The Mechanical and Optical Properties of Injection-moulded PMMA, Filled with Glass Particles of a Matching Refractive Index

Refraction of light at the interface of two materials occurs if they have different refractive indices (RI). Therefore, it is theoretically possible to produce bright, transparent, glassreinforced polymers by matching the materials’ RI. This largely depends, among other factors, on the wavelength of the incident light (dispersion) and on the temperature of the material (thermo-optic coefficient), whereby the RI of polymers in the visual range increases with decreasing wavelength and temperature1,2 and the refractive index of glass also decreases with the wavelength but usually increases with increasing temperatures3. Whereas the dispersion of transparent polymers and optical glass may be identical, the thermooptic coefficient ∆nrel/∆T of glass has a value between -5.4 and 32.2x 10-6/K 4. Polymers have a negative thermo-optic coefficient, which is nearly two orders of magnitude higher5. These facts lead to a wavelength-dependent and at least temperature-dependent transmission of the aforementioned composites6.