Fibers ultrafine

A special use for meltblown olefin fiber is in filtration media such as surgical masks and industrial filters (78). The high surface area of these ultrafine filament fibers permits preparation of nonwoven filters with effective pore sizes as small as 0.5 p.m. 

Fig. 2. Ultrafine fibers are produced by spinning bicomponent or biconstituent polymer mixtures, highly stretching such products to ultrafine deniers, and extracting or otherwise removing the undesked matrix carrier to release the desked ultrafine fibers (30). For example, spinning polyester islands in a matrix of polystyrene and then, after stretching, dissolving the polystyrene to leave the polyester fibers cospinning polyester with polyamides, then stretching,...

Ultrafine carbon fibers Non-toxic burn-rate modifiers for cast DB propellants in the absence of lead salts [248]. 

Neidert, J.B., and Askins, R.E. (1994) Castable DB propellant containing ultrafine carbon fiber as a ballistic modifier. US Patent 5,372,664. 

The collection efficiency of a fiber is defined as the ratio of the number of particles striking the fiber to the number which would strike it if the streamlines were not diverted [Dorman, 1966]. For particles with dp > 1 pm, the particles are collected primarily by inertial impaction and interception. Collection by diffusion is only important for submicron particles. In the following, we only discuss the methodology of collection efficiency by interception. Details about the filtration of fine and ultrafine powders or granular filtration in general can be found in Davies (1973), Fuchs (1964), Dickey (1961), Matteson and Orr (1987), and Tien (1989). 

The sol-gel process involves the transition of a system from a liquid "sol" (mostly colloidal) into a solid "gel" phase (11). By applying this methodology, it is possible to fabricate ceramic or glass materials in a wide variety of forms ultrafine or spherical-shaped powders, thin film coatings, ceramic fibers, microporous inorganic membranes, monolithic ceramics and glasses, or extremely porous aerogel materials. 

In GAS, a compressed gas acting as antisolvent is dissolved in the solution of a nonvolatile component with gas contents in the order of equimolar mixtures. This causes a volumetric expansion and hence a remarkable reduction in solvent power. Consequently, precipitation or crystallisation of the solute occurs, leading to ultrafine particles and fibers in the micrometer range. Furthermore, the precipitates e g. pharmaceutical products are purified while impurities remain in solution. 

Figure 31 shows SEM photographs of ultrafine CTA fibers electrospun Irom different ratios of MC/ EtOH (90 / 10, 85/ 15, and 80/20 v/v). All ultrafine CTA fibers were... 

Figure 31. SEM images of ultrafine CTA fibers electrospun using different volume ratios of MC/EtOH (a) 90/ 10, (b) 85/ 15, and (c) 80/ 20 [81].

ID Norris, MM Shaker, FK Ko, AG Macdiarmid. 2000.Electrostatic fabrication of ultrafine conducting fibers polyaniline/polyethylene oxide blends. Synthetic MetoA,l 14(2).pp. 109-114. 

FIG. 21-13 Diagram of Leeds and Northrup Ultrafine Particle Size Analyzer (UPA), using fiber optics in a backscatter setup. 

Macromolecular Rapid Communications 25, No. 18,24th Sept.2004, p. 1632-7 PREPARATION OF ANTIMICROBIAL ULTRAFINE CELLULOSE ACETATE FIBERS WITH SILVER NANOPARTICLES Son W K Youk J H Lee T S Paik W H Chungnam,National University Inha,University... 

Ultrafine n. [Laurel Industries] Sub-mioon sized antimony oxide flame retardant for thermoplastics, thermosets, synthetic fibers as catalyst feu PET mfg. 

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