Large-Format Additive Manufacturing and Machining Using High-Melt-Temperature Polymers. Part II: Characterization of Particles and Gases

摘要

Extrusion of high-melt-temperature polymers on large-format additive manufacturing(LFAM) machines releases particles and gases, though there is no data describing theirphysical and chemical characteristics. Emissions from two LFAM machines were monitoredduring extrusion of acrylonitrile butadiene styrene (ABS) and polycarbonate (PC) polymers aswell as high-melt-temperature Ultem (poly(ether imide)), polysulfone (PSU), poly(ethersulfone) (PESU), and polyphenylene sulfide (PPS) polymers. Filter samples of particles werecollected for quantification of elements and bisphenol A and S (BPA, BPS) and visualization ofmorphology. Individual gases were quantified on substance-specific media. Aerosol samplingdemonstrated that concentrations of elements were generally low for all polymers, with amaximum of 1.6 mg/m~3 for iron during extrusion of Ultem. BPA, an endocrine disruptor, wasreleased into air during extrusion of PC (range: 0.4 ± 0.1 to 21.3 ± 5.3 μg/m~3). BPA and BPS (also an endocrine disruptor) werereleased into air during extrusion of PESU (BPA, 2.0−8.7 μg/m~3; BPS, 0.03−0.07 μg/m~3). Work surfaces and printed parts werecontaminated with BPA (<8−587 ng/100 cm~2) and BPS (<0.22−2.5 ng/100 cm~2). Gas-phase sampling quantified low levels ofrespiratory irritants (phenol, SO_2, toluene, xylenes), possible or known asthmagens (caprolactam, methyl methacrylate, 4-oxopentanal, styrene), and possible occupational carcinogens (benzene, formaldehyde, acetaldehyde) in air. Characteristics ofparticles and gases released by high-melt-temperature polymers during LFAM varied, which indicated the need for polymer-specificexposure and risk assessments. The presence of BPA and BPS on surfaces revealed a previously unrecognized source of dermalexposure for additive manufacturing workers using PC and PESU polymers.