ON THE POLYMERIZATION OF VINYLIDENE FLUORIDE UNDER THE INFLUENCE OF $gamma$- IRRADIATION

Radioinduced polymerization in bulk of vinylidene fluoride was investigated and the results compared with previous studies carried out with tetrafluoroethyiene and trifluorochlorethylene. The rate of radiative polymerization under the same conditions is tetrafluoroethylene > vinylidene fluoride > trifluorochlorethylene and the corresponding yields per 100 ev are 10/ sup 6/, 10/sup 5/, and 10/sup 4/ molecules, respectively. Polymerization occurs in all cases with a high conversion rate, practically up to 100%. A considerable induction period, effected by impurities (especially oxygen), was observed and, therefore, the monomer was purified before use. The latter was a commercial grade of 99.8% purity. The dependence of the conversion upon irradiation time was studied at 23 deg C with doses of 1, 5, 10, and 30 rad/ sec and the rate of reaction determined from the inclination of the kinetic curves. The value of the radiation-chemical yield decreases with the dose capacity. An increase in temperature raises the rate of the radiation polymerization, but for all investigated temperatures (-78, -20, 0, 23 deg C at 10 rad/sec) a maximum value was obtained after about 6 hr. The total activation energy of radiative vinylidene fluoride polymerization was determined with 3.6 kcal/mole. The process occurs by a radical-chainmore » mechanism. (OTS)« less