On the molecular microstructure dependence of space charge trapping in polymers

The space charges trapped after applying a strong electrical field have been measured using the thermal step (TS) method for a series of poly(vinylchloride) (PVC) samples differing in their tacticity-induced molecular microstructure. This has been controlled chemically (stereospecific substitution reactions) or physically (stretching of films at temperatures near T-g). From some of the results obtained, most of which are still to be published, the space charge quantity and distribution are inferred to depend strongly on the content of the isotactic tetrad mmr and on the two conformations, whether GTTG(-)TT or GTGTTT, which are probably in it. (C) 1998 SCI.