A study on the nanoparticle emissions into environment during mechanical drilling of polyester, polypropylene, and epoxy nanocomposite materials

Despite the beneficial effects on material properties in polymer nanocomposites, certain nanofillers have shown conceivable toxicity to humans and the environment. The use of these nanoparticles can be hazardous when human exposure is concerned. While studies have demonstrated nanoparticles to be released during machining, the influence embedded nanoparticles within commercial nanocomposites have on release during machining is yet to be understood. In this study, four groups of industrial nanocomposites incorporating seven different nanoparticles are investigated. The mechanical properties are investigated and an automated drilling methodology in which the background noise is eliminated is used for a process approach on the assessment of nanoparticle emissions. Real-time data are collected using a condensation particle counter, scanning mobility particle sizer spectrometer, a real-time fast mobility particle spectrometer (DMS50), and posttest analytical methods. Overall, 67% of the samples investigated exhibited a statistically significant increase and 17% displayed a statistically significant decrease on the emitted particle number concentration with the introduction of nanoparticles within the material. The nanoparticle release was observed to not be direction correlated to nanofiller concentration, but instead to the Young's modulus and polymer brittleness, or ductility property. The results identify a novel correlation between nanoparticle release and mechanical properties of polymer nanocomposites. The evidence presented contributes a significant implication on safety understanding and concerns of nanoparticle release from polymer nanocomposites during drilling.