A study of the kinetics of polymerization of polyester-acrylates by electrical conductivity measurements infrared spectroscopy and viscometry☆

A NUMBER of papers have been published recently in which electrical conductivity measurements have been used for the study of bulk polymerization [1-3]. This is possible because the specific volume resistances (Pv) of the starting materials and of the polymerization products differ substantially. The literature still contains no quantitative data on the relationship between A, and the degree of conversion of the polymeri~n~ substance. The establishment of this relationship is of prime importance to the problem of the applicability of the electrical conductivity method to the study of polymerization I~Jnetics. An attempt was made in the present work to obtain the requisite data. For this purpose the change in PB during polymerization was compared with results on the course of the process obtained from determination of the C----C unsaturated bends responsible for polymerization, and also with viscosity measurements. The material chosen for study was technically pure (bis-triethylene glycol)phthalate dimethacrylate, produced industrially under the code MGF-9. The use of the electrical conductivity method for study of the poly-,erization kinetics of compounds such as the polyester-acrylates is of particular interest because the insoluble, cross|inl~ed products formed complicate the use of the usual methods [4, 5]. The initiator used for room-temperature polymerization was the redox system consisting of 5% of isopropylbenzene hydroperoxide and 7% of cobalt naphthenate. The latter was used in the form of an 8% solution in methyl methacrylate. In experiments at 75, 80, 85 and 90 ° initiation was brought about by 0.5% of benzoyl peroxide added in the form of a 10% solution in methyl methacrylate