四氟乙烯/偏氟乙烯/全氟甲基乙烯基醚乳液共聚合反应动力学

Emulsion Copolymerization Kinetics of Gaseous Monomers Containing Fluorine

对气相含氟单体四氟乙烯 ( TFE) /偏氟乙烯 ( VDF) /全氟甲基乙烯基醚 ( PMVE)的乳液共聚反应动力学进行了研究。实验结果表明 ,搅拌速率对共聚反应速率有较大影响 ,搅拌速率在550 r/ min～ 850 r/ min范围内反应速率随搅拌速率增加而增大 ;当搅拌速率大于 850 r/ min时 ,反应速率随搅拌速率的变化趋缓。实验测得 60°C下该三元乳液共聚合反应速率对初始乳化剂浓度、初始引发剂浓度和反应总压力分别呈 0 .0 58级、0 .40 6级和 1 .540级反应 ,由此推导得乳液共聚合的反应速率表达式为 rp=k S0 .0 58I0 .4 0 6p1.54 0 ,其中速率常数 k为 5.78× 1 0 -3 g-0 .4 64 · dm1.3 92 ·( MPa) -0 .54 0·min-1。

The emulsion copolymerization kinetic of tetrafluoroethene (TFE)/vinylidene fluoride(VDF)/perfluoromethyl vinyl ether(PMVE) was studied and the copolymerization rate was measured according to the pressure of reaction system. The experiment results show that the TFE/VDF/PMVE emulsion copolymerization exhibits different kinetic behavior compared with Smith Ewart theory. The emulsion copolymerization rates of TFE/VDF/MVE are sensitive to stirring rates as these gaseous monomers need high stirring rate to eliminate the diffusion effect of such monomers from gaseous phase to liquid phase. It is found that when the stirring rate blow 550r/min, the copolymerization rate of TFE/VDF/PMVE is very slow; while the stirring rate between 550r/min to 850r/min, the copolymerization rate is less influenced by the stirring rate. The emulsion copolymerization rate for such a system is proportional to the 0.0580 power of the concentration of emulsifer ( S ). It is also found that the emulsion copolymerization rate of TFE/VDF/PMVE is proportional to the 0.406 and 1.54 power to the initial initiator concentration( I ) and the total gaseous pressure of the reaction system ( p ) respectively. At high enough stirring rate, the emulsion copolymerization rate of TFE/VDF/PMVE at 60°C is mainly determined with initial S, I and p , and can be expressed as r p=5.78×10 -3 S 0.058 I 0.406 p 1.540 .