PurposeThe purpose of this paper is to synthesise high‐purity 9,9‐bis(4‐hydroxyphenyl)‐fluorene (BHPF).Design/methodology/approach9,9‐bis(4‐hydroxyphenyl)‐fluorene was prepared from phenol and fluorenone using cationic ion‐exchange resin as the condensation catalyst. The purity and chemical structure of the resulting 9,9‐bis(4‐hydroxyphenyl)‐fluorene were characterised by elemental analysis, MS, HPLC, FTIR, 1H NMR and 13C NMR spectroscopy, etc.FindingsThe purity and weight yield of 9,9‐bis(4‐hydroxyphenyl)‐fluorene reached up to 99.1 and 81.3 per cent, respectively, under the optimal reaction condition, that is, the molar ratio of phenol to fluorenone was 8‐1, the reaction temperature was 100°C, reaction time was 10 h, the mass percentage of cation exchanger accounting for the total reactants was 15 per cent and the co‐catalyst quantity was 0.2 ml.Originality/valueThe method for preparation was novel and could find numerous applications as monomer or modifier for heat‐resistant adhesives, high‐temperature coatings and matrix resin for advanced composites, etc.
Diglycidyl ether of bisphenol fluorene (DGEBF) and 9,9-bis(4-aminophenyl) fluorene (BPF) were synthesized to introduce more aromatic structures into an epoxy system, and their chemical structures were characterized with Fourier transform infrared spectroscopy, NMR, and mass spectrometric analysis. The dynamic curing behavior of the DGEBF/BPF system was investigated with differential scanning calorimetry. DGEBF was cured with BPF, diaminodiphenylsulfone (DDS), and diaminodiphenylmethane (DDM), and E-44 (bisphenol A epoxide) was also cured with BPF for comparison. The thermal properties of the obtained polymers were evaluated with dynamic mechanical thermal analysis and thermogravimetric analysis. The cured DGEBF/BPF system showed a remarkably higher glass-transition temperature, better thermal stability and lower moisture absorption in comparison with the general bisphenol A epoxy resin/BPF system but approximated the heat resistance of the DGEBF/DDS and DGEBF/DDM systems. Such properties make this epoxy system very promising for heat-resistant applications.
PurposeThe paper's purpose is to optimise lab‐size synthesis process of a fluorene‐containing epoxy resin, characterise structure of the resulting epoxy resin and evaluate mechanical properties of the cured fluorene‐containing polymers.Design/methodology/approachThe synthesis of the fluorene‐containing epoxy resin was accomplished by the polycondensation of 9,9‐bis(4‐hydroxyphenyl)‐fluorene and epichlorohydrin in the presence of quaternary ammonium salt and composite solvent under vacuum. The chemical structure of epoxy resin thus obtained was characterised with FTIR, NMR and MS. The shear strengthes of cured fluorene‐containing epoxy resin were determined and compared with that of cured E‐44 bisphenol A epoxy resin and F‐44 novolac epoxy.FindingsThe epoxide equivalent weight (EEW) of the fluorene‐containing epoxy resin reached 240‐246 g/mol under optimal epoxidising condition. The resulting epoxy resin exhibited approximate high temperature performance relative to F‐44 novolac epoxy, much better heat resistance than that of E‐44 epoxy resin and lower moisture uptake than that of the two above‐described resins.Research limitations/implicationsThe shear strength of cured fluorene‐containing epoxy resin was relatively low at ambient temperature, whereas was much higher than that of bisphenol A epoxy resin at higher temperature, making it a potential candidate for many applications such as high temperature adhesives, coatings and matrix resins for advanced composite.Originality/valueThe method for preparation was modified and improved, structure characterisation was comprehensive. The material prepared could find numerous applications as heat‐resistant adhesives and matrix resins.
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