Polymer dynamics in a crosslinked poly(ethylene oxide-propylene oxide) random copolymer, both neat and doped with an inorganic salt, is investigated by means of quasi elastic neutron scattering (QENS) as a function of temperature and momentum transfer. Data from two backscattering instruments with complementary resolution and setup are reported. We present an original approach to the analysis of inelastic fixed energy scans. The findings from this approach lead to a detailed description of the polymer dynamics across the glass transition, which is confirmed by a more conventional analysis carried out on Fourier transformed QENS data in the temporal domain. The neat polymer dynamics is modelled in terms of two relaxation processes: below the glass transition, the methyl side group hopping relaxation has been characterised and compared with the similar process occurring in pure polypropylene-oxide. Above the glass transition, a non Debye, non Arrhenius relaxation occurs, corresponding to the polymer segmental dynamics. In the case of the salt doped rubber, the segmental dynamics is found to be more complex: while the methyl group dynamics is not affected by the salt addition, the present data set supports the view of a bimodal segmental dynamics as a consequence of salt addition.
Quasi elastic neutron scattering investigation of dynamics in polymer electrolytes
A Triolo;
2004
Abstract
Polymer dynamics in a crosslinked poly(ethylene oxide-propylene oxide) random copolymer, both neat and doped with an inorganic salt, is investigated by means of quasi elastic neutron scattering (QENS) as a function of temperature and momentum transfer. Data from two backscattering instruments with complementary resolution and setup are reported. We present an original approach to the analysis of inelastic fixed energy scans. The findings from this approach lead to a detailed description of the polymer dynamics across the glass transition, which is confirmed by a more conventional analysis carried out on Fourier transformed QENS data in the temporal domain. The neat polymer dynamics is modelled in terms of two relaxation processes: below the glass transition, the methyl side group hopping relaxation has been characterised and compared with the similar process occurring in pure polypropylene-oxide. Above the glass transition, a non Debye, non Arrhenius relaxation occurs, corresponding to the polymer segmental dynamics. In the case of the salt doped rubber, the segmental dynamics is found to be more complex: while the methyl group dynamics is not affected by the salt addition, the present data set supports the view of a bimodal segmental dynamics as a consequence of salt addition.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
