| Tetrafunctional peroxide is a new type of initiator for free radical polymerization. The polymerization process initiated by tetrafunctional initiator is more complex since there are more than one active group in it. Polyether poly-t-butylperoxy carbonate (JWEB50) with four peroxide groups was investigated in this paper. Firstly, bulk free radical polymerization of styrene (St) initiated by JWEB50 was studied. The decomposition kinetics of JWEB50 and the detailed kinetics of polymerization kinetics were studied experimentally. Secondly, the model of polymerization rate was established based on the hypothesis of identical decomposition kinetics of the four functional groups in JWEB50. Thirdly, the synthesis of high impact polystyrene (HIPS) with the usage of JWEB50 was investigated, which would provide a theory direction for the application of this initiator in the industrial process of HIPS.Bulk free radical polymerization of St initiated by JWEB50 was studied, compared with its monofunctional counterpart tert-butyl (2-ethylhexyl) monoperoxycarbonate (TBEC). At equal molar concentrations of O-O group, it is shown that the kinetic curves of polymerization with JWEB50 and TBEC completely overlapped, which suggest that the concentrations of total free radicals for both initiators keep equal to each other during the polymerization. The existence of the O-O group in polystyrene (PS) molecular prepared with JWEB50 was determined by DSC.O-O group in the PS molecular obtained at different monomer conversions decomposited at the same temperature of about 165℃. And the concentration of O-O group in PS molecular decreased with the monomer conversion. Hence, the decomposition kinetic character of JWEB50 is similar with its counterpart TBEC and the hypothesis of identical decomposition kinetics of the four functional groups in JWEB50 was put forwards.At equal molar concentrations of O-O group, the polymerization rates were equal for these two initiators. However, the molecular weights of obtained polymer were higher for JWEB50 and such molecular-weight-increasing effect of JWBE50 was more pronounced at high temperature. When the initiator concentrations were the same, the molecular weights were higher for PS prepared by TBEC than the one by JWEB50.The effect of the polymerization temperature and concentration of O-O group on the polymerization rate of bulk free radical polymerization of St with JWEB50 were discussed through the dilatometers method. The polymerization rate would increase 2-2.5 times when the polymerization temperature increases 10℃. And it is proportional to the square of the concentration of O-O group.A kinetic model for polymerization rate of St was established based on the hypothesis of equal reactivity, long chain assumption and under the quasi steady state. The efficiency factor (f) was estimated by dilatometers method. The calculation results were in fairly good agreement with experimental data.The synthesis of HIPS with the usage of JWEB50 was investigated. The performance of JWEB50 was compared with TBEC. It was shown that the polymerization kinetic curves completely overlapped at the same temperature when the molar concentrations of O-O group were equal for these two initiators. Hence, the higher molecular weight and the equal polymerization rate could be obtained simultaneously by tetrafuctional JWEB50 compared to monofuctional TBEC at the same conditions. The effect of the temperature on molecular weights of HIPS prepared with JWEB50 or TBEC was investigated. It suggested that the molecular weight of obtained polymer changed slower with the increase of temperature for JWEB50, compared to TBEC. It meant that the molecular weight-increasing effect of JWBE50 would be more pronounced at high temperatures.The effect of the initiator type on the graft efficiency was also studied. At the same molar concentration of initiator, it was found that the graft efficiency was dramatically improved with the usage of JWEB50. And the evolutions of the viscosity during the preparation of HIPS recorded on-line by rotation rheometer (HAAKE RS6000) were very similar for these two initiators when the molar concentrations of O-O group were equal. The two viscosity verses time curves completely overlapped with each other. And the phase inversion region was determined by the change of viscosity of polymerization system and TEM, respectively. It turned out to be a flat in the viscosity curves. The phase inversion flats for the preparation process of HIPS with JWEB50 and PB were found to be occurred at a monomer conversion range around 15%-26%. Finally, the evolution of the morphology of HIPS particle was observed by TEM. It was found the morphology and the size of HIPS particle with JWEB50 kept constant after the phase inversion. |
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