Synthesis And Properties Of Novel Heat Resistant、Halogen-free Flame Retardant Epoxy Resin

With the development of the electronics and Pb-absent solder, the conventional epoxyresins are unable to satisfy some applications, which require higher thermal resistant, betterflame retardant and lower moisture absorption. Thus, it is necessary to design and develophigh thermal resistant, good flame retardant and low moisture absorption epoxy resinsystems for these applications.A novel epoxy resin and two novel types of curing agents were synthesized. Theproperties of the cured polymers were investigated by several methods. The relationship ofthese properties of the cured polymers with the structure of the epoxy resins or curingagents were studied.A novel epoxy curing agent containing both imide and dicyclopentadiene (DCPD)moieties were prepared. The curing reaction of this new curing agent with o-cresolformaldehyde novoloc epoxy (CNE) was investigated by non-isothermal differentialscaning calorimetry (DSC). The thermal properties of cured polymers were evaluated withthermogravimetric analysis (TGA). The epoxy resins exhibited good thermal stability. Inaddition, this new curing agent with CNE showed low moisture absorptions because of thehydrophobic nature of DCPD structure.Through the reaction between P-H group and the double bond group, DOPO wasincorporated into Poly(HPM-co-DCPD). A series of phosphorus-containing polymers (P-poly(HPM-co-DCPD)s) were synthesized and used as curing agents for preparing flameretardance epoxy resins. Thermal properties and flame retardant properties of the curedepoxy resins were investigated by TGA and the limiting oxygen index (LOI) test. The P-poly(HPM-co-DCPD)s cured epoxy resins exhibited good thermal stability. The limitingoxygen index values were found to certificate good flame retardancy of the cured resins.Furthermore, the inclusion of DOPO ring into the epoxy system reduced water absorptionof the cured resins due to the rigid hydrophobic structure of DOPO.The novel p-phenylphenol-4,4’-biphenyl epoxy resin (BPE) was synthesized througha two-step procedure. Firstly, p-phenylphenol-4,4’-biphenyl novolac resin (BPN) wassynthesized through4，4’-bis(methoxy-methyl)biphenyl and p-phenyl phenol. Then, BPEwas prepared via epoxidation of BPN with epichlorohydrin(ECH). The structure of BPEwas determined by several methologies such as FTIR spectroscopy,1H NMR spectroscopyand epoxide equivalent. A reactive phosphorus-containing compound (ODOPB) startingfrom DOPO and p-benzoquinone was successfully synthesized. The compound (ODOPB)was used as a reactive flame-retardant by an advanced reaction with BPE at various stoichiometric ratios to produce a series of phosphorus-containing epoxy resins. O-cresolformaldehyde novolac resin was used as curing agent. Thermal properties and flameretardant properties of the cured epoxy resins were investigated by TGA and the limitingoxygen index(LOI). The cured polymers exhibited great improvement in flame retardancy(LOI≥32). The epoxy resins exhibited good thermal stability and low water absorptions.