Light scattering and reflectance of optically heterogeneous oriented polymers

Abstract

A simple approach is used to measure the reduced scattering coefficient μ′s of a thick turbid medium having a small absorption coefficient μ′a << μ′s. Based on the light reflectance measurement of semi-infinite media with a CCD camera, the shift between the centre of the incident laser beam and the centre of the diffuse background. Δx, is determined which is inversely proportional to μ′s. The experimental values of μ′s determined for (i) EPDM particles in a polypropylene matrix and (ii) the specific case of oriented PMMA domains in a polycarbonate matrix are compared with model calculations using the Lorenz-Mie theory and a simple approximation of light scattering theory by spheroidal particles. A comparison of theoretical data with parameters from image analysis of SEM pictures gives a good accord. The dependence of light scattering patterns on mutual orientation of incident light beam and of spheroidal particles is discussed.