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The optical properties of two‐phase polymer systems: Single scattering in monodisperse, non‐absorbing systems
Author(s) -
Conaghan B. F.,
Rosen S. L.
Publication year - 1972
Publication title -
polymer engineering and science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.503
H-Index - 111
eISSN - 1548-2634
pISSN - 0032-3888
DOI - 10.1002/pen.760120210
Subject(s) - materials science , dispersity , polymer , scattering , phase (matter) , light scattering , optics , polymer chemistry , composite material , organic chemistry , physics , chemistry
Two‐phase polymer systems have achieved commercial importance due mainly to the improvement in impact strength brought about by the addition of dispersed rubber particles to a normally brittle glassy polymer. Rubber‐reinforced polystyrene and ABS plastics are two familiar examples. An important drawback of this class of materials is their lack of transparency, caused by the scattering of light at the interface between the phases. The theory of light scattering by spherical particles indicates that the degree of scattering (turbidity) is a function of the amount of dispersed phase present, its particle size, the ratio of refractive indices of the phases, and the wavelength of light. Quantitative predictions of the effects of the above parameters on the transparency of two‐phase systems can be made, providing answers to the questions “How close must the refractive indices be?” and “What size must the dispersed‐phase particles be?” for a given level of transparency. Calculations for typical polymer pairs reveal that at a given dispersed‐phase level, a maximum in turbidity is obtained roughly in the range of particle sizes thought to be necessary for good impact strength. Also, if the refractive indices are matched at a particular temperature, small particle sizes greatly increase the temperature range over which scattering is minimized.