Model Filled Polymer 7: Flow behavior of Polymers Containing Monodisperse Crosslinked Polymeric Beads.

摘要

Steady shear viscosities and dynamic moduli of polymer composites, consisting of combinations of crosslinked beads and matrices of polystyrene (PS) and polymethacrylates (PMA), are measured in a cone and plate rheometer. Viscosities and moduli were very sensitive to chemical composition. Crosslinked beads of identical composition to the matrix exhibited the lowest viscosity enhancements at low shear rates and the lowest moduli in dynamic mechanical properties analysis. The effects of bead concentration on rheological behavior were compared for PS and PMMA beads in a PMMA matrix. PMMA beads produce small effects, whereas, PS beads yielded highly non-Newtonian systems in PMMA, showing a yield stress of 1100 Pa at 30 wt% filler loading, and dynamic moduli independent of frequency. We suggest that rheological behavior reflects the state of dispersion of beads in the matrix. Beads identical in composition to the matrix yield uniform dispersions. We propose that uniform and stable bead dispersions exhibit the lowest viscosity and moduli.