Assessing the Phase Structure of Molten Polymer Blends using a Generalized Gramespacher-Meissner Model

Description

Oscillatory shear rheometry is a convenient method to detect phase separation in polymer melts, as the deformation of enclosed particles will cause additonal long-time relaxation processes which add to the dynamic moduli at low frequencies. When using rheometry to investigate the phase structure of a molten polymer blend, it makes sense to avoid crystallization during sample preparation, as it induces phase separation and might therefore affect the measurement. Thus we use an experimental set-up where the compounded molten blend is transferred directly into the measuring cell of a rheometer. If phase separation in the melt occurs, the relaxation time spectrum obtained from the measured dynamic moduli will differ significantly from the combined spectra of the pure components. By using the model of Gramespacher and Meissner [1], one can gather information about the phase structure from this discrepancy. However, the original G/M model is only valid for (near) uniform particle sizes. We therefore attempt to generalize it in order to make it applicable to broader particle size distributions. We use this model to predict the dynamic mechanical behaviour of blends with known morphologies, and, conversely, to assess the morphology from measured dynamic moduli. Reference: [1] H. Gramespacher and J. Meissner (1992): J. Rheol. 36(6), 1127-1141

Period	11 Apr 2014
Event title	9th Annual European Rheology Conference (AERC2014)
Event type	Conference
Location	GermanyShow on map