Polymerization of Vinyl Monomers Initiated by Cobalt () Chloride

摘要

The polymerization of methyl methacrylate initiated by cobalt(￥±) chloride in tetrahydrofuran has been studied. The conversion was increased liearly with polymerization time at initial stage of 6?-7% conversion and then the rate of polymerization was slightly reduced, and after that the autoacceleration was observed. The rate of polymerization was increased with the concentration of cobalt(￥±) chloride, but at the concentration of cobalt(￥±) chloride higher than 3.4??10-4 mole/l the rate of polymerization was decreased. The rate of polymerization was dependent on the 1.38 power of the concentration of methyl methacrylate. The effect of the radical inhibitor DPPH was observed and the inhibition time was increased with the concentration of DPPH. The apparent overall activation energy was calculated to be 13.2 kcal/mole. In the copolymerization of methyl methacrylate (M1) and styrene (M2), the monomer reactivity ratio was found to be r1 = 2.35, r2 = 0.78. From the above results. the initiation mechanism of polymerization was discussed and it was considered that the polymerization proceeds mainly via diradical mechaism.