Browsing by Author "Dr. Roger L. Barker, Committee Co-Chair"

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    Analysis of Factors Influencing Methyl Salicylate Adsorption on Textile Skin Simulants
    (2009-12-22) Gladish, Justin Lee; Dr. Peter J. Hauser, Committee Member; Dr. Roger L. Barker, Committee Co-Chair; Dr. Keith R. Beck, Committee Co-Chair
    This research studied adsorption of methyl salicylate (MeS) onto knit textile structures. It examines the feasibility of using knit materials as a skin simulant in Man In Simulant (MIST) protocols. MeS is used as a simulant for toxic chemical agents. Knit fabrics were studied because of their conformability to mannequin limbs, and the potential for using these materials to enhance the correlation between mannequin and human garment tests of chemical resistance of vapor protective ensembles. Experiments were conducted at different MeS concentration levels, airflows, and with moisture preconditioned fabric. Fabrics made of protein, cellulosic, and synthetic fibers were studied to provide a range of comparison among hydrophilic/phobic fiber types. This research showed that the fiber composition and construction of knit fabric are the primary determinants of MeS adsorption. Knit materials made with protein-based fabrics, such as wool and silk, adsorbed more MeS than do knit materials made with nylon or cotton. Moisture preconditioning, designed to simulate adsorption of sweat on a mannequin, dramatically increases the adsorption of MeS. The target MeS skin adsorption was calculated based on the theoretical mass adsorbed on an uncovered Natick PAD during MIST exposure. The target mass calculated was 0.6 mg/fabric swatch (100cm2) of MeS. Preconditioned, moist, silk and nylon double knit adsorbed close to the MeS target mass with an approximate adsorption of 0.74 and 0.64 mg MeS respectively.
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    Performance Evaluation of Chemical Protective Clothing Materials under Dynamic Mechanical Deformation
    (2005-07-13) Shiels, Brian Patrick; Dr. Juan P. Hinestroza, Committee Chair; Dr. Roger L. Barker, Committee Co-Chair; Dr. Morteza G. Khaledi, Committee Member; Dr. Orlando J. Rojas, Committee Member
    This thesis presents a comprehensive assessment of testing methodologies currently used for evaluating the performance of protective clothing materials. Special emphasis is placed on highlighting the inadequacy of such test methods and their lack of correlation with real life scenarios which may introduce mechanical deformation. ASTM F23 standardized rubber sheets were used to evaluate the sorption, permeation and penetration behavior of the samples when exposed to a standardized liquid challenging agent. 2-Chloro-1,3-butadiene (neoprene) was used as the standard chemical protective clothing material and liquid acetone was selected as the standard challenging agent. The dynamic mechanical properties of the samples were assessed via creep and stress relaxation testing techniques using customized submersion clamps. Quantitative agreement between sorption and permeation experimental data validated the concept that diffusion was the rate-limiting step for the transport of acetone through neoprene rubber. Creep and stress relaxation experiments illustrated a strong time dependency of the storage and loss modulus of the neoprene samples when exposed to the challenging agent. The Young's modulus of the standard material was also found to be a decreasing function of the number of loading-unloading cycles highlighting the effect of mechanical deformation of the barrier properties of protective clothing materials. Potential improvements to existing testing methodologies are proposed and discussed in detail.