Effect of ultrasonic separation on the structure and properties of diallyl phthalate prepolymer

The bulk polymerization of diallyl phthalate (DAP) was carried out at high temperature (190 °C) without using any initiator, and the reaction was stopped before the gelation point in order to get the prepolymer of DAP. The mixture for the prepolymer and the monomer was successfully separated by a novel ultrasonic method for the first time, and the separation efficiency for the new method was obviously higher than that for the traditional reprecipitation. The product obtained by ultrasonic separation was characterized by infrared spectroscopy (IR), gel permeation chromatography (GPC) and iodine number measurement. It was shown that the average molecular weight of the prepolymer got by the ultrasonic method was lower than that of the prepolymer got by the multi-precipitation, moreover, the molecular weight distribution of the prepolymer got by the ultrasonic separation was broader. Besides, the residual unsaturation degree of the prepolymer separated by ultrasonic was slightly higher than that of prepolymer separated by reprecipitation.