Dielectric study of side‐group rotation of methyl methacrylate in copolymers

The dielectric absorption due to the side‐group rotation of the methyl methacrylate (MMA) unit in MMA‐styrene and MMA‐p‐chlorostyrene (pCS) copolymers was measured. The relaxation time for MMA‐pCS copolymers with low MMA contents could be interpreted quantitatively in terms of the Kramers rate‐constant theory at the low‐friction limit. On the other hand, the frictional effect on the relaxation time could not be ignored for any copolymers except for the MMA‐pCS copolymers with low MMA contents. The relaxation time for pure poly(methyl methacrylate) could be interpreted by the Kramers theory at the high‐friction limit.