Investigating the Effects of Particle Size using Photoluminenscence Piezospectroscopy

Nanoparticle-reinforced composites are greatly known in the aerospace community for their improved tailorable quasi-isotropic properties, such as its strength-to-weight to weight ratio and fracture toughness. The particle dispersion of these nanocomposites can be tailored by manipulating multiple factors, such as volume fraction, particle size, and shape. Agglomerations and insufficient particle dispersion have a detrimental effect on the particle/matrix bonding strength and load transfer. Photoluminescence (PL) spectroscopy is a non-destructive technique that offers high spatial resolution measurements that can assess the dispersion of alpha−alumina nanoparticles in an epoxy matrix. PL has been used to establish the effects of particle size on the nanocomposite’s dispersion with 100 nm, 150 nm, and 350 nm Cr3+ doped alpha-alumina nanoparticles in an EPON 826 matrix. It has been found that the R-lines increasingly scale as the particle size increases. Intensity contour maps demonstrate the 350 nm particle size offers the best particle dispersion followed by the 150 and 100 nm with increasing agglomerations. Normalized particle distribution curves have been quantified using a full-width half-max (FWHM) approach demonstrating that the 150 nm has superior dispersion to the 100 nm. The 350 nm has shown, due to its intense range of emissions, it is difficult to be directly compared to the 100 and 150 nm. While the effects of particle size are observed in the contour plots, more specimens of the same particle sizes will need to be assessed to define this relationship. These findings will be used to optimize the dispersion quality of samples for future work in quantifying the effects of particle size in nanocomposites through photoluminescence spectroscopy.