6533b855fe1ef96bd12b1b29

RESEARCH PRODUCT

On the Role of Drop Break Up for Coalescence Processes and Morphology Development in Polymer Blends under Shear

subject

description

Drop sizes and drop-size distributions were determined as a function of time at constant shear rates, γ, by means of an optical shear cell in combination with an optical light microscope after preshearing the samples at high γ. The systems under investigation were PIB 3/PDMS 152 (PIB:  polyisobutylene, PDMS:  poly(dimethylsiloxane), numbers:  average molar masses in kg/mol) and COP 26*/PDMS 48 (COP:  poly(dimethyl-co-methylphenylsiloxane), asterisk:  apparent molar mass); all measurements refer to 25 °C. Systems and conditions were chosen such that shear rates in the vicinity of the intersection of the coalescence and the break up curves become experimentally accessible. Under these conditions, it is important to evaluate the different processes not only in terms of average drop radii but also in terms of their distribution. Such an analysis demonstrates that there exists a kind of transition from the typical behavior at low shear rates (far below the intersection, only coalescence, approach of dead-end...