ARTICLE NO. CS975029 NOTE Estimation of Gelatin Layer Thickness on Polystyrene Particles by a Viscometric Study tion (9), and viscometric techniques. Ellipsometry (8) has been used to determine the thickness of the adsorbed layer of simple homopolymers but A viscometric method has been used to determine the layer
has not yet been successfully applied to heterogeneous polymer system thickness of gelatin adsorbed on polystyrene (PS) particles. The (although ellipsometry may be extended to cover heterogeneous systems, layer thickness was found to be 28 nm regardless of the diameter of it does not seem feasible to apply it to small particles in suspensions).
PS particles. The value of Einstein's coefficient, a 0 for the relative
Sedimentation ( 9) rate has been used to compute layer thickness of moleviscosity-volume fraction relation was estimated to be 2.63. Since cules adsorbed on particulate suspensions. In this method, however, we the PS latex particles were spherical, the value of a 0 indicates that must assume that the particle size distribution is narrow and that the particles even at high shear rates, some aggregation still occurred in the are spherical. Viscometry is another method which is widely used to mea- dispersion.