INTERFACIAL BONDING AND OPTICAL-TRANSMISSION FOR TRANSPARENT FIBERGLASS POLY(METHYL METHACRYLATE) COMPOSITES/

Evidence is presented relating the interfacial bonding strength and th e optical transmission of transparent glass fiber reinforced PMMA comp osites. The temperature dependent (20 degrees to 50 degrees C) optical transmission of composites that contained uncoated 13 mu m glass fibe rs and 13 mu m glass fibers coated with divinyltetramethyl disilazane or 3-(trimethoxysilyl)propyl methacrylate was found to decrease in the same order as the bond strength of the PMMA/glass fiber interface, na mely, trimethoxy silane coated fiber, disilazane coated fiber, and unc oated fiber. SEM photographs showed similar fracture surfaces, clean f iber pull-out, and no apparent bonding of the glass fiber to the PMMA for the composites containing uncoated and disilazane coated fiber, wh ereas, the composite containing trimethoxy silane coated fiber showed virtually no clean fiber pullout. Additional evidence for differences in the bonding strength is seen in the degradation (penetration of wat er and fiber whitening) on aging at 23 degrees C in air or water for c omposites containing uncoated fiber (most degradation), disilazane coa ted fiber (slight degradation), and trimethoxy silane coated fiber (no degradation). The optical transmission between 20 degrees and 30 degr ees C at 600 to 800 nm for the composite containing trimethoxy silane coated fiber decreased the least with increasing temperature (from sim ilar to 85% to 70%) while the composite containing uncoated fiber decr eased the most(from similar to 85% to 32%).