Dawud Tan Thesis defense of Ph.D, October 31, 2011

Tuning the Diameter Properties of Meltblown Fibers

Thesis defense of Ph.D. candidate Dawud Tan
Dept of Chemical Engineering and Materials Science
IPrime Microstructured Polymers Program

Advisor: Prof. and IPrime Director Chris Macosko
Co-Advisor: Prof. and CEMS Head Frank Bates

Monday, October 31, 2011
Walter Library 402, University of Minnesota

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Abstract
Melt blowing combines extrusion of molten polymer through small orifices with stretching of the hot extrudate by hot air jets thereby creating long fibers with small diameter. The possibilities of producing meltblown nanofibers (i.e. an average diameter, dav, < 1 μm) by modifying the: 1) processing parameters or 2) material properties are presented. While attempting to produce nanofibers with polybutylene terephthalate (PBT), the influence of processing parameters was studied by varying the air and polymer flow rates and combining the effects using Γ, the ratio of air and polymer mass fluxes. Moreover, at supersonic conditions (high air flow rates or high Γ values), the influence of a Laval nozzle (converging-diverging nozzle) was investigated. The effect of material properties, specifically elasticity, was investigated by melt blowing different polystyrene (PS) blends containing low and high molecular weight (MW) PS.