| A basic material for copper clad laminates, diglycidyl ether of bisphenol-A (DGEBA) was synthesized through two-step method. The technological process which proved mature had been realized in industry and filled the vacancy of China. The effect of reaction conditions on total chloride content, epoxy equivalent weight, color, molecular weight and its distribution of products was investigated. The result showed that selecting raw materials of high quality, using nitrogen as protective gas during reaction, controlling the rate of sodium hydroxide addition, decreasing the pressure and the temperature while recycling epichlorohydrin and toluene, decreasing the time of high temperature reaction were preventive measures which benefit the color elimination of epoxy resin to some extents. The content of alkali in the first etherification is 50% of total content and the temperatures of etherification and ring-closing reaction are 90C,70C respectively, the synthetic DGEBA can meet the demand of copper clad laminates and the amount of by-product of high-molecular weight is the lowest.Reaction kinetics was studied by high performance liquid chromatography (HPLC) and the constant of reaction rate and the activation energy for each stage during the catalyzed etherification were calculated. It was found that the etherification of phenol hydroxyl groups was a second order reaction and the ring-closing reaction of chlorohydrin ether was a first order reaction.The cure kinetics of DGEBA / Dicyandiamide (DICY) system was investigated under temperature programming curing condition. Differential Scanning Calorimetry (DSC) was the thermo-analytical technique used to determine the cure kinetics of this system. The cure kinetic equations were deduced from Kissinger equation and Ozawa-Flynn-Wall equation. These mathematical techniques were used to evaluate the parameters of the cure kinetics, the reaction order and activation energy. The results show that both of the cure models are in a good agreement with the experimental data.A phosphorus-containing monomer, 10-(2, 5-bis(hydroxy) phenyl)-9. 10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DHPDOPO), was synthesized through 9, 1O-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) and 1, 4-benzoquinone. The structure of DHPDOPO was characterized by elemental analysis, Fourier transform infrared (FTIR) and 'H-NMR spectroscopies. The phosphorus-containing epoxy resins with phosphorus content of 1 wt % and 2 wt % were synthesized through DHPDOPO, bisphenol-A and a low molecular weighted diglycidyl ether of bisphenol-A. The structure, molecular weight and molecular weight distribution of two phosphorus-containing epoxy resins were confirmed by FTIR and gel permeation chromatography (GPC).Compositions of the phosphorous-containing epoxy resins with different curing agents, D1CY, Novolak, phenolic-melamine(PS-6313,PS-6333 developed by GUN El Chemical Industry Co., LTD. Japan), were studied to compare their thermal and flame properties with those corresponding compositions of the bromine-containing epoxy resins by DSC, thermal gravimetric analysis (TGA) and limiting oxygen index(LOI). The different curing agents were compared with each other at the same time. The results indicated that the phosphorous-containing epoxy resins exhibited better thermal properties and higher LO1 value as well as higher char yield than bromine-containing epoxy resins when the content of phosphorous is equal with that of bromine. The glass transition temperature(Tg) of cured epoxy resins decreased and the flame resistance increased with the increase in bromine content while Tg and the flame resistance increased with the increase in phosphorous content. The phosphorus-containing resins were cured by nitrogen-containing curing agents, the flame resistance of their compositions may be improved greatly. The effect of nitrogen to phosphorus is connected with the P/N ratio. It may exist a range in which the flame resistance of cured epoxy resins increased with the increase of the P/N ratio.For halogen-free poly...
|
PDF Full Text Request