Shining a Light on Carbon-Reinforced Polymers: Mg/MgO and TiO2 Nanomodifications for Enhanced Optical Performance

This study examines the intrinsic optical enhancements of carbon fiber-reinforced polymers (CFRPs) achieved through the integration of magnesium oxide (MgO) nanoparticles, as well as Mg/MgO and titanium dioxide (TiO2) thin films onto carbon fibers. Integration was performed by quasi-continuous electrophoretic deposition (EPD) and physical vapor deposition (PVD), respectively. Employing a customized electrophoretic cell, EPD facilitated uniform MgO nanoparticle deposition onto unsized carbon fibers, ensuring stable nanoparticle dispersion and precise fiber coating. As a result, the fibers exhibited increased ultraviolet (UV) reflectance, largely attributed to the optical properties of the protective MgO layer. In parallel, PVD enabled the deposition of Mg/MgO and TiO2 thin films with tailored thicknesses, providing precise control over key optical parameters such as reflectivity and interference effects. Mg/MgO coatings demonstrated high UV reflectivity, while TiO2 layers, with their varying refractive indices, generated vibrant colors in the visible (Vis) range through thickness-dependent light interference. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) assessed the quality, thickness, and uniformity of these thin films, and UV/Vis spectroscopy confirmed the influence of deposition parameters on the resulting optical performance. Post-lamination analyses revealed that both EPD and PVD modifications significantly enhanced UV reflectivity and allowed for customizable color effects. This dual strategy underscores the potential of combining EPD and PVD to develop advanced CFRPs with superior UV resistance, decorative optical features, and improved environmental stability.