Phase Separation Dynamics of a Poly(Vinyl Methyl Ether)/Polystyrene (PVME/PS) Blend Studied by Ultrafast Differential Scanning Calorimetry

摘要

In this work, ultrafast differential scanning calorimetry (UFDSC) is used to study the dynamics of phase separation. Taking poly(vinyl methyl ether)/polystyrene (PVME/PS) blend as the example, we firstly obtained the phase diagram that has lower critical solution temperature (LCST), together with the glass transition temperature (T-g) of the homogeneous blend with different composition. Then, the dynamics of the phase separation of the PVME/PS blend with a mass ratio of 7: 3 was studied in the time range from milliseconds to hours, by the virtue of small time and spatial resolution that UFDSC offers. The time dependence of the glass transition temperature (T-g) of PVME-rich phase, shows a distinct change when the annealing temperature (T-a) changes from below to above 385 K. This corresponds to the transition from the nucleation and growth (NG) mechanism to the spinodal decomposition (SD) mechanism, as was verified by morphological and rheometric investigations. For the SD mechanism, the temperaturedependent composition evolution in PVME-rich domain was found to follow the Williams-Landel-Ferry (WLF) laws. (C) 2017 Wiley Periodicals, Inc.