Strategies to Protect the Health of Deployed U.S. Forces Force Protection and Decontamination (1999) / Chapter Skim
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Appendix B: Textiles and Garments for Chemical and Biological Protection
Appendix B: Textiles and Garments for Chemical and Biological Protection
Pages 182-216
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From page 182... ...
As the battlefield environment becomes increasingly complex, we need to ask the fundamental question from time to time whether textile and garment manufacturing technology are keeping pace with current and projected demands. Do we have the fiber materials to meet specific needs?
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From page 183... ...
For example, a barrier to protect against a chemical warfare agent must be completely impermeable, which interferes with physiological protection requirements that demand permeability to prevent heat stress. This discussion is focused on CB protective textiles and garments.
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From page 184... ...
requirements and classifications of protective clothing for defense purposes but only briefly discussed CB textiles. The most relevant summary of the state of CB protective textiles was presented at an Industrial Fabric Association international conference in 1982 at which the threats of chemical warfare were described by Colonel Hidalgo of the U.S.
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From page 185... ...
This program resulted in a new experimental technique based on the finding that the liquid breakthrough resistance in fabric structures could be optimized by symmetric design of the fabric surface (Miller, 1986~. Considering the importance of fabric structures in CB protection, NRDEC also contracted with Drexel University, under the Textile Center of Excellence Program, to carry out a study on the feasibility of improving the performance of CB protective textiles by fabric engineering.
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From page 186... ...
The topics covered in this workshop included barrier mechanisms for liquid and vapor agents; the characterization of barrier effectiveness based on liquid transport properties; modeling the interaction of fabric structure and physiological responses; a review of textile materials and structures for chemical protection; water and oil repellents; design of chemical protective textiles; design of chemical protective clothing; human factors in protective clothing design; and reactive systems for protection and decontamination. The workshop concluded with a projection of future protective systems and the announcement by Dr.
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From page 187... ...
Such research funds as were available were committed to other higher priority projects, with virtually no funds being committed to further research in chemical protective clothing in the years thereafter. The clothing system adopted at that time was intended for ground soldiers, and more importantly it was intended to be used essentially in a defensive mode.
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From page 188... ...
However, almost all of them have one or more glaring deficiencies, which rule out their use as clothing items. In the protective clothing area, the problem is far more complex than the typical materials research problems, which can find their solutions in sciences such as physics, chemistry, metallurgy, and so forth.
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From page 189... ...
A selective barrier is desirable, and the basic protective overgarment system we adopted in 1970 achieves this by using activated carbon in sorptive matrix to filter out the agents. The carbon is contained in a polyurethane foam matrix, which, unfortunately, carries a number of penalties, not the least of which is the heat stress it produces.
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From page 190... ...
The overgarment existing today has this configuration: The outer shell consists of the 5-ounce nylon/cotton blended twill, the inner component, the so-called active part which contains the activated carbon impregnated into approximately a 90-mil polyurethane foam, has a liner, two-ounce nylon tricot. The bottom two layers are laminated together, and the top layer essentially floats and is put on as the garment is manufactured.
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From page 191... ...
Instead of the polyurethane foams other possible foams might have advantages, being more permeable, being substantive to the carbon, etc., so that the activity of the carbon may remain higher. Technology allows us to make hollow fibers into which we could put activated carbon powder.
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From page 192... ...
It is best to go around them again to repeat them, starting with carbon, putting carbon powder again into a textile material, whether it be embedded in the fiber or in a hollow fiber, trying to use carbon fibers in one form or another. Your approach of using reactive materials, whether they be, for example, ion-exchange resins, is more of the idealized situation that I just mentioned as a possibility.
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From page 193... ...
This is another material characteristic that would be desired not only for handwear but also for footwear and hood materials, which cover the head area. 193 The technical requirements for CB protective textiles described by Dr.
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From page 194... ...
nylon tricot warp knit structure. Reducing weight and bulk, improving durability, and reducing heat stress will require assessing the entire inventory of textile materials, including fibers, yarn, and fabric structures.
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From page 195... ...
The impermeable barrier approach was used for protective clothing until the mid-1970s. Currently, it is used only for gloves, boots, and other special applications intended for shorttime use, such as the suit, contamination avoidance, liquid protection (SCALP)
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From page 196... ...
