proceedings article

Abstract

The evolution of the morphology of polymer blends compounded in single screw extrusion followed in line by a static mixer proceeds through the formation of sheets. These sheets subsequently break-up into threads or droplets or form co-continuous morphologies. The decrease of phase dimensions during blending can be quantitatively described by the shear deformation of these sheets. The final phase dimensions are determined by the thickness of the sheet at the onset of break-up. The type of morphology changes during further processing but the phase dimensions do not change significantly any more. The relevant Capillary number is based on the phase sizes at sheet break-up. At high values of this number the liquid threads remain relatively stable and fibre/matrix or co-continuous morphology is formed. At lower values the threads break and droplet/matrix morphology is formed. The final phase sizes are almost independent of the Capillary number. The sheets are shown to be the precursors of the co-continuous morphology. Depending on the stability of the network of ligaments in the mixer after sheet break-up the co-continuous morphology is either an intermediate type of morphology or a final (stable) morphology.

proc. 15th pps conference, 249:1-10, 1999

Morphology development in immiscible polymer blends: initial blend morphology and phase dimensions