Haze and extinction for a composite medium with quasitransparent optically stratified particles

Abstract

AbstractHaze and extinction are studied for coreshell particles in a matrix near transparency. It is shown that, close to transparency, a core‐shell particle behaves optically differently from a nonstructured particle due to the presence of a minimum in the scattering pattern for any particle size. For small particles or domains (<λ/2), this difference is more pronounced. In particular, compositional effects on haze and extinction are studied. It is found that under certain conditions, for the same global composition, strongly optically stratified par‐ticles give lower haze than the homogeneously distributed one by one to two orders of magnitude. The same occurs with the extinction coefficient, however the global composition at which this becomes important differs from that corresponding to a minimum haze. The origin of this difference is discussed in the light of the structure of the scattering pattern in each case. This implies that, for a transparent polymer blend with stratified domains, the minimum haze, maximum transmission and the theoretically perfect matching com‐positions, are all different. Finally, it is shown that, for small highly optically inhomogeneous core‐shell particles, haze goes through an inflection point with increasing particle size, in contrast with the usual monotonically increasing, singly concave, behavior. © 1993 John Wiley & Sons, Inc.