Carbon powder can be in the form of foam, coated fibers, hollow fibers, or meltblown fibers. Activated carbon fibers can be used as nonwoven, flocked fabrics or laminated structures.
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From page 197... ...
197 In o (a to o Q (a .
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From page 198... ...
An integral part of the development of chemical protective clothing is the development of testing and evaluation methods for assessing the performance of chemical protective clothing under simulated conditions that are as realistic as possible. Tests for evaluating the effectiveness of barrier systems vary from simple small-scale swatch tests to full-scale field tests (NRC, 1997~.
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From page 199... ...
Therefore, spider silk has been selected as the model for the fiber of the future for soldier protection. Textile fibers are classified according to their geometry, chemical composition, or thermomechanical properties (Table B-5~.
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From page 201... ...
The first treatment of fibers as an engineering material was presented by Dewitt Smith in his ATSM Edgar Marburg Lecture (Dewitt Smith, 1944~. As the development of synthetic fibers continued, Harris and his associates at the Harris Research Laboratories compiled an impressive collection of physical and mechanical properties of textile fibers (Harris, 1954~.
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From page 202... ...
The fineness of the fiber has the most influence on the performance of CB protective textiles. Fiber diameters range from 20-26 microns for wool to 0.001 microns for electrospun fibers (Fukuhara, 1993~.
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From page 203... ...
Different functionalities can be introduced to the fibers (i.e., activated carbon imbedded fibers, hollow fibers filled with activated carbon, activated carbon overbraided with cotton, activated carbon-coated yarns, and reactive fibers) by texturing, polymer modification, special sizing, denier mixing, sludge mixing, coating, wrapping, and chemical treatment.
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From page 204... ...
Another innovation in Japanese industry is flexibility in manufacturing systems. The growth of the specialty fiber business prompted producers to increase the flexibility of their facilities.
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From page 205... ...
In another series of embodiments, pressurized water exiting from jets generates subdenier filaments by fibrillation) , forms nonwoven fabrics by fiber lacing, and propels fill yarns across warps on waterjet looms.
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From page 206... ...
Chemically bonded nonwoven fabrics are less bulky but tend to be paper-like and nonconformable. Because of the simplicity of processing and high productivity of nonwoven fabrics, industry has a strong incentive to use nonwoven structures for primary garment fabrics.
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From page 207... ...
Because of the broad range of possibilities, the performance maps are qualitative, rather than quantitative. Critical Properties The properties included in the performance maps reflect the basic requirements of CB protective textiles: (1)
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From page 208... ...
. As fiber diameter and yarn diameter increase, the structure tends to become more porous.
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From page 209... ...
Based on the general performance map, experimental evidence, and simulated results, we can conclude that fiber architecture and fiber diameter are very important in controlling the geometric and performance characteristics important for CB protective textiles. FUTURE DIRECTIONS The requirements for the next generation of CB protective garments
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From page 210... ...
diameter Porosity a: Cover factor Fiber diameter ~Surface texture cc A. Modular length o lo. Fiber mobility Volumininosty a: Fiber diameter Thickness ~ Fiber(yarn)
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From page 211... ...
Low Compressibility High Needle felt Spunlaced C,3 C,3 I Spunbonded Resin bonded | Film I Low Extensibility High Fiber diameter Permeability <= Fiber volume fraction con Cal P) Is ~Voluminosity Compressablllty cc Fiber stiffness Extensibility cc Fiber elongation Yarn linearity Thickness cc Strength x elongation Stiffness FIGURE B-8 Performance properties of nonwoven fibers.
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From page 212... ...
The capability of the U.S. defense industry to develop and field advanced CB protective textiles and garments will require the cooperative participation of research institutions as well as the fibertextile-garment industry.
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From page 213... ...
The strength of nanofiber fibers, however, is still far below that of conventional textile fibers. In addition, the technology of processing nanofibers in traditional textile machines is not well established.
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From page 214... ...
textile and garment industry will be dependent on foreign textile materials and machinery technology. If we wish to assess the readiness of the U.S.
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From page 215... ...
1985. Computer-Aided Design of Nonwoven Fabrics.
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From page 216... ...
1986. Design Criteria for Effective Chemical Protective Clothing with Asymmetric Transport Properties.
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