The polymerization of diallyl phthalate, an investigation by infrared spectroscopy

The changes in relative unsaturation of the monomer‐polymer system of diallyl phthalate have been studied by means of the infrared absorption hand at 1645 cm.‐1 over the temperature range of 60‐120° both before and after gelation. It was found that the initial reaction can be described in terms of second‐order kineties with an activation energy of 15,900 cal./mole. Relationships have been derived for (a) the dependence of the relative unsaturation u/u0 on the degree of conversion α, and (b) the relationship among α, time, temperature, and catalyst concentration. The value of α at the critical point determined in the above manner is in good agreement with the theory but appears to he temperature‐dependent; possible reasons for this dependency are given. It is pointed out that the infrared technique is a suitable method for study of post‐gelation kinetics and polymer structure.