Polyamide fiber strength is high, the strength is 4-5.3 CNdtex, elongation is 18% to 45% elastic recovery rate is above 90% when 10% elongation. Nylon the strongest power in the fiber, according to the determination of polyamide fiber wear-resistant 10 times of cotton fiber, viscose 50 times, abrasion resistance among the top of the various kinds of fiber, so with rubber pressure is ideal material of automobile tires. Polyamide fiber resistance to strong alkali, weak acid, under the 95 ℃ with the Nao (10%) after processing 16 h strength loss is negligible, but nylon does not discolor easily brittle resistance to light, so the nylon fabric is unfavorable and long-term exposure in the sun. But the nylon 66 cannot be used in the pharmaceutical, food manufacturers, because it is poisonous, harmful to human body health.