Fabrication and optical/thermal properties of glass particle-epoxy optically transparent composites

The possibility of fabricating a new type of optically transparent glass particle dispersed epoxy matrix composite by tailoring the refractive index of the particle and matrix was studied. Glass particles with an average diameter of approximate to 8 mu m were incorporated into a clear epoxy matrix and the particle volume fraction ranged from 0.01 to 0.17. The refractive index difference after fabrication was less than 10(-3). The light transmittance of the composite in the UV-visible region and the coefficient of thermal expansion (CTE) of the composite were measured. The results demonstrated that the optically transparent composite was obtained with a lower CTE than the pure epoxy matrix. The light transmittance of the composite decreased with increase in particle volume fraction, while the CTE of the composite showed an opposite tendency. The light transmittance of the composite was explained theoretically by a refractive index matching in the composite, which was different from that of the raw materials owing to thermal stress. (C) 1997 Acta Metallurgica Inc.