties of polymers were not significantly cut down after introduce ester intomonomers. In both BABMF and BABPF curing system, the T5value’s order is as follows:phenol>m-cresol>3-methoxyphenol, the Yc(800℃) value’s order is as follows: 3-methoxyphenol>phenol> m-cresol, and the Tgof3-methoxyphenol is also higher than theother two kinds of polymer. The Tgof BABPF-3-MOP-BOZ is243.44℃. The char yield at800℃of BABPF-3-MOP-BOZ is as high as50.78%.