title: The segmental and chain relaxation modes in high-cis-polyisoprene as studied by thermally stimulated currents.
abstract: The technique of Thermally Stimulated Currents is used to study the slow molecular mobility in a series of poly (1,4-cis-isoprene) samples with different molecular weights, Mw, and low polydispersity. The technique revealed a high resolution power, particularly useful in the study of the lower molecular weight samples where the chain and the segmental relaxations strongly overlap. The dynamic crossover that is reported for the normal mode by varying the molecular weight is clearly revealed by the thermally stimulated depolarization currents results through the temperature location, TMn, of the normal mode peak, the values of the relaxation time at TMn, τ(TMn), and the value of the fragility index of the normal mode, mn. The kinetic features of the glass transition relaxation of polyisoprene have also been determined.
authors: CQE-Centro de Química Estrutural, Universidade de Lisboa, Complexo I, IST, 1049-001 Lisboa, Portugal.
authors: Elsa
authors: E
authors: Mora
authors: Jülich Centre for Neutron Science and Institute for Complex Systems, Forschungszentrum Jülich, 52425 Jülich, Germany.
authors: Ana R
authors: AR
authors: Brás
authors: Jülich Centre for Neutron Science and Institute for Complex Systems, Forschungszentrum Jülich, 52425 Jülich, Germany.
authors: Wim
authors: W
authors: Pyckhout-Hintzen
authors: CQE-Centro de Química Estrutural, Universidade de Lisboa, Complexo I, IST, 1049-001 Lisboa, Portugal.
authors: Hermínio P
authors: HP
authors: Diogo
authors: CQFM-Centro de Química-Física Molecular and IN-Institute of Nanoscience and Nanotechnology, Instituto Superior Técnico, Universidade de Lisboa, 1049-001 Lisboa, Portugal.
authors: Joaquim J
authors: JJ
authors: Moura Ramos