VOC Emissions and Formation Mechanisms from Carbon Nanotube Composites during 3D Printing

Abstract

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 fused deposition modelling (FDM) and compared with a regular ABS filament. 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 4vinylcyclohexene and 2-phenyl-2-propanol. Our results show that printing 222.0 g of filament is enough to surpass the reference concentration for inhalation exposure of 1 mg/m 3 according to the EPA's Integrated Risk Information System (IRIS). The presence of CNTs in the filament influenced VOC yields and product ratios through three types of surface interactions: 1) adsorption of O 2 on CNTs lowers the available O 2 for oxidation of primary backbone cleavage intermediates, 2) adsorption of styrene and other VOCs to CNTs leads to surface-catalyzed degradation, and 3) CNTs act as a trap for certain VOCs and prevent them from entering vapor emissions. While the presence of CNTs in the filament lowered the total VOC emission under most experimental conditions, they increased the emission of the most hazardous VOCs, such as α-methylstyrene and benzaldehyde. The present study has identified an increased risk associated with the use of CNT nanocomposites in 3D printing.

3D-Printed Lab-on-a-Chip Diagnostic Systems-Developing a Safe-by-Design Manufacturing Approach

“…Another study that investigated the influence of nanofiller on FFF process emissions was conducted by Potter et al [110], reporting increased risks for such filament materials. The authors quantified and characterized VOC emissions of two commercial 3D printer filaments (ABS-CNT nanocomposite, ABS) in simulated FFF thermal conditions.…”

“…Interestingly, the presence of CNTs resulted in slightly reduced total VOC emissions under most experimental conditions, nevertheless increasing the emission of specific highly hazardous VOCs. It is also highlighted that emitted CNTs can present additional inhalation hazard as adsorption sites for VOCs [110].…”

Extending Cellulose-Based Polymers Application in Additive Manufacturing Technology: A Review of Recent Approaches

“…AM has expanded to various industries, including metal, ceramic, and medical applications, and the current focus of this technique is bioprinting cardiovascular application, which involves 3D-printed heart valves [ 20 , 21 , 22 , 23 ]. Various materials to be used in AM have been developed, such as polymers, metals, and composites; however, most of these materials are harmful to humans and the environment due to the release of volatile organic compounds [ 23 , 24 , 25 , 26 ].…”

Particle and volatile organic compound emissions from a 3D printer filament extruder

“…Available filament materials include acrylonitrile butadiene styrene (ABS), polylactic acid (PLA), nylon, high impact polystyrene (HIPs), polyvinyl alcohol (PVA) and others (Azimi et al, 2016). VOCs, and their associated filaments, that have been recorded include styrene (ABS), ethylbenzene (ABS, HIPs), benzaldehyde (ABS, PLA), acetaldehyde (ABS, PLA), caprolactam (PLA, nylon, HIPs), acetone (ABS, PLA), lactide (PLA) and many others (Azimi et al, 2016;Davis et al, 2019;Gu et al, 2019;Potter et al, 2019).…”

“…Emissions from FDM® 3D printers have been recorded for operating temperatures from 180 °C to 280 °C with higher temperatures producing higher levels of both particulates and VOC emissions (Byrley et al, 2019;Deng et al, 2016;Potter et al, 2019;Zhang et al, 2017). In addition, a wide variety of filament materials have been shown to release emissions, including ABS and PLA (Azimi et al, 2016;Davis et al, 2019;Vance et al, 2017).…”