The Role of Particle Forces in Determining the Rheological Properties of Concentrated Dispersions. An Experimental Study
The forces of interaction between two mica surfaces bearing an adsorbed layer of a poly-2—vinyl—pyridine/polytert—butylstyrene (P2VP/PtBS) AB block copolymer of molecular weight 21 400 has been measured. The forces commence at a surface separation of some 50 nm and increase approximately exponentially with decreasing surface separation. An increase of three orders of magnitude in the force is measured. Subsequently polyacrylonitrile (PAN) particles, stabilised by the same P2VP/PtBS AB block copolymer, have been prepared and the rheological properties of these dispersions determined up to high volume fraction ø <0.6. Particular emphasis has been put on the storage modulus of these dispersions, which increases exponentially with increasing ø also by three orders of magnitude. The storage modulus should be proportional to the differential of the particle force—distance profile. Using a cellular model the two sets of experimental data may be related and correspondence between the data achieved.
KeywordsBlock Copolymer Storage Modulus Adsorbed Polymer Mica Surface Force Profile
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