U.S. Army Soldier Systems Center-Natick
Public Affairs Office
Natick, MA 01760-5012
Contact: Chief, Public Affairs Office
Date: January 12, 2001
New Suit Helps Block Chemical and Biological Agents
NATICK, Mass. -- Just 25 microns thick, the selectively-permeable membrane found in the Chemical Biological Protective Field Duty Uniform resembles plastic wrap, yet it's a potent barrier against weapons of mass destruction.
The membrane replaces carbon. Variations of carbon-composed materials have been manufactured since chemical weapons were used in World War I. Carbon works, but it has several drawbacks.
"Carbon acts like a sponge," said Quoc Truong, a physical scientist at the Natick Soldier Center's Individual Protection Directorate. "When it reaches its holding capacity, it's no good. In heavy contamination, soldiers would have to carry extra suits to change into."
Heft is another setback. With the cellulose-based selectively-permeable membranes, the suit weighs nearly half as much as the Joint Service Lightweight Integrated Suit Technology (JSLIST) overgarment, the military's most modern protective suit. Instead of absorbing, the membranes block all known liquid, aerosol and vapor agents. At the same time, the polymer-based membrane allows moisture vapor from sweat to escape and evaporatively cool the body. A protective overgarment becomes unnecessary, although this suit would not become the regular duty uniform, said Truong. The regular Battle Dress Uniform is still more comfortable than any protective suit.
Truong compared the filtering and blocking process to shaking a woven basket filled with sand and marbles. The "marbles" represent chemical or biological molecules while the "sand" represents water molecules. The membrane is sandwiched between the inner liner and outer layer of either a nylon or heavier Nomex/Kevlar fabric. Because a tear in the fabric would render the suit ineffective, extra attention was focused on creating an abrasion and puncture-resistant material.
Extensive laboratory testing at Natick, the Edgewood Chemical Biological Center at Aberdeen Proving Grounds, Md., and Dugway Proving Grounds, Utah, proved the reliability of the material. In May 1999, soldiers at Fort Lewis, Wash., tested prototype membrane suits along with the JSLIST for comfort. In June, Marines tested the uniform for durability.
Truong said Hawaii was used as the test site because of the harsh environment with sharp surfaces. Marines successfully practiced amphibious assaults with the waterproof uniform.
"Soldiers like them very, very much," said Truong. "You do sweat, but it's much less than with a (Battle Dress Uniform) and JSLIST. Its light weight adds to the perception of comfort."
Besides being worn over the duty uniform, previous versions of chemical biological protective ensembles consisted of a jacket, pants, and rubber gloves and boots. The Chemical Biological Protective Field Duty Uniform covers everything from head to toe. The only piece missing is the protective mask.
A heavy-duty water and vaporproof zipper with thick, rubbery black plastic to form a tight seal opens at the front. Users step into the pant legs with "feet," slide their arms into the sleeves that have protective gloves attached to them, and close the zipper. The feet and gloves offer a seamless seal from the neck down. From the neck up, after the user dons the protective mask, the front flap with a rubberized brim slips snugly around the mask face. Then the back flap joins the front flap with a zipper closing across the head from ear to ear.
Overboots are unnecessary. Troops slip their covered feet directly into their combat boots. Selectively permeable gloves will replace the currently used butyl rubber gloves, which would ordinarily fill with sweat after a short wear time. Directly above each glove is another zipper opening to allow troops to take out their hands when dexterity is required.
Adjustable straps at each side of the waist can be fastened to provide a closer fit. A pocket on the left sleeve is slanted for easy reach. The front zipper conveniently opens from both ends with two sliders to allow users to don and doff the garment, and also take care of bodily functions. The thin, flexible material is easy to launder and uses less package volume.
Applications beyond the military include police and fire departments involved with domestic terrorism preparedness, medical employees who are exposed to bacteria and viruses, and industrial workers, who may be exposed to industrial chemicals, insecticides and pesticides. Truong said federal law enforcement agencies are preparing to test a modified-version of the suit to see how they might benefit from it.
Cellulose-based selectively-permeable membrane technology was developed with the help of Acordis Research GmbH, Obernburg, Germany. W.L. Gore and Associates, Inc. in Maryland developed its amine-based selectively permeable membrane with Natick's guidance.
The final contract was awarded to Acordis Research to develop a selectively-permeable coating for seamless glove application, while Texplorer is working with Natick to convert cellulose-based selectively-permeable fabric laminate to garments for human testing and evaluation.
Natick is part of the U.S. Army Soldier and Biological Chemical Command (SBCCOM). For more information about SBCCOM or the Soldier Systems Center (Natick), please visit our website at http://www.sbccom.army.mil.
This page last updated on 20 December 2001
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