AbstractRadical polymerization of monoallyl phthalate (MAP) was conducted at 70, 80, and 90°C, benzoyl peroxide being used as an initiator. It was found that the analytical values of the polymer obtained were always lower than the calculated ones for MAP homopolymer and nearly constant regardless of the polymerization conditions. From the detailed investigation it was concluded that the results are due to the formation of polymer including about 20 mole % of allyl alcohol units; such allyl alcohol units might be incorporated into the polymer through propagation accompanied by partial elimination of phthalic anhydride