Synthetic fibers have some properties superior to those natural including: high strength, excellent chemical resistance, resistance to moth and decay. Synthetic fibers can give them properties which they do not have those natural: non flammability, resistance to high temperatures, etc.. There are some unsatisfactory properties: low moisture absorption, high electrostatic charge, pilling effects, color more difficult. With the appearance of new types of synthetic fibers, to spinning processes known they have been added new ones: the melt spinning and, more recently, spinning the suspension, the semi melt spinning, etc..
In general, the scheme for obtaining a synthetic fiber is:
preparation of polymer -> spinning -> yarn drawing ->wrinkling -> fixing.
The last time, is widely used and spinning co. Co spun fibers have two structures: "shell-core" and "side by side " Skin-core fibers have a core of a polymer fiber that gives strength, elasticity, etc.., and a shell of another polymer for the lower static loading, increase gloss, reduce pilling etc.
Structure side by side may, for example, to give a large wrinklingto fiber if the two polymers have different contractions. Nylon:
These fibers are used for obtaining molded articles, textiles and medical sutures. Nylon fibers are resilient and more resistant than silk and relatively insensitive to moisture and mildew.
Nylon is a polyamide obtained from petroleum. Nylon is melting and then burns rapidly if the flame remains on fused fiber. If you can keep the flame on burning nylon,it feels a burning plastic smell.