| Abstract: | Depolarization currents were used to study the persistent polarization induced in polystyrene and poly(methyl methacrylate) by cooling with flow under pressure. These studies showed that the charge on electrets made by flow under pressure consists in part of a surface charge which leaks off rapidly in moist air and in part of a charge due to volume polarization which decays more slowly. The volume polymerization produced in poly(methyl methacrylate) by flow under pressure is of the same order as that produced by cooling under a voltage drop, but flow under pressure produces a larger surface charge. |
