LAUSR

Abstract Our study aims at a better understanding of the release process of graphene-related materials (GRMs) from epoxy composites during an abrasion process and the quantification of the released GRM fraction in the abraded particles. We investigated the GRM dispersion in epoxy-based composites using terahertz spectroscopy and determined the released exposed (freestanding and protruding) fraction of GRMs in the abraded powders. First, GRMs were labeled with lead and immersed into epoxy resin. Composites were produced by adding hardener and curing. Results from EDX-SEM (energy-dispersive X-ray-scanning electron microscopy) mapping and Raman spectroscopy mapping showed exposed GRMs on the surface of the abraded powders. In the first approach, we identified the released exposed GRM fraction by measuring the amount of detached lead ions from lead-labeled GRMs using inductively coupled plasma-optical emission spectrometry (ICP-OES). In the second approach, we employed Raman spectroscopy mapping as a semi quantitative method to assess the released exposed GRM fraction via determining the GRM surface coverage in the abraded powders. The results from the Raman intensity ratio maps are similar to those of the ICP-OES technique. The fractions of released exposed GRMs ranged from 18% to 92% depending on the type of GNP. Our study combines multiple qualitative, semi quantitative and quantitative methods to determine the released exposed GRM fraction and thereby facilitates exposure and risk assessment of GRM containing composites.