Tacticity and dielectric relaxation around the glass transition of poly(vinyl chloride). A thermally stimulated depolarization currents (TSDC) study

Abstract

AbstractThe thermally stimulated depolarization currents (TSDC) technique has been used to study molecular motions around the glass transition in three different samples of poly(vinyl chloride) (PVC) varying in the contents of isotactic triads. The α‐relaxation mode associated with cooperative molecular motions taking part in glass transition appears to be strongly dependent on tacticity. A secondary relaxation mode α′, different from the β‐relaxation, has been detected just below the α‐relaxation and at temperatures depending on the content of isotactic triads. Above the glass transition temperature the TSDC curves show a ρ‐peak corresponding to the motion of free charges in the material. This process does not seem to be affected by tacticity. The results suggest that specific conformations of isotactic triads play an important role in the motion of chain segments in the polymer.