fibres and yarns, man-made

All man-made fibres are made from polymers.
Most of these polymers are chemically produced and the resulting fibres are completly man-made.
These fibres are defined as synthetic.

Others are natural vegetable (cellulosic) polymers
that have been interfered with and altered by man.
The fibres resulting from these polymers sit in one of two sub-groups known as regenerated or modified.

In order to make them into filaments all polymers must be converted to a liquid form.

The molten polymer can then be extruded (forced through fine holes) to form long continuous threads or filaments.
The molten filaments then have to be solidified, usually by being passed through a cooling air current.

After extrusion the plastic (solid, but still pliable) filament is drawn or stretched over rollers.
This process is needed to align the molecules along the length of the fibre axis.

Some of these filaments remain as continuous lengths of filament.

Others are chopped into staple lengths ready to be spun into staple yarns.
The chopped staple can either to be blended with other fibres or spun on it's own.

Three different methods are used for extruding the fibres.
The method chosen depends on the ease with which the polymer can be turned into a liquid.

melt extrusion
Used for a polymer which when heated will melt and become liquid.
The viscous solution is extruded and coagulates on cooling.
Some common brand names include: Nylon, Polyester, Polypropylene.

solvent-dry extrusion
Used for a polymer that would be damaged by heating,
but is able to be dissolved in a volatile solvent that evaporates.
The molten filament is extruded into warm air; the solvent evaporates, and the filament solidifies.
Some common brand names include: Orlon, Dralon and some Acrylics.

solvent-wet extrusion
Used for a polymer that would be damaged by heating,
and can only be dissolved in a non-volatile solvent that does not evaporate.
In order to solidify the viscous solution has to be extruded into a chemical coagulating bath.
Some common brand names include: Courtelle, Acrylan.

MAN-MADE FIBRES

AN OVERVIEW