Depending on its chemical state, nylon can have very different physical properties, so that it seems as if materials of completely different kinds are involved. It is a well-known fact that nylon is used primarily in the textile industry and rope production, because it is elastic and resistant, does not require ironing and is not attacked by moths. In addition to this fibrous form, nylon is available in a rigid form too, however. Its outstanding characteristics here: exceptional hardness and toughness, abrasion resistance (articles that are subject to friction need no lubricants), resistance to wear, heat, chemicals and solvents as well as an ability to absorb impact, noise and vibration. Its tensile and flexural strength (400-600 kg/cm²) is comparable to metals. It is no surprise that the engineering sciences have discovered nylon for their purposes too: in its rigid configuration, nylon is used to manufacture such products as wheels (including gearwheels), gear bearings, screws, wall plugs, parts for household appliances and tools. In its fibrous or flexible configuration, it is used not only for textiles but also for such products as ropes, cables, fishing lines, fishing nets, fibres for carpets and airbags, parachutes, sails, guitar strings, tennis racket strings, medical stitching material and – last but not least – bristles for toothbrushes.