PREPARATION AND PROPERTIES OF OPTICALLY TRANSPARENT, PRESSURE-CURED POLY(METHYL METHACRYLATE) COMPOSITES

The objective of this work was to develop optically transparent glass fiber reinforced poly(methyl methacrylate) (PMMA) composites by matchi ng the refractive index of the glass fiber reinforcement to that of th e PMMA matrix, thereby minimizing the quantity of light which is norma lly scattered and reflected at the interface of dissimilar materials. A pressure curing process is described for preparing composites 10 by 15 by 0.6 cm thick and containing up to approximately 35 vol% glass fi ber. By curing at 65-degrees-C under 6.9 MPa N2 for 18 h, composites h ave been produced with optical quality surfaces and flexural strengths more than seven times that of commercial PMMA of the same thickness. A transparent composite containing 10.4 vol% of 13 mum diameter fiber had an 84% optical transmission (92% maximum for PMMA) at 600 nm and 2 5-degrees-C.