Particle size distribution by turbidimetry

Abstract

Abstract A turbidimetric method for rapidly estimating particle size distribution parameters for latex systems has received intensive evaluation. This method originally proposed by W. Heller and co‐workers [J. Chem. Phys. 34, 1796 (1961)], and based on Mie theory, involves the generation of theoretical turbidity functions versus wavelength and the comparison of these theoretical curves with ones determined experimentally. A digital computer program involving the use of a lattice search technique by minimization of residual sums of squares over a response surface was developed and used for comparing these curves. It has been found that this curve matching leads to multivalued solutions and, unless prior estimates of the answer from some other technique are available, there are no criteria for choosing between alternative solutions. The response surface is in the form of a “trench” rather than a unimodel “depression.” Consideration of typical experimental errors for this technique yields quite large areas of uncertainty in the final answers further complicating the analysis of results. These findings indicate that this method, though very attractive because of the simplicity of the experimental technique, should not be used alone for particle size analysis and hence cannot be considered a routine or simple procedure.