Viscose rayon mixing

However, there are potential risks associated with using bamboo as a polymer source for rayon since there is currently a lack of transparency in the supply chain. It is not always clear which type of bamboo is used for fibre, where it is grown, how it is cultivated, how it is harvested, and so forth. To date, there is no known organic certification of bamboo. The process to make bamboo viscose rayon fibre is the same process that is used to produce viscose/rayon from any other plant source. The cellulose is extracted from the bamboo and then mixed with chemicals to convert the plant pulp into textile quality fibre. This process can be very polluting unless it is carefully controlled, and can be influenced by the age and condition of the equipment as well as by whether there is any by-product recycling or effluent treatment. Note that in most countries the fibre cannot be called bamboo, only rayon or viscose from bamboo (textileexchange.org). 

Wood pulp is the principal raw material of the lyocell process in terms of cost and volume. The grade used is similar to the dissolving pulp used for viscose rayon but has a slightly lower degree of polymerisation (DP) Tencel fibres have a DP of 500 to 550. The pulp is pulled from the reels into a shredder, which cuts the pulp into small pieces for mixing with the amine oxide solvent. The amount of pulp fed to the mixer has to be accurately measured so that the cellulose content in solution is closely controlled. 

Cuprammonium rayon is made from scoured and bleached cotton linters or purified wood pulp with a high a cellulose content. The cellulose is washed and then pressed until it contains about 50 per cent of water. In this state, it is placed in a mechanical mixer together with cuprammonium solution and agitated until completely dissolved, whilst the temperature is maintained at 5° C (41 °F). The solution is then diluted to about 10 per cent concentration. After filtration and exposure to vacuum to remove air bubbles and dissolved gases, the solution is allowed to ripen in enclosed vessels until it is the desired viscosity. In modem practice copper carbonate is mixed intimately with the cellulose in a shredding machine and the resultant mass is then broken up and stirred for some hours with aqueous ammonia and caustic soda, when it passes into solution. 

Regenerated cellulose n. A transparent cel-lulosic plastic made by mixing cellulose expatiate with a dilute sodium hydroxide solution to form a viscose extruding the viscose into film, sheeting, or fiber form, then treating the extrudate with acid to effect regeneration. In fiber form, the material is called rayon. The term cellophane is used for films and sheets. 

Artificial fibres are as much in common use as the plastics and have equally interesting histories, as documented in Jenkins (2003). One of the first artificial fibres was rayon, the starting point for which is cellulose from wood pulp. It was first discovered in 1855 and was commercially produced by 1924 in the USA. Rayon is produced in two stages. First, cellulose is mixed with sodium hydroxide and carbon disulphide to produce viscose which, as its name suggests, is a thick, sticky liquid. As in the case of Terylene, the viscose is then forced through fine holes in a cylinder (a spinneret) as a jet and into dilute sulphuric acid to produce rayon. This is a fine, almost silky thread with multiple uses which include textiles, tyres and carpets. 

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