Cellulose, wetting

Evidence was presented that thallous ethylate did not penetrate or alter the crystalline parts of the fiber. Moreover, it was possible to conduct the thallation with different solvents for thallous ethylate. When this was done with normal ethers, the extent of methylation was observed to decrease as the molecular volume of the thallous ethylate solvent increased. These results suggested that accessibility is dependent upon the penetrating power of the ether solvent. Amorphous cellulose was, therefore, defined as the percentage of cellulose wetted by an ether of zero molecular volume and was estimated by determining methylation-molecular volume values for three or more straight-chain ethers, plotting the data and extrapolating to obtain methoxyl content for an ether of zero molecular volume. The amount of cellulose corre-... 

A process of obtaining a cellulosic wet sheet and a membrane and equipment for their manufacture Development of high performance leukocyte reduction filters based on ultra-fine non-woven fabric Development of a novel adsorbent based on bacterial cellulose for adsorption of rare earth metals Metallization of bacterial cellulose for electrical and electronic device manufacture... 

Later the same research group claimed that, in the first step of the in situ synthesis scheme, ionic functional groups as such are not necessary for the introduction of ferrous ions into a cellulose matrix [161,162], This suggestion was made based on a comparative study of ferrite synthesis between a case with anionically modified cellulose materials and the other case with non-ionic cellulose gels, which included a never-dried bacterial cellulose (BC) membrane and a never-dried cellulose wet-spun filament or cast film (Lyocell) using N-methylmorpholin-N-oxide as the solvent. SPM proper-... 

Luukkonen P, Schaefer T. Hellen L. et al. Rheological characterization of microcrystalline cellulose and silicified microcrystalline cellulose wet masses using a mixer torque rheometer. Im J Pharm 1999 188 181-92. 

NITROCELLULOSE or NITROCELLULOSE E950 or nitro-cellulose, wetted, plasticized, soiution or NITROCELLULOSE, wet with >= 30% aicohoi or SOLVENT NITROCELLULOSE avec au moins 25% d aicooi (French) or NITROCELLULOSE avec de i alcooi (French) or NITROCELLULOSE, humidifiee, avec au minimum 30% D ALCOOL OU SOLVANT (French) or NITROCELLULOSE, wet, with not less than 30% alcohol or solvent or NITROCELLULOSE with not less than 25% alcohol or NITROCELULOSA, CON ALCOHOL (Spanish) or... 

The results presented here refer specifically to membranes synthesized by Bionext s strain. Bionext is a Brazilian company that produces bacterial cellulose for medical applications. At this company, bactaial cellulose wet membranes are dried by compression and heating, a process that confers unique texture charactaistics. 

Uematsu T, Matsui Y, Kakiuchi S, Isogai A (2011) Cellulose wet wiper sheets prepared with cationic polymer and carboxymethyl cellulose using a papermaking technique. Cellulose 18 1129... 

Figure 2.2 Photographs of a static culture (with a visible BC pellicle in the interface air-culture medium) and a purified bacterial cellulose wet membrane produced in static conditions. Reproduced with permission from [29, 39].

Cellulose wet spinning rayon polymer is derivatized during dissolution in NaOH lyocell direct dissolution in NMMO... 

Processed natural fibre cellulose Wet-laid (paper, filter sheets)... 

Fig. 2. Cellulose acetate stress—strain properties at standard and wet conditions, tested at 60% min extension rate, 3.9 cm gauge length. Sample conditions standard, 21°C, 65% rh wet, 21°C, water wet. To convert N/tex to gf/den, multiply by 11.33.

The precipitated cellulose acetate is filtered from the dilute (25—36%) acetic acid. The acetic acid and salts remaining from the sulfuric acid neutrali2ation are removed by washing. The wet polymer is typically dried to a moisture content of 1—5%. The dilute acetic acid obtained from the washing and precipitation steps caimot be used in other stages of the process. Its efficient recovery and recycle are an economic necessity. 

Carbon disulfide [75-15-0] is a clear colorless liquid that boils at 46°C, and should ideally be free of hydrogen sulfide and carbonyl sulfide. The reaction with alkaU cellulose is carried out either in a few large cylindrical vessels known as wet chums, or in many smaller hexagonal vessels known as dry chums. In the fully continuous viscose process, a Continuous Belt Xanthator, first developed by Du Pont, is used (15). 

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. 

Fig. 8. (a) Cross section of cellulose acetate isotropic porous hoUow-fiber dry-jet wet spun at incipient gelation point of dope mixture (b) magnification at... 

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. 

The recovery of fiber from broke (off-specification paper or trim produced in the paper mill) is compHcated by high levels of urea—formaldehyde and melamine—formaldehyde wet-strength resin. The urea resins present a lesser problem than the melamine resins because they cure slower and are not as resistant to hydrolysis. Broke from either resin treatment may be reclaimed by hot acidic repulping. Even the melamine resin is hydrolyzed rapidly under acidic conditions at high temperature. The cellulose is far more resistant and is not harmed if the acid is neutralized as soon as repulping is complete. 

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