The appearance of PA is transparent or opaque milky white or pale yellow granules, with a hard, keratinous surface and a glossy finish. PA has a high water absorption rate, which increases with the proportion of amide groups. PA is a self-extinguishing plastic, emitting a burnt wool or nail smell when burning. PA is a moderately barrier plastic; its barrier properties improve with an increased ratio of amide to methylene groups, with PA6 offering the best barrier effect.Widely used in industrial production for manufacturing bearings, circular gears, cams, bevel gears, various rollers, pulleys, pump impellers, fan blades, worm gears, propellers, screws, nuts, washers, high-pressure seals, oil-resistant sealing gaskets, oil-resistant containers, casings, hoses, cable sheaths, shear machine wheel sleeves, planer slides, electromagnetic distribution valve seats, cold storage equipment, pads, bearing retainers, various fuel lines, pistons, ropes, drive belts on cars and tractors, textile machinery industrial equipment accessories, as well as daily necessities and packaging films, etc.