| 摘要 |
Amorphous fibers or fibrids of poly [4,4'-(2,2'-dicarboxy) biphenyleneterephthalamide] are strengthened and heat stabilized by a relaxed heat-treatment. The fiber or fibrids are heated at temperatures in the range of 310 DEG C. to 365 DEG C. and preferably at temperatures above 325 DEG C. but below decomposition temperatures. The heating is conducted for at least 2 minutes, preferably from 5 to 15 minutes. Increases in tenacity of at least 25%, preferably at least 50% or more are attained. The fiber or fibrids are treated while free of ternsion as they would be in a loose batt, woven or knitted fibric or paper. |
