| Abstract: | Styrene was polymerized in emulsion with initiation by γ-rays at a dose rate of 0.6 Mrad/hr. Polymerization rates were as expected from previous reports by others. No branching or crosslinking was detectable, and the M w/M n ratio of the polystyrene did not change significantly during the course of the polymerization reaction. The molecular weight of the product polymer decreased with increasing conversion, in contrast to the behavior of chemically initiated emulsion polymerizations. Monomer-free polystyrene does not degrade under the same radiation conditions, and the progressive decrease of polymer molecular weight with conversion is shown to result from the presence of monomer. |
