Bulk polymerization process

Dissimilar to general monomers, acrylates and methacrylates of hydroxy-(lower alkyls) and epoxy-(lower alkyls) can be polymerized quite rapidly at a low temperature ranging from the GTP (glass transition point) of the monomer to a temperature 1000C higher by the action of radiation (visible or UV radiation of 7000 to 1900 A or various ionizing radiations having a dose rate of 103 to 109 r/h and a dose of 103 to 108 r), in so far as the monomer is in a stable, supercooled, high-viscous, semisolid state. Rate of the polymerization is nearly proportional to the first power of the radiation dose, exhibiting a maximum at a temperature 500C higher than the GTP of the monomer. This process is advantageous in enabling readily controllable bulk polymerization with a very small volume contraction, and is successfully applicable to mold polymerization and laminate (GTP -960C), placed in an N2-flushed Dewar vessel (-480C), was irradiated with Co 60 gamma rays at a dose rate of 1 x 105 r/h for 40 minutes. Polymer yield was 95.7%. The product was colorless, insoluble in most organic solvents, and had high mechanical strength. At 1400C it softened but did not flow, above which it gradually hardened. Even at 2000C it showed no deformation. (Kaichi, S.)