Heat effects for free-radical polymerization in glass ampoule reactors

Herein is reported an experimental study to evaluate the level of temperature control during bulk free-radical polymerization of methyl methacrylate/ethylene glycol dimethacrylate in ampoule reactors of various sizes at various temperatures, initiator levels and for two heat transfer fluids (water and silicone oil). This monomer system was chosen because of the pronounced autoacceleration in polymerization rate that it experiences. Five ampoule diameters (3, 4, 5, 7 and 10 mm outside diameter, Pyrex glass), four temperatures (60, 70, 80 and 90°C) and five initiator levels (0.1, 0.3, 0.5, 1.0 and 2.5 wt% 2,2′-azobisisobutyronitrile) were investigated. Polymerization conditions and reactor size under which near-isothermal polymerizations during autoacceleration may be followed using glass ampoule reactors are presented.