AbstractIn the first of a two‐part series, a kinetic study has been made on the effects of gamma rays (60Co) in air and inert gas on the polymerization of a 50:50 weight‐mixture methyl methacrylate (MMA)–kaolin clay system. The effect of dose rate (7.35–24.9 rads/sec), temperature (25° to 75°C), and total dose on the percentage conversion of monomer to polymer was studied. The rate of formation of polymer at 25°C in the composite system was found to be faster when compared to a bulk MMA system at the same dose rate. This acceleration showed that the clay had a catalytic effect on the formation of polymer. The effect decreased as temperature increased. Two types of poly(methyl methacrylate) (PMMA) were formed in the composite. One type was called homopolymer and could be removed from the composite by extraction with organic solvents. The other type was called inserted polymer and could only be removed by dissolving the clay matrix with hydrofluoric acid. The total polymer conversion was the summation of these two types of polymer formed. The kinetic analysis examined the orders of reaction and activation energies of the homopolymer, inserted polymer, and total polymer. The initial reaction orders of the homopolymer and total polymer based on dose were −0.46 and −0.49, respectively. These indicate a definite free‐radical reaction. The reaction order of the inserted polymer was temperature dependent.The activation energies for the homopolymer and total polymer in both atmospheres were approximately 1 kcal/mole less than the bulk activation energy at the same conditions. The inserted polymer had an activation energy which was dos
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