What kind of fibers the same question? In the first all – of the heat-resistant, able to work for a long time at high or very high temperatures. Then – about hemostoykih that can withstand prolonged contact with the most aggressive chemical environments: strong acids, alkalis and oxidizing agents. And finally, the question is, apparently, of the fibers used in one of the most important areas such as medicine, particularly in surgery and alloplastica. Technique every day increases the demands on heat resistance, heat resistance materials. Two or three years ago, we were not aware of fibers and fabrics, can hundreds of hours working at a temperature of 250-300 , without compromising the strength or failure. And now required for fiber work in more severe conditions – at temperatures above a thousand degrees.
And these synthetic fibers have already been established. True, the "work" as long as they only a few minutes. But the thing that has identified ways to address this complex and very important technical problem. The search for chemists working in this field are focused generally on certain classes of synthetic polymers, especially hetero. Macromolecules of the substances containing aromatic ring, different stiffness – it makes heat-resistant polymer.
On the basis of precisely such polymers, American scientists have created two years ago, polyamide fiber-HT, the temperature "endurance" of which reaches 350-450 C. There are methods for producing fibers capable of withstanding a short time heating to 700-1000 . These macromolecules also have a cyclic structure. But this structure is not characteristic of the source material, it occurs in the fiber at a special treatment. What does this mean? Take, for example, normal poliakrilnitrilnoe fiber. It shrinks and loses its strength even at 150-180 . But start to warm up the fiber, slowly raising the temperature to 250-300 -and structure, and with it the properties of the fiber gradually changed.