Simultaneous Estimation of the PSD and the Particle Refractive Index of a Latex of Unknown Composition from Combined Optical Measurements

VEGA, J.R.; GONZALEZ, V.D.; FRONTINI, G.L.; ELICABE, G.E.; GUGLIOTTA, L.M.

Graz (Austria)

Congreso; 8th Int. Congress on Optical Particle Characterization (OPC 2007); 2007

OPC 2007

Independent measurements of Elastic Light Scattering (ELS), I(q) at several angles q, and Turbidity (T), t(l) at several wavelength l, are combined to simultaneously estimate the particle size distribution (PSD), f(D), and the particle refractive index (PRI), np(l), corresponding to a dilute polymer colloid of unknown composition. The problem is solved in 3 sequential steps: (i) an initial PSD estimate f0(D) is obtained from I(q), on the basis of an “a priori” guess (or measurement) of the PRI at the ELS wavelength l0, np(l0); (ii) np(l) is estimated from t(l) and f0(D); and (iii) an improved PSD is estimated by combining I(q), t(l), and np(l), in a single inverse problem. The proposed method was validated through numerical and experimental examples. For the experimental validation, an industrial latex used for formulating a pressure-sensitive adhesive was measured.