Fibre conversion process

How the starting material is converted into the fibre product can be hard for those lacking a scientific background to understand. The following graphics provide a simplified visual explanation of the process from the starting material to the creation of usable fibres for seven of the most frequently encountered semi-synthetic and synthetic fibres. They are presented in the order in which the fibres were invented to provide a sense of how the processes developed and were refined.

 

Viscose Rayon

A diagram showing wood pulp being treated with caustic soda, mixed with carbon disulphide, dissolved in caustic soda, and the extruded into a bath of sulphuric acid.

 

Acetate Rayon

A diagram showing wood or cotton pulp being dissolved in acetic anhydride and sulphuric acid, then washed in water to remove the acid, then dissolved in acetone, and extruded to create the filament.

 

Casein fibre

A diagram showing waste milk being skimmed to remove the fat, the dewatered and purified to obtain casein fibre, this is dissolved in alkali solution, this is passed through a spinneret to create filaments, the filaments are immersed in dilute sulphuric acid, then treated with formaldehyde and aluminium salts.

 

Nylon

A diagram showing adipc acid and hexamethylenediamine from petroleum being mixed with water to create nylon salt.  This then goes through polymerisation, the resulting polyamide is heated to a liquid and then extruded to create a filament.

 

Acrylic

A diagram showing propylene from petroleum mixed with ammonia to create acrylonitrile.  This then goes through the process of polymerisation and then dissolved in solvent.  It is filtered and then extruded into acrylic filament.

 

Polyester

A diagram showing terephthalic acid and ethylene glycol from petroleum are mixed and go through the polymerisation process.  The resulting polyester is heated to a liquid and extruded to create polyester filament.

 

Lyocell

A diagram showing wood pulp dissolved in a non-toxic organic solvent, the solution is extruded to create filament which is washed, finished and dried.  The effluent from washing is processed and recycled.

 

Polylactide

A diagram showing starch extracted from raw materials (such as corn or sugarcane) being put through enzymatic hydrolysis to produce glucose, it is fermented to produce lactic acid, then distilled to product lactide, it goes through polymerisation and turned into PLA chips.  These are heated to a liquid and then extruded to create PLA filament.