Body Armor Fit For A Superhero
It seems crazy, Robert R. Schiller admits: the notion that you could shield yourself from bullets, shrapnel, and knives by donning the equivalent of a wet suit. But by early next year the president and chief operating officer of Armor Holdings Inc. (AH ) aims to be selling what he describes as "liquid armor" -- garments constructed from layers of tough fibers and fluid polymers -- to prison guards. By the end of 2007, he hopes, police and maybe soldiers will begin wearing the company's new protective gear as well. For the corrections market in particular, Schiller says, "it has the potential to be a breakthrough product."
Today's versions of body armor are composed mostly of 20 to 30 layers of synthetic fibers. And while there is no question the death toll for American troops in Iraq would be far higher without it, the gear is bulky and can't stop high-velocity bullets, for example, or all bomb fragments. Even as DuPont (DD ) was field-testing the original Kevlar jackets in the early 1970s, researchers were hunting for lighter, tougher ballistic fabrics. Since then, companies have investigated a chemist's kit of exotic materials, from cloned spider silk -- a wonder of lightness and strength -- to newfangled sheets of carbon nanotubes that are among the toughest structures in nature. Israeli researchers at one company, ApNano Materials Inc. in New York, have shown off a breastplate of nanometals said to be five times as strong as steel.
Armor Holdings' product is different from all of the above. Developed by Norman Wagner, a professor of chemical engineering at the University of Dela-ware's Center for Composite Materials, it's a mix of polyethylene glycol, a polymer found in laxatives and other consumer products, and nanobits of silica, or purified sand. Together they produce a "sheer-thickening liquid" that stiffens instantly into a shield when hit hard by an object. It reverts to its liquid state just as fast when the energy from the projectile dissipates.
LIKE PEANUT BUTTER
Initially, Wagner and his collaborators envisioned armor that could be spread on a person, almost like peanut butter on bread, says Eric Wetzel, a researcher at the Army Research Laboratory in Aberdeen, Md. But in tests co-sponsored by the Army Lab, they found that the materials worked best when painted on Kevlar in ultrathin coats. By holding the fibers tight like a flexible glue, the compound spreads out the impact of a blow better than fibers alone. "The search in the past has been for stronger and stronger filaments," says Wetzel. "We've tried to change how the fabric interacts with the projectile."
The liquid has other pluses. It's lighter than Kevlar and other widely used fabrics. That means Armor Holdings' new vests, in which the substance would be sandwiched between layers of ballistic fibers, might be lighter than current versions, which weigh four pounds or more. It also should be cheaper to manufacture, says Schiller. The Jacksonville (Fla.) company wants to continue to sell entry-level garments for $500 to $600.
Any minuses? No one knows yet how well the material will hold up after years of wear and tear.
Armor Holdings, which bought the rights to Wagner's discovery last February, pulls in the bulk of its $1.64 billion in annual sales from selling vehicle armor to the U.S. Army. While liquid armor seems tailor-made for combat personnel or police, the company is initially targeting prisons because the fabric resists punctures. That means it can protect guards from stabbings, something even a top-of-the-line bulletproof vest can't do.
By Michael Arndt