Silane functionalization effects on dispersion of alumina nanoparticles in hybrid carbon fiber composites.

Hybrid carbon fiber reinforced polymer composites are a new breed of materials currently being explored and characterized for next-generation aerospace applications. Through the introduction of secondary reinforcements, such as alumina nanoparticles, hybrid properties including improved mechanical properties-fracture toughness, for example-and stress-sensing capabilities can be achieved. However, problems with manufacturing can arise resulting from the inherent variability of the manufacturing techniques along with the tendency for the nanoparticles to agglomerate. Photoluminescence spectroscopy is used to investigate the effects of adjustments to manufacturing processes and silane functionalization on particle dispersion and sample consistency between samples of the same type. This work finds that application of surface treatments on the nanoparticles improved their dispersion, with the reactive treatment providing for the most consistency among samples. Improvements to dispersion and increased consistency resulting from specific changes in manufacturing processes were shown numerically. Findings provide a manufacturing recommendation to achieve optimum dispersion and mechanical properties of the composite.

Quantifying Alumina Nanoparticle Dispersion in Hybrid Carbon Fiber Composites Using Photoluminescent Spectroscopy.

Composites modified with nanoparticles are of interest to many researchers due to the large surface-area-to-volume ratio of nano-scale fillers. One challenge with nanoscale materials that has received significant attention is the dispersion of nanoparticles in a matrix material. A random distribution of particles often ensures good material properties, especially as it relates to the thermal and mechanical performance of composites. Typical methods to quantify particle dispersion in a matrix material include optical, scanning electron, and transmission electron microscopy. These utilize images and a variety of analysis methods to describe particle dispersion. This work describes how photoluminescent spectroscopy can serve as an additional technique capable of quickly and comprehensively quantifying particle dispersion of photoluminescent particles in a hybrid composite. High resolution 2D photoluminescent maps were conducted on the front and back surfaces of a hybrid carbon fiber reinforced polymer containing varying contents of alumina nanoparticles. The photoluminescent maps were analyzed for the intensity of the alumina R1 fluorescence peak, and therefore yielded alumina particle dispersion based on changes in intensity from the embedded nanoparticles. A method for quantifying particle sedimentation is also proposed that compares the photoluminescent data of the front and back surfaces of each hybrid composite and assigns a single numerical value to the degree of sedimentation in each specimen. The methods described in this work have the potential to aid in the manufacturing processes of hybrid composites by providing on-site quality control options, capable of quickly and noninvasively providing feedback on nanoparticle dispersion and sedimentation.