Polymerization Of Concentrated Emulsion Assisted By Microwave Irradiation

In microwave chemistry, the studies on complex permittivities of organic reagents in microwave frequency were few reported, which has resulted in much difficulties for the mechanism analysis. In our study, the permittivities of 32 kinds of organic reagents were determined at frequency 2.45 GHz and 3.0GHz by using microwave cavity perturbation method. Basing on these measurements, we discuss the relationship between material permittivity and its molecular structure. In the permittivity measurement of binary mixture system, it is found that some certain mixture system has larger value than its single component in imaginary part, even real part of permittivity. This phenomena has not been reported, and it reveals that a proper mixture system can increase the microwave dispersion property of material. This can help us to determine the proper condition for a reaction assisted by microwave irradiation.The key factor of the concentrated emulsion is the stability. In this study, the influence factors include monomer, emulsifier and the viscosity of the continuous phase were investigated. The results showed that the stability of the concentrated emulsion could be mostly affected by the polarity of monomers, and the stabihty increased by using multi-emulsifiers.The concentrated emulsion polymerization of styrene assisted by microwave was studied in this paper. Lauryl sodium sulfate (SDS) and Polyoxyethylene (10) octylphenyl ether (OP-10) were used as mixed emulsifiers to obtain stable concentrated emulsion system. The polymerization was conducted using convection heating and microwave irradiation. The results showed that the polymerization could be assisted by microwave. For a 3h reaction at 50℃, the conversion of styrene was about 30% for heat polymerization and 60% for a 50w microwave irradiation. The polymerization rate could be greatly improved by increasing microwave power. The conversion of styrene could achieve 64% in 5min during a 480w microwave irradiation, but the stability of emulsion was damaged. The GPC analysis showed that the polystyrene obtained in 3h reaction have similar average molecular weight (M_n=1.4×l0~6) and coefficient of MW...