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VOCs and particulate matter emissions from 3D printing: Effect of filaments polymer composition and additives
Citation:
Al-Abed, S. AND S. Lomnicki. VOCs and particulate matter emissions from 3D printing: Effect of filaments polymer composition and additives. American Chemical Society Fall meeting, Chicago, IL, August 20 - 25, 2022.
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. The presence of additives may not only cause total VOC emissions but hazardous compounds being emitted during printing. 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 (NIOSH).
Description:
As applications for 3D printers grow, there is a growing concern regarding their hazardous emissions. One category of emissions from fused filament fabrication (FFF) printers consists of volatile organic compounds (VOCs). While VOC emissions from common pristine polymers have been investigated, these studies tend to focus on thermal degradation products that result directly from the polymer backbone. Many 3D printer filaments contain unreacted polymerization initiators or utilize additives to achieve various aesthetic and structural properties that may influence VOC emissions. A commercially available nanocomposite filament of carbon nanotubes (CNTs) and acrylonitrile-butadiene-styrene (ABS) was analyzed with respect to its VOC emissions during simulated FFF and compared with an ABS filament without CNTs. Increasing residence time and temperature resulted in significant increases in VOC emissions and oxygen content of the reaction gas influenced the VOC profile. The presence of CNTs in the filament generally lowered total VOCs but increased emission of more toxic species, such as alpha-methylstyrene. Three polylactic acid (PLA) filaments containing either copper, bronze, or stainless-steel particles were studied in addition to three carbon nanotube (CNT) filaments made from PLA, ABS, and polycarbonate (PC). In addition, the filament with stainless steel particles had a threefold increase in total VOCs compared to the copper and bronze particles. Two of three CNT-containing filaments emitted compounds that have not been reported before for PLA and PC. A comparison between certain emitted VOCs and their suggested maximum inhalation limits shows that printing as little as 20 g of certain filaments in a small, unventilated room can subject the user to hazardous concentrations of multiple toxic VOCs with carcinogenic properties (e.g., acetaldehyde, 1,4-dioxane, and bis(2-ethylhexyl) phthalate). In addition, preliminary results suggest the formation of surface-bound radical species known as Environmentally Persistent Free Radicals (EPFRs) during 3D printing. EPFRs form during interaction of certain organic species and metal oxides at elevated temperatures. EPFRs can generate reactive oxygen species in biological fluids and are a known inhalation hazard.