title: A method to obtain a well-defined fraction of respirable para-aramid fibers.
abstract: We developed a preparation method to obtain respirable-sized fractions of para-aramid fibers. The procedure, based on floatability, consists of stirring and subsequent settling of p-aramid pulp in distilled water. Two distinct phases are obtained, with small fibers in the upper part of the suspension, which represents about 33% of the total volume. Optimal results were obtained when 2.0 g pulp was stirred for 15 hr in 800 ml distilled water containing 0.125% ethanol and settled for 5 hr. The mass yield ranged between 0.4 and 0.6%, more than 90% of the particles had an aspect ratio > or = 3:1. The mean fiber length was about 6 microns, and the mean fiber diameter was about 0.4 microns as determined by transmission and scanning electron microscopy. The number of fibers obtained was 4 x 10(6) fibers/micrograms under our standard conditions.
authors.affiliation: Laboratoire de Pathologie Cellulaire et Moléculaire de l'Environnement, INSERM U139, 94010 Créteil, France.
authors.forename: R P
authors.initials: RP
authors.lastname: Schins
authors.forename: A
authors.initials: A
authors.lastname: Gaudichet
authors.forename: M C
authors.initials: MC
authors.lastname: Jaurand
mesh_terms: D005591:Chemical Fractionation; D006801:Humans; D008854:Microscopy, Electron; D008855:Microscopy, Electron, Scanning; D011108:Polymers / Q000138:chemical synthesis*; D012119:Respiration / Q000187:drug effects
chemical_list: C039578:Kevlar Aramid fibers; D011108:Polymers