Dry spinning, wet spinning and gel spinning.

Dry spinning.

In dry spinning the polymer is dissolved in its solvent and then extruded, as the fibre emerge from the spinneret the solvent is evaporated off by hot air.
The solvent in most cases is collected and reused.
The polymer used in this method are acetate, triacetate, acrylics, modacrylics, spandex, Vinyon and PBI.
The process is illustrated in fig below.

Mechanism of dry spinning.

Wet spinning.

This is the oldest method.
This type of spinning is required by a polymer which require dissolving in a solvent to be spun.
This method is named wet spinning because the polymer is extruded directly into the liquid bath.
Since the polymer is extruded directly into the liquid, the filament experience a greater drag force than that of polymer extruded in air, due to which speed of this process is reduced as compare to the melt and dry spinning.
This process is based on precipitation.
The polymer fibre spun using this method include acrylics, spandex, aramid and rayon.
This process is illustrated from figure below.

Mechanism of wet spinning.

Gel spinning.

This is a special process used for obtaining high tensile strength and special property polymers.
This process is also known as dry- wet spinning,as the filament is first pass through air and then cooled in a liquid bath.
The gel spinning method is used for obtaining some high tensile strength polyethylene and aramid fibres.
This process is illustrated from figure below.

Mechanism of gel spinning.

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