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Keywords:

  • fluorinated epoxy resins;
  • dielectric properties;
  • thermal stability

Abstract

A novel fluorinated epoxy compound, 4,4′-bis(2,3-epoxypropoxy-phenyl)-1-(3-trifluoromethylphenyl)-2,2,2-trifluoroethane (BEF), was synthesized starting from the coupling of phenol with 3′-trifluoromethyl-2,2,2-trifluroacetophenone catalyzed by Lewis acid to yield an intermediate compound, which was then converted to the fluorinated epoxy by epoxidation with epichlorohydrin. BEF could be thermally cured with organic anhydride or aromatic amine as curing agents to produce thermally cured epoxy resins. Experimental results demonstrated that the thermally cured fluorinated epoxy resins showed good thermal stability with decomposition temperature at 5% weight loss of 342–364°C in nitrogen, high glass transition temperature (Tg) of 165–171°C (determined by DMA), and outstanding mechanical properties with flexural strengths of 79–119 MPa, flexural moduli of 2085–2130 MPa. The thermally cured fluorinated epoxy resins also exhibited excellent electric insulating properties with volume resistivity of 1.59–9.23 × 1016 Ω cm and surface resistivity of 4.81 × 1015–7.70 × 1016 Ω. The dielectric constants at 1 MHz were measured in the range of 3.1–3.4 and the dielectric dissipation factor (tan δ) in the range of 1.38–2.48 × 10−3. It was found that the fluorinated epoxy resins have improved electric insulating and dielectric properties as well as lower moisture adsorption compared with the corresponding commercial Bisphenol A type epoxy resins. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011