The step beyond Gore-Tex just might be clothing that warms you when it is cold and cools you when it is warm. But don't rush to place your order with L. L. Bean or Eddie Bauer just yet. Such a garment -- what you might call a heat-pump parka -- is at least a decade away.
However, it is one possible outcome of research being done by Tyrone L. Vigo, a textile expert with the US Department of Agriculture (USDA), and reported at the annual meeting of the American Chemical Society held here last week. Combining chemicals used in passive solar collectors with standard yarns, Dr. Vigo has managed to make cloth that absorbs and releases up to four times as much heat as ordinary fabric.
Dr. Vigo is not the first to make fibers whose thermal response varies with temperature. In 1971 J. P. Stevens Company obtained a patent for hollow fibers filled with a mixture of liquid and gas. As the temperature changed, more or less gas was released, altering the insulation value of the fiber. But Dr. Vigo's approach is simpler. He has taken a class of materials known as plastic crystals or organic alcohols and deposited them inside hollow fibers. This material absorbs and releases large amounts of energy without melting and resolidifying. These substances are nontoxic and inexpensive, he reports.
These results indicate that it is possible to make temperature-adaptable fabric that is effective in temperatures ranging from freezing to boiling.
Although clothing manufacturer Levi Strauss has expressed some interest in his work for use in ski wear, Vigo estimates it will take at least a decade before the fruits of his effort appear on department store racks. A nearer-term use may be in building insulation and solar-heated greenhouses.
First, there are a number of practical problems that must be overcome. Perhaps the most basic one is protecting the plastic crystals from water, because they will disolve. ''We are working on some kind of finishing or encapsulation process,'' the researcher explains.
Another problem, at least for its potential use in clothing, may be weight. The material is not bulky like current insulating material, but the plastic-crystal treatment doubles the weight of the cloth. Also, the lifetime of the material must be determined.
Still, this is just one of a number of novel materials that clothing designers of the future will have to work with, the textile expert says, adding, ''Just as we have seen aproliferation of specialty chemicals designed for very specific purposes, I think we will see the introduction of a growing number of specialty fibers.''