Colorado researchers produce a better chemical warfare suit
Conventional butyl rubber is blended with polymerizable liquid crystal; water transfer rates and permeability substantially improved, allowing for lighter and safer suits; other applications include filters for brine and contaminated water
American soldiers have so far been lucky in avoiding exposure to chemical weapons, but this has been only a small consolation to the troops who have had to drill endlessly in heavy protective clothing — often under the sweltering Arabian sun. Previously, these chemical warfare suits came in two varieties: a full-body affair made of cross-linked butyl rubber that also required an attached breathing appararatus, or one fortified with activated carbon. Both were unpleasant, with the former being so hot it had on occassion led to heatstroke and death; and the latter being extremely heavy and not practical for heavy combat. Two Colorado scientists now say they have made important changes to butyl rubber that could lead to safer and more comfortable chemical protection gear.
Butyl rubber, said University of Colorado at Boulder chemist Douglas L. Gin, “is a really good barrier, but it’s really good both ways” — meaning that it is as good at keeping heat and sweat in as it is at keeping dangerous substances out. Gin and research partner Brian Elliott of Wheat Ridge, Colorado-based TDA Research
have managed to tweak the rubber for greater water transport by cross-linking it to make a three-dimensional network, which, Gin said, “makes it more chemically, mechanically and thermally robust.”
“The crux of our whole technology is we can take conventional commercial butyl rubber and, by blending it with our polymerizable liquid crystal, we can actually make these water conduits in there,” said Gin. “And depending on the type of liquid crystals, we can control the dimensionality from one-dimensional cylinders or tubes to the much more effective interconnected 3-D water manifold system.”
Tests of the material revealed a water vapor transport rate for a four-micrometer-thick film to be four times the minimum acceptable rate by the military and 300 times that of the standard butyl rubber. It is also about 30 percent less permeable, making it more effective for protection against a chemical agent. Gin and Elliott are now working to create even thinner swaths of butyl rubber, and they see other applications of the material, including as a filter for solutions such as brine to contaminated water.
-read more in this Scientific American report
