Tuesday, 17 May 2011

What Are Regenerated Fibres?

Regenerated fibres are fibres that are from natural cellulose sources but require chemical modification in order to be compressed into their fibre form.Tencel (Lyocell) is a regenerated fibre and is made out of eucalyptus trees. In order to transform the tree into a fibre the process of which it undergoes is called solvent spinning, the trees are chopped up into chips and then chemically broken down in a bath until it is made into a pulp. This pulp is then pushed through a spinneret to form individual fibres, later the Lycocell fibres are washed of all chemicals used and the chemicals are then retrieved from the water. This process is environmentally sound as the chemicals, when retrieved from the water, are purified and recycled, the only products are clean water and Lyocell fibres.

Another regenerated fibre is Viscose which is made from bamboo. Similar to Lyocell, the bamboo is allowed to 'steep' meaning that it is emmersed into Sodium Hydroxide in order to swell the cellulose fibres, next the swollen Alkali cellulose mass is pressed into a wet block. Next the pressed blocks are shredded to create finely divided and fluffy particles which are known as 'crumbs' and then the alkali cellulose is allowed to age (under controlled conditions) in order to depolymerize the cellulose. Later comes Xanthantion which is when the crumbs are placed in a vat and are allowed to react to carbon disulphide, after this the crumbs are dissolved in Caustic Soda. Then the Viscose is allowed to stand for a period of time in order to 'ripen', after this the Viscose is filtered to remove any undissolved materials that could disturb the spinning. It is then degassed where air bubbles are removed so that do not cause week spots in the viscose. Viscose is then Wet Spun, where the production of the Rayon filament happens, the solution is passed through a spinneret and into a bath of Sodium Solphate and this solidifies the solution. The filaments are then drawen out and stretched whilst still being slightly mobile, this causes the chain to orient along the fibre axis. Finally, the Rayon/Viscose is washed of all salts and cut into staple fibres.
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