Fiberglass is a hybrid material composed of a flexible cloth mesh “matrix” that’s been soaked in a liquid resin. This gooey matt is then formed, pressed, and baked. The result can be a flat panel, the hull of a boat, a knee pad, a helmet, the dashboard of a race car, the shaft of a golf-club–almost anything. By using bullet resistant synthetics (similar to the DuPont™ Kevlar® fiber cloth in a bullet proof vest) for the supporting fiber matrix, fiberglass makers can craft panels capable of stopping bullets.
BRINGING CARBON NANOTUBES TO BULLET RESISTANT FIBERGLASS
The most common shape for bullet resistant fiberglass is a large quarter-inch thick panel. A single bullet resistant fiberglass panel of this type will stop a 9mm bullet. Stack up two (for a half-inch thick layer) and you can stop a 44 Magnum. Add another sheet to stop more energetic bullets from AK-47s or M16s, and so on.
A fabric woven from super strong single-walled carbon nanotubes would be an excellent candidate for the matrix supporting an advanced, paper-thin blast and bullet resistant fiberglass panel. “Carbon fiber” has long been used as the supporting mesh in high-performance fiberglass, and carbon nanotubes are already regularly integrated into the carbon fiber matrix used in the fiberglass shafts of high-end golf clubs and baseball bats.
OBSTACLES TO PAPER-THIN BULLET RESISTANT FIBERGLASS
But practical bullet proof experts don’t think you’ll be seeing ballistic playing cards any time soon. Total Security Solutions vice president Jim Richards is quick to point out that “everyone wants to go lighter, thinner, and more flexible, and yet stop bullets. Anything like that can be done with the technologies and materials that are out there today, it’s just that very few people besides the federal government want to spend the money for it.”
As it turns out, weaving fabric from carbon nanotubes is trickier than it sounds. The tubes themselves are millions of times longer than they are wide–but since they are just a few atoms wide, being “millions of times longer” still amounts to just a few centimeters. And carbon nanotubes–much like nylon–are especially good at shearing each other. Subsequently, yarns spun from individual carbon nanotubes tend to lack the qualities found in individual fibers: the many crossing points create millions of tiny stress points that, when added together in a real-world macro-scale impact, cause the fibers to saw through each other.
In 2010 Chinese researchers had a breakthrough with carbon nanotubes, when they constructed durable macro-scale fibers by flooding their carbon nanotube yarn with a plastic filler–a process not so different than how fiberglass is made. They’ve taken a big step closer to paper-thin, flexible carbon nanotube bullet resistant fiberglass. Now if they can just keep the price down.