We report a study of the local dynamics in polyisobutylene (PIB) melts using quasi-elastic neutron scattering (QENS). QENS measurements were carried out on the high resolution back-scattering spectrometer IRIS (ISIS) in the temperature range 300-460 K. The QENS data were analysed in the time domain, in order to extract information on the alpha-process in PIB. We show that time-temperature superposition is obeyed. The temperature dependence of the shift factors derived by QENS is in good agreement with C-13 NMR and ESR literature data. However, the temperature dependence of the molecular motion observed by QENS differs considerably from the one determined from viscosity and neutron spin echo measurements. (C) 2002 Published by Elsevier Science B.V.
Temperature dependence of the segmental dynamics
2002
Abstract
We report a study of the local dynamics in polyisobutylene (PIB) melts using quasi-elastic neutron scattering (QENS). QENS measurements were carried out on the high resolution back-scattering spectrometer IRIS (ISIS) in the temperature range 300-460 K. The QENS data were analysed in the time domain, in order to extract information on the alpha-process in PIB. We show that time-temperature superposition is obeyed. The temperature dependence of the shift factors derived by QENS is in good agreement with C-13 NMR and ESR literature data. However, the temperature dependence of the molecular motion observed by QENS differs considerably from the one determined from viscosity and neutron spin echo measurements. (C) 2002 Published by Elsevier Science B.V.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
