Correlation with light scattering data

In many industries, particle size measurements have been carried out historically by sieve analysis and light scattering instruments are increasingly replacing this. In order to correlate with historic data banks some manufacturers have software to manipulate the data so as to present the size distribution in terms of sieve diameter. 

Equivalent volume diameter (pm) Mass percentage undersize  

Tests carried out on pneumatically conveyed salt particles showed that Insitec data gave size distributions that were over 30% coarser than sieve data, the difference being attributable to particle shape effects. The results for both instruments showed that the particles attrited with number of passes through the system, with the Insitec being more sensitive than sieving [118]. 

According to Heywood [1] sieving is the Cinderella of particle size analysis methods it does most of the hard work and gets little consideration. This was reiterated by Leschonski [119] who also quotes the chairman of the Institution of Mining and Metallurgy as stating, in 1903, that screening is not a scientific means of measurement. 

For accuracy, it is necessary that the sieves be calibrated and, if the sieves are dedicated to a single powder, the calibration should be carried out with the powder under test. It is also necessary that the sieves be checked, on a regular basis using a calibration powder, so that worn sieves can be rejected. Normally, if a sieve analysis is plotted on log-probability paper, a smooth curve results any points lying off the curve should be viewed with suspicion. 

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Figure 5B. Correlation of right-angle light scatter measured by fluorometry and flow cytometry. The top panel shows flow-cytometric data of side scatter of fixed, stained cells during the time course of stimulation by 1-nM (solid line, solid circles) or 0.01-nH (dashed line, open circle) FLPEP. The bottom panel shows the corresponding right-angle light-scatter data acquired pseudo-simultaneously on live cells in the fluorometer. The flow-cytometric data have been averaged, but the fluorometry data are plotted for both duplicates from one donor. Reproduced with permission from Ref. 27. Copyright 1985 Rockefeller University Press.

Figure 31 Concentration dependence of the correlation length (in salt-free polyelectrolyte solutions. Filled symbols corresponds to the small-angle neutron scattering (SANS) data (circles) (Nierlich, M. etal. J. Phys. (Paris) 1979, 40, 701 ) and light scattering data (squares) (Drifford, M. Dalbiez, J. P. J. Phys. Chem. 1984, 88,5368 ) in solutions of NaPSS. Open symbols represent results of the molecular dynamics simulations. The lines with slope -1/2 are shown to guide the eye. Reproduced with permission from Dobrynin, A. V. Rubinstein, M. Prog. Polym. Sci. 2005, 30,1049-1118. Copyright 2005, Elsevier.

Also, a good correlation between Mw (light scattering) and intrinsic viscosity is observed for [Ph(Me)PN]n over the molecular weight range of the samples studied. Thus, the Mark-Houwink relationship, [rj] = K(AOa, yields values of K = 1.44x1 o 4 (with [rj] in dL/g) and a = 0.66. These data again indicate a well solvated, extended-chain structure of the polymer in THF. 

Photon correlation light scattering was carried out by methods described elsewhere (6) to give the (unnormalized) correlation function G( )(q,T). Data were obtained with vertically polarized incident light for G 5)(q,T) and Gjj5)(q,T) obtained, respectively, with the vertical and horizontal components of the scattered light. 

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