title: Effect of volume changes on segmental relaxation in siloxane polymers.
abstract: From dielectric relaxation and equation-of-state measurements on polymethylphenylsiloxane and polymethyltolylsiloxane, the relative contributions of volume and thermal energy to the temperature dependence of the segmental relaxation times are quantified. In both polymers, volume exerts a substantial effect, being almost as significant as thermal energy. A possible consequence of this prominent role of volume in governing the segmental dynamics is the finding that the relaxation times, measured for a series of temperature at various (fixed) pressures, can be expressed as a single function of the volume normalized by the volume at the glass transition temperature. A similar result is found for the (isothermal) relaxation times measured at various pressures.
authors.affiliation: Institute of Physics, Silesian University, Uniwersytecka 4, 40-007 Katowice, Poland.
authors.forename: M
authors.initials: M
authors.lastname: Paluch
authors.forename: R
authors.initials: R
authors.lastname: Casalini
authors.forename: A
authors.initials: A
authors.lastname: Patkowski
authors.forename: T
authors.initials: T
authors.lastname: Pakula
authors.forename: C M
authors.initials: CM
authors.lastname: Roland