| SMC products can be well designed, simple process and high production efficiency. Thus they can be widely applied in all areas of the national economy. SMC is currently made of unsaturated polyester resin, but this SMC can not be used in some special conditions. Because it has some defects, such as temperature resistance, corrosion resistance, insulation and strength of structure is not very good. Now the glass fiber reinforced epoxy molding compound mainly used in electronic packaging, although it can be made sheet, but it based on the method of mixing. It is not used chemical thickening, and it is not a real sense of the epoxy sheet molding compound.The dissertation used diisocyanate and MgO thickening epoxy and conclude the thickening mechanism, moreover, it research the flowability of epoxy which has been thickened, in order to provide essential data and methods of thickening epoxy for the development of epoxy sheet molding compound.Firstly, several important factors affected the thickening characteristics of epoxy, such as the contents of thickening agents, the molecular weight of isocyanate prepolymer, temperatures, the ratio of solid epoxy resin, and through differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FTIR) concluded the thickening mechanism of epoxy. The results indicated that diisocyanate could thicken epoxy, with the amount of thickening agents increase, the molecular weight of diisocyanate prepolymer augment, temperature rise and the ratio of solid epoxy resin increase, the speed of thickening epoxy become quickly; the thickening mechanism is that the secondary hydroxyl groups of epoxy react with isocyanate group, molecule link up through carbamate and form mesh structure, so that the viscosity of epoxy system is increased.Secondly, it studied the contents of MgO, the contents of organic acids, temperature and the type of organic acid to the effect of thickening epoxy, and through Fourier transform infrared spectroscopy (FTIR) concluded the thickening mechanism of epoxy. The result indicated that MgO and a - methacrylic acid can together thicken epoxy, and the speed of thickening epoxy become quickly with the increasing content of MgO; when the ratio of MgO and a - methacrylic acid is 3:1, thickening epoxy have a better effect; the thickening mechanism: the terminal corboxyl group of a - methacrylic acid react with MgO, and it accompany with large numbers of heat, the heat can accelerate the reaction between the terminal corboxyl group with the secondary hydroxyl groups of epoxy, intermolecular hydrogen bonding which the water of above-mentioned formation result in and complex compound which format the metal atoms and carbonyl group complexing collective increase the viscosity of epoxy resin.Finally, it studied the heated flowability of thickened epoxy which used MgO and TDI, the speed of shutting mould and the viscosity of epoxy SMC on the effect of epoxy SMC flowability, and established mathematical model to describe the flowability of epoxy SMC in mould. The results indicated that epoxy resin which used TDI thickening has good heat flow; with the speed of shutting mould and the viscosity of epoxy SMC increasing, the deformation work which sheet material need is enhanced and the pressure of molding is increased.
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