Determination of Shape of Kaolin Pigment Particles

Abstract

Characterization of platiness of kaolin pigments was derived from the divergence of measurements of their particle size distribution by two different techniques: sedimentation and light scattering. A numerical shape factor, which is related to the ratio of kaolin particle face diameter to its thickness, can be calculated to provide a quantitative measure of such platiness. Two sets of kaolin pigments were prepared from a Middle Georgia kaolin: delaminated and non-delaminated. Shape factors of delaminated samples were higher than those of non-delaminated ones. Maximum platiness was found between equivalent volume diameters of 1·0 and 2·0 μm. Examples are presented where properties of coated paper are correlated with the size and shape of kaolin pigments.

Polyvinylpyrrolidone Adsorption and Structural Studies on Homoionic Li-, Na-, K-, and Cs-Montmorillonite Colloidal Suspensions

“…In the case of M-montmorillonite particles, the observed discrepancy in d n and d τ values between the two turbidimetric methods must thus be related to the the peculiar scattering efficiency rules for asymetric particles not treated in the classical Mie scattering theory for spherical particles. Indeed, in the case of plate-like particles with a typical axial ratio >200, the absolute scattering efficiency depends on the particle axis as predicted for the light scattering of ellipsoids (19,20). However, similar size ranges obtained by PCS (d z ) and turbidimetry (wavelength exponent method, d n ) confirm that the particle average major dimension (a, b axes) is the determining physical parameter in these two independent sizing methods.…”

Determination of clay mineral aspect ratios from conductometric titrations

“…Furthermore, the agreement between particle size distributions may be influenced by the fact that only average values of the aspect ratio are obtained by conductometric titrations. The aspect ratio can be substantially different in different size fractions of a sample (Slepetys & Cleland, 1993).…”

Engineering minerals for performance applications: an industrial perspective

“…It is important to note that a particle which reports at a given esd by sedimentation would not necessarily report at the same esd by light scattering, because the two techniques measure different properties of the particles which are each dependent upon the particle shape in different ways. Indeed, the differences between the results of the different measurements can be used to extract information on particle morphology (Slepetys & Cleland, 1993). For particles greater than a few microns in size, it is becoming common to use microscopy in combination with high speed image analysis to measure size distributions.…”