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VOC Emissions and Formation Mechanisms from Carbon Nanotube Composites During 3D Printing(poster)
Citation:
Potter, P., S. Al-Abed, D. Lay, AND S. Lomnicki. VOC Emissions and Formation Mechanisms from Carbon Nanotube Composites During 3D Printing(poster). ACS Annual Spring Meeting, Orlando, Florida, March 31 - April 04, 2019.
Impact/Purpose:
Polymers used in 3D printing are known to emit hazardous materials when heated. While the emissions from pristine polymers and some filaments have been studied, many filaments contain additives that may influence their hazardous emissions. For example, carbon nanotubes (CNTs) are added to some filaments to confer structural and electrical properties and are likely to interact with volatile organic compound (VOC) emissions. This research used a commercially-available CNT-containing 3D printer filament to investigate the effect of CNTs on VOC emissions during the printing process. While the presence of CNTs caused a slight overall decrease in the total VOC emissions, there was a shift towards more hazardous compounds being emitted. These findings should influence future studies on 3D printer emissions to include additives such as CNTs, metals, and dyes. These methodologies may be used by EPA's Chemical Safety and Pollution Prevention (OCSPP), Consumer Protection and Safety Commission (CPSC), and National Institute of Occupational of Safety and Health.
Description:
The increase in number of 3D printers found in households and workplaces has led to a growing concern over their hazardous emissions. One category of emissions from fused deposition modelling (FDM) printers consists of volatile organic compounds (VOCs). While VOC emissions from common pristine polymers have been investigated, many 3D printer filaments utilize additives to achieve various aesthetic and structural properties that may influence VOC emissions. One such additive is carbon nanotubes (CNTs), which are used to apply conductive properties to printed objects. A commercially-available, 3D printer nanocomposite filament of carbon nanotubes (CNTs) and acrylonitrile-butadiene-styrene (ABS) was analyzed with respect to its VOC emissions during simulated FDM and compared with an ABS filament without CNTs. VOC emissions were quantified and characterized under a variety of conditions to simulate the thermal degradation that takes place during FDM. Increasing residence time and temperature resulted in significant increases in VOC emissions and oxygen content of the reaction gas influenced the VOC profile. In agreement with other studies, the primary emitted VOC was styrene. Multiple compounds are reported in this work for the first time as having formed during FDM, including: 4-vinylcyclohexene, isopropylbenzene, benzaldehyde, and 2-phenyl-2-propanol. The presence of CNTs in the filament influenced VOC yields and product ratios and suggests a reaction mechanism involving an adsorbed styrene species. The present study has identified an increased risk associated with thermal degradation of CNT nanocomposites used in 3D printing.