Study On The Synthesis,Cure And Application Of Liquid Crystalline Epoxy Resin

Compared with other ordinary epoxy resin, the liquid crystalline epoxy resin's capabilities of heat-resistant,water-resistant and impact-resistant are improved and the liquid crystalline epoxy resin are also prepared to high-powered composite material; Furthermore, liquid crystalline epoxy resin has not only a little linear expansion coefficient, but also a high dielectric strengh and low dielectric dissipation. Liquid crystalline epoxy resin can be used in electronic encapsulation domain of high-powered requirement. In this article, a novel liquid crystalline epoxy resin was synthesized, and curing behavior and mixed with bisphenol-A epoxy resin were investigated.1. The liquid crystalline epoxy resin-p-phenylene di{4-[2-(2,3-epoxypropyl) ethoxy]benzoate}(PEPEB) was synthesized from allyl 2-hydroxyethyl ether. Its structure and liquid crystalline behavior were characterized by FTIR, DSC, ~1H NMR, Polarizing microscope with a hot stage (POM) and X-ray diffractometer (XRD). The result show that the compound was thermotropic liquid crystalline polymer and have a nematic phase.2. The curing behavior of the Liquid crystalline epoxy resin (LCER) with 4,4-diaminodiphenylmethane(DDM) and 4,4-diamino-diphenyl ether(DDE) were studied by FTIR, DSC, TBA. Non-isothermal curing kinetics of systems were investigated by DSC. Morphology of curing product were observed by POM at different temperature. POM observation show that with the upgrade of initial curing temperature, the filament structure of this system transferred from anisotropy to isotropy.3. The mixture of PEPEB with bisphenol-A epoxy resin (BPAER) was cured with a cured agent of 4,4-diamino-diphenylmethane (DDM). The curing process and thermal behavior of this system were investigated by differential scanning calorimeter (DSC) and torsional braid analysis (TBA). The morphological Structure were measured by X-ray diffractometer (XRD), Polarizing optical microscope (POM) and scanning electron microscope (SEM). LC structure was fixed in the cured epoxy resin system. The impact strength and T_g of the system are increased than the common bisphenol-A epoxy resin, The curing kinetics was investigated by DSC.