Abstract: Based on the possible propagation reaction of 8,9-benzo-2-methylene-1, 4,6-trioxaspiro [4,4] nonane (Ⅰ), initiated by free radical initiators, a kinetic equation has been deduced. The rates of monomer(Ⅰ) Consumption and phthalide formation during the polymerization were measured by IRand the experimental results confirmed the kinetic equation. This demonstrates that the propagation reactions of monomer (Ⅰ) include two reactions addition polymerization and ring-opening -isomerization-addition polymerization. The relative contribution of these two reactions to the total polymerization rate depends on the monomer concentrations. The structure of polymer is measured.

Key words: 8,9-Benzo-2-methylene-1,4,6-trioxaspiro[4,4]nonane, IR spec-trometry, Kinetic method, Propagation mechanism