Lambla Award - Morphology Generation in Polymer Blends
Uttandaraman Sundararaj
University of Alberta, Department of Chemical and Materials Engineering, University of Alberta, Edmonton, Alberta
Canada

Keywords: polymer blends, drop breakup, coalescence

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Polymer blending has become the preferred method to create new polymer materials with improved performance and enhanced properties. It has been discovered that there is an initial rapid decrease in particle size during melting or softening, and that after that, there is a steady state particle size due to the competing forces of drop breakup and coalescence. In this talk, the previous work on morphology generation in blends will be summarized and recent work on visualization and numerical modeling of drop breakup will be presented. It is difficult to visualize the real polymer blending process because of high processing temperatures and sub-millimeter size drops, but visualization can be performed using specially designed apparatuses. In this work, we investigated drop breakup after melting using visualization and numerical modeling incorporating heat transfer in the melt and the drop. The deformation of millimeter size pellets into micron size particles occurs partly due to the melting that occurs during polymer blending. The polymer breakup phenomena visualized are very different from that seen in Newtonian fluids and model elastic fluids. The numerical model includes viscous dissipation and non-Newtonian rheology to simulate the heat transfer, melting and breakup of a polymer drop inside another polymer melt. The numerical model gives us insight into the reasons for the visualized drop breakup.