Model for the temperature dependent transmission of optically transparent poly(methyl methacrylate) composites

Abstract

An infinite cylinder model was used to predict the optical transmission of transparent composites containing unidirectionally aligned glass fibers. The parameters used in the model are the volume content and diameter of the glass fibers, the refractive index of the fiber and matrix, the nonwet fiber content, the thickness of the composite, and the temperature coefficient of the refractive index of the matrix. The transmission calculated from the model agreed well with the measured temperature-dependent transmission of a composite from 20 to 70 °C for thin specimen (<1.0 mm) containing fiber less than 10 vol. %. The model showed that a small amount of nonwet fiber (0.7% of fiber content) could cause a substantial reduction in the maximum transmission. The content of nonwet fibers should be as small as possible for making a highly transparent composite.