The free radical initiated polymerization of diethylfumarate

The kinetics of polymerization of diethylfumarate initiated by 1,1′ azo-bis-isobutyronitrile have been studied at temperatures between 60 and 80°. Difficulty in isolating the polymer was overcome by using a petroleum ether-methanol two-phase system to separate the monomer and polymer, and by precipitating the polymer from the methanol phase with an aqueous salt solution. The density of the polymer varied from 1·183 g/cm³ at 80° to 1·211 g/cm³ at 20°, giving volume contractions of approximately 16 per cent for complete conversion of monomer into polymer. The initiator exponent was about 0·45, i.e. slightly lower than normally obtained from free radical initiated vinyl polymerization. The overall energy of activation for the polymerization was 89 ± 2 kJ/mole. Constants for chain transfer with monomer, determined from rate and molecular weight measurements at 60, 70 and 80, were in the region of 0·005 0·017.