Spider webs that are 10 times tougher than the best synthetic fibres and stronger than steel could soon be part of bulletproof vests, bridge cables and car bodies - when scientists learn how to spin them.
Researchers at the University of Washington and the U.S. Army have fabricated the material that makes up the silk of a common Florida spider and discovered clues about its structure that they believe will allow them to reproduce the silk and its extraordinary properties."Nature makes a lot of interesting materials, and we are just beginning to learn how to use them," said Christopher Viney, assistant professor of bioengineering and a metallurgist at the University of Washington.
Materials engineers are constantly searching for versatile, high-performance fibres that are easy to make, lightweight, strong and stiff enough to handle large loads and tough enough to absorb the energy of an impact.
Natural silk from spiders, silkworms and flies meets these criteria, but "farming" silk from them would not be efficient. The scientists have studied the Nephila clavipes or orb-weaving spider's dragline silk, one of about five kinds of silk that spiders produce.
It is the material a spider constantly secretes as it moves along and makes up the frame of the web on which the spider then constructs a sticky spiral to trap insect prey.
Scientists at the U.S. Army Research, Development and Engineering Center in Natick, Mass., have artificially produced the silk through duplicating the chemistry of the protein called fibroin that makes up the silk. But they learned that the special properties of the silk are based not only on the chemical composition of the material but also on the way spiders convert the molecules into fibre.
Dr. Viney's discovery, recently published in the British journal Nature, is that the natural silk secretions are in liquid crystal state. When secreted, the molecules are spontaneously aligned in chains called polymers in a specific formation and remain uniform to give the material its properties when dry.
He said the structure of the molecules in the liquid silk could be duplicated by fibre-processing machinery similar to that used to make materials such as rayon and Kevlar. Kevlar, a fibre used for its resilience in items from bulletproof clothing to boat hulls and armored vehicles, was invented in 1965 and is marketed by Du Pont Co. of Wilmington, Del.
Dr. Viney said the silk has 10 times the toughness of Kevlar and could replace it in many instances, but it may not be suitable for some applications, such as in areas where there are high temperatures.
"There are times when you will want to use Kevlar, times when you will want to use steel and times when you will want to use spider webs,' " he said.
He said he wants to study other silk-spinning organisms, such as a tiny fly larva that tethers itself in fast-moving rivers. Meanwhile, more can be learned about how spiders, whose spinnerets date back 380 million years in fossil records, spin their webs.
"Spiders still have the drop on us," Viney said. "Who knows? Maybe we can improve upon them." Distributed by Scripps Howard News Service