Characterization of particulate matter in carbon-graphite/epoxy advanced composite material smoke.

The physical and chemical properties of the particulate fraction of carbon-graphite/epoxy advanced composite material (cgeACM) smoke were measured to address concerns regarding potential health hazards posed by the release of fibers during pyrolysis of this material. Filter, low-pressure cascade impactor, and electrostatic precipitator samples were collected from cgeACM smoke in which the aerosol concentration ranged from 0.20 to 5.39 g/m3. Fibers were found in the smoke among individual, spherical, or nearly spherical particles and chain aggregates. The fibers had a mean count diameter of 0.54 micron and an average length of 2.84 microns. However, fibers accounted for approximately 0.3% of the particles counted. The smoke aerosols (including fibers) had mass median aerodynamic diameters (MMAD) ranging from 1.4 to 1.9 microns with standard geometric deviations ranging from 1.6 to 1.8, and hence more than 88% of the particles were in the thoracic size range (MMAD < or = 4.0 microns). All particles were composed primarily of carbon, silicon, sulfur, and oxygen with traces of other metals. By comparison fibers were composed almost exclusively of silicon.