Poly(ether-block-sulfonated ester) copolymers. II. Mechanical and dielectric relaxation

This work reports mechanical and dielectric relaxation studies of multibloc k copolymers based on flexible segments of poly(1,4-oxytetramethylene) (PTM O) and rigid crystalline segments of poly(butylene terephthalate) (PBT) mod ified by ionic units [poly(ether-block-sulfonated ester), PESE]. The dynami c mechanical thermal analysis (DMTA) results indicate that PESE should beha ve as unvulcanized rubbers at ambient temperature. The changes in the inten sities of dielectric relaxation peaks for the beta- and gamma -processes wi th respect to concentration of rigid segments and ionic unit content in the se segments were found to be associated with corresponding changes in cryst alline structure and morphology of the PESE. The mechanical and dielectric results show that the degree of crystallinity decreased with increasing con tent of ionic groups in the polyester rigid segments. At higher concentrati ons of rigid segments modified by ionic units, the presence of a relaxation that can be due to the ionic aggregation was observed in the DMTA and diel ectric spectra.