Rheological behavior of concentrated suspensions as affected by the dynamics of the mixing process

The rheological characterizations of concentrated suspensions are generally carried out assuming “well-mixed” suspensions. However, the variation of the concentration distributions of the ingredients of the formulation, i.e., the “goodness of mixing”, the size and shape distributions of the particle...

Full description

Saved in:

Bibliographic Details
Published in:	Rheologica acta Vol. 45; no. 5; pp. 641 - 658
Main Authors:	KALYON, Dilhan M, DALWADI, Dharmesh, EROL, Melek, BIRINCI, Elvan, TSENOGLU, Christos
Format:	Journal Article
Language:	English
Published:	Berlin Springer 01-06-2006 Springer Nature B.V
Subjects:	Applied sciences Binding energy Clusters Composites Elasticity Elastomers Electrical measurement Electrical properties Exact sciences and technology Forms of application and semi-finished materials Graphite Gravimetric analysis Ingredients Light diffraction Polymer industry, paints, wood Rheological properties Rheology Rheometry Shear viscosity Slip velocity Storage modulus Technology of polymers Viscosity Wall slip Mixing Electrical properties Suspension rheology SEBS Rheology Thermoplastic rubber Suspension Experimental study Property processing relationship Processing equipment Composite material Concentrated suspension Shear viscosity Triblock copolymer Particle size distribution Graphite Mixedness Concentration distribution Rheological properties
Online Access:	Get full text
Tags:	Add Tag No Tags, Be the first to tag this record!

Description
Summary:	The rheological characterizations of concentrated suspensions are generally carried out assuming “well-mixed” suspensions. However, the variation of the concentration distributions of the ingredients of the formulation, i.e., the “goodness of mixing”, the size and shape distributions of the particle clusters and the rheological behavior of the suspension all depend on the thermo-mechanical history that the suspension is exposed to during the mixing process. Here, various experimental tools are used for the characterization of the degree of mixedness (concentration distributions) of various ingredients along with the characterization of rheological material functions, wall slip behavior and the maximum packing fraction of a graphite/elastomer suspension. The degree of mixedness values of the ingredients of the suspensions processed using batch and continuous processes and under differing operating conditions were characterized quantitatively using wide-angle X-ray diffraction and thermo gravimetric analysis and were elucidated under the light of the electrical properties of the suspension as affected by the mixing process. Upon achieving better homogeneity of the graphite particles and the binder and decreases in the size and breadth of the size distributions of particle clusters (as inferred from electrical measurements and maximum packing fraction values), the elasticity (storage modulus) and the shear viscosity (magnitude of the complex viscosity from small-amplitude oscillatory shear and shear viscosity from steady torsional and capillary rheometry) of the suspension decreased significantly and the wall slip velocity values increased. These findings demonstrate the intimate relationships that exist between the rheological behavior of concentrated suspensions and the thermo-mechanical history that they are exposed to during the processing stage and suggest that the preparation conditions for suspensions should be carefully selected and well documented to achieve reproducible characterization of rheological material functions.
ISSN:	0035-4511 1435-1528
DOI:	10.1007/s00397-005-0022-x