Temperature dependence of the segmental dynamics in polyisobutylene melts

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 α-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 13 C 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.