Locating Graphene Oxide Derivatives at Low Loadings in Fiber Reinforced Polymer Composites using Raman Spectroscopy

Incorporating graphene oxide (GO) nanofillers into polymers is a viable technique to improve mechanical properties at very small loadings. The addition of as little as 0.04 % by mass of surface modified GO in unsaturated polyester resin (UPR) can increase fracture toughness by as much as 50 % without lowering other mechanical properties. Rapid characterization of the nanofiller dispersion is crucial since property enhancements are strongly correlated to a uniform distribution of filler. This has proven difficult for high aspect ratio nanofillers in a polymer composite, and is almost impossible for fiber reinforced composites when the mass fraction of nanofiller is below 1 % by mass. Micro-Raman spectroscopy provides rapid, detailed, non-destructive measurements, and is a powerful technique to qualitatively identify nanoscale carbon-based materials. In this work, modified GO particles are located in an UPR matrix at 0.04 % by mass via spatial mappings of Raman spectra. The non-homogenous dispersion of the GO is clear in these mappings and likely enables the detection. This technique is also extended to composites reinforced with glass fibers where we measure GO particles near fiber interfaces. This robust work provides a significant advancement for guiding large scale production.