Cellulose/cellulosic fibers

Cellulose is used in the textile industry in cloths, cartons, carpets, blankets, and sheets. Paper is made from cellulose. Cellulosic fibers are also used as filter materials in artificial kidneys and reverse osmosis though today most kidney dialysis units use cuprammonium tubular films derived from cellulose rather than cellulose itself. 

Pore sizes in cellulose hber are about 10 nm (0.01 pm). Only the smallest HDPE chains, with molecular weight smaller than 10,000 Da, can enter pores of cellulose. Cellulose fiber diameters are typically between 3 and 5 pm. 

Quantacure PDO 65996-61-4 Cellulose Cellulose fibers 65996-62-5 Food starch, modified... 

Cellulose ethyl hydroxyethyl ether. See Ethyl hydroxyethyl cellulose Cellulose fibers CAS 65996-61-4 Synonyms Pulp, cellulose Empirical CeHeOe... 

Rayon. Originally named artificial silk or wood silk, rayon is a transparent fiber made of processed cellulose. Cellulose fibers from wood or cotton are dissolved in alkali to make a solution called viscose, which is then extruded through a spinneret into an acid bath to reconvert the viscose into cellulose. Unlike nylon and polyester, rayon wicks water, so it s ideal for use as a clothing textile. 

There are already encouraging alternatives. Processes with N-methyl morpholine oxide/water as a solvent for cellulose (- cellulose fibers) are now in commercial use. These fibers have been given the generic name Lyocell . Under these circumstances, the importance of regenerated or modified cellulose fibers may increase once again. 

As Figure 25 8 shows the glucose units of cellulose are turned with respect to each other The overall shape of the chain however is close to linear Consequently neigh boring chains can pack together m bundles where networks of hydrogen bonds stabilize the structure and impart strength to cellulose fibers... 

Total airborne particulates are determined using a high-volume air sampler equipped with either cellulose fiber or glass fiber filters. Samples taken from urban environments require approximately 1 h of sampling time, but samples from rural environments require substantially longer times. 

Fig. 8. The resistance of cellulose fibers to biological attack via sod-burial testing.

W. B. Russo and G. A. Serad, in A. L. Turbak, ed.. Solvent Spun Rayon, Modified Cellulose Fibers and Derivatives, ACS Symposium Series 58, American Chemical Society, Washington, D.C., 1977, p. 96. 

Table 1. 1990 World Production of Regenerated Cellulose Fibers...

Again, irrespective of the hardware the chemistry is consistent. The partially regenerated fiber from the spinning machine is contaminated with sulfuric acid, 2inc sulfate, sodium sulfate, carbon disulfide, and the numerous incompletely decomposed by-products of the xanthation reactions. The washing and drying systems must yield a pure cellulose fiber, suitably lubricated for the end use, and dried to a moisture level of around 10%. 

Bulky Rayons. Unlike the thermoplastic synthetic fibers, viscose rayon cannot be bulked by mechanical crimping processes. Crimpers impart crimp to a regenerated cellulose fiber but it is not a permanent crimp and will not survive wetting out. 

The cellulose dissolving potential of the amine oxide family was first realized (79) in 1939, but it was not until 1969 that Eastman Kodak described the use of cycHc mono(/V-methy1amine-/V-oxide) compounds, eg, /V-methylmorpho1ine-/V-oxide [7529-22-8] (NMMO), as a solvent size for strengthening paper (80) by partially dissolving the cellulose fibers. 

The reinforcing ply of laminates may be a woven fabric scrim, a nonwoven web of polymer monofilaments, or a mat of fibers. One of the most common reinforcements in use is also one of the oldest, ordinary cellulose fiber paper. 

The most commonly used reinforcement for high pressure decorative and industrial laminates is paper (qv). The strong substrate layers, or filler, are kraft paper. Kraft is a brown paper made from a sulfate pulp process (8). It consists of both short cellulose fibers from hardwoods and long fibers from conifers. The long fibers impart most of the wet strength required for resin saturation processes. 

Air and Oil Filters. Liquid resole resins are used to coat and penetrate the cellulose fibers of filters and separators in order to increase strength and stiffness and protect against attack by the environment. The type of phenoHc to be used depends on both the final property requirements and the papermaking process. 

Natural Products. Many natural products, eg, sugars, starches, and cellulose, contain hydroxyl groups that react with propylene oxide. Base-cataly2ed reactions yield propylene glycol monoethers and poly(propylene glycol) ethers (61—64). Reaction with fatty acids results ia a mixture of mono- and diesters (65). Cellulose fibers, eg, cotton (qv), have been treated with propylene oxide (66—68). 

Both mechanical and chemical action promote ink detachment from cellulose fibers during pulping. Mechanical action includes interfiber abrasion and fiber flexing and bending. Chemical action includes fiber swelling and surfactant-promoted ink particle emulsification and solubilization. 

Ink particle redeposition on cellulose fibers can reduce deinked paper brightness. Should larger ink particles redeposit on fibers, visible ink specks may result. Sodium siUcate is often added to the pulper to act as a dispersant and reduce this redeposition (6,14). Up to 5% based on dry paper weight may... 

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