title: Exposures to nanoparticles and fibers during injection molding and recycling of carbon nanotube reinforced polycarbonate composites.
abstract: In this study, the characteristics of airborne particles generated during injection molding and grinding processes of carbon nanotube reinforced polycarbonate composites (CNT-PC) were investigated. Particle number concentration, size distribution, and morphology of particles emitted from the processes were determined using real-time particle sizers and transmission electron microscopy. The air samples near the operator's breathing zone were collected on filters and analyzed using scanning electron microscope for particle morphology and respirable fiber count. Processing and grinding during recycling of CNT-PC released airborne nanoparticles (NPs) with a geometric mean (GM) particle concentration from 4.7 × 103to 1.7 × 106particles/cm3. The ratios of the GM particle concentration measured during the injection molding process with exhaust ventilation relative to background were up to 1.3 (loading), 1.9 (melting), and 1.4 (molding), and 101.4 for grinding process without exhaust ventilation, suggesting substantial NP exposures during these processes. The estimated mass concentration was in the range of 1.6-95.2 μg/m3. Diverse particle morphologies, including NPs, NP agglomerates, particles with embedded or protruding CNTs and fibers, were observed. No free CNTs were found during any of the investigated processes. The breathing zone respirable fiber concentration during the grinding process ranged from non-detectable to 0.13 fiber/cm3. No evidence was found that the emissions were affected by the number of recycling cycles. Institution of exposure controls is recommended during these processes to limit exposures to airborne NPs and CNT-containing fibers.
authors.affiliation: Department of Work Environment, University of Massachusetts Lowell, Lowell, Massachusetts, USA.|School of Occupational Health and Safety, Suranaree University of Technology, Nakhon Ratchasima, Thailand.
authors.forename: Pongsit
authors.initials: P
authors.lastname: Boonruksa
authors.affiliation: Department of Work Environment, University of Massachusetts Lowell, Lowell, Massachusetts, USA.
authors.forename: Dhimiter
authors.initials: D
authors.lastname: Bello
authors.affiliation: Department of Plastics Engineering, University of Massachusetts Lowell, Lowell, Massachusetts, USA.
authors.forename: Jinde
authors.initials: J
authors.lastname: Zhang
authors.affiliation: Department of Mechanical &Industrial Engineering, Northeastern University, Boston, Massachusetts, USA.
authors.forename: Jacqueline A
authors.initials: JA
authors.lastname: Isaacs
authors.affiliation: Department of Plastics Engineering, University of Massachusetts Lowell, Lowell, Massachusetts, USA.
authors.forename: Joey L
authors.initials: JL
authors.lastname: Mead
authors.affiliation: Department of Work Environment, University of Massachusetts Lowell, Lowell, Massachusetts, USA.
authors.forename: Susan R
authors.initials: SR
authors.lastname: Woskie
mesh_terms: D000395:Air Pollutants, Occupational / Q000032:analysis*; D004391:Dust / Q000032:analysis; D004784:Environmental Monitoring / Q000379:methods; D006801:Humans; D019570:Inhalation Exposure / Q000032:analysis; D046529:Microscopy, Electron, Transmission; D057139:Nanofibers / Q000032:analysis*; D053758:Nanoparticles / Q000032:analysis* / Q000737:chemistry; D037742:Nanotubes, Carbon / Q000032:analysis* / Q000737:chemistry; D016273:Occupational Exposure / Q000032:analysis*; D010316:Particle Size; D011076:Polycarboxylate Cement; D059027:Recycling; D012044:Regression Analysis
chemical_list: D000395:Air Pollutants, Occupational; D004391:Dust; D037742:Nanotubes, Carbon; D011076:Polycarboxylate Cement; C005506:polycarbonate