Cellulose types

The mechanical properties of natural fibers depend on cellulose type because each type of cellulose has a specific cell geometry and the geometrical conditions determine the mechanical properties. 

Cellulosic They are tough, transparent, hard or flexible natural polymers made from plant cellulose feedstock. With exposure to light, heat, weather and aging, they tend to dry out, deform, embrittle and lose gloss. Molding applications include tool handles, control knobs, eyeglass frames. Extrusion uses include blister packaging, toys, holiday decorations, etc. Cellulosic types, each with their specialty properties, include cellulose acetates (CAs), cellulose acetate butyrates (CABs), cellulose nitrates (CNs), cellulose propionate (CAPs), and ethyl celluloses (EC). 

Fig. 9. — Antiparallel packing arrangement of the 3-fold helices of (1— 4)-(3-D-xylan (7). (a) Stereo view of two unit cells roughly normal to the helix axis and along the short diagonal of the ab-plane. The two helices, distinguished by filled and open bonds, are connected via water (crossed circles) bridges. Cellulose type 3-0H-0-5 hydrogen bonds stabilize each helix, (b) A view of the unit cell projected along the r-axis highlights that the closeness of the water molecules to the helix axis enables them to link adjacent helices.

In the case of aerated protein icings, however, stabilizers are essential. Where hot water is used, gelling-type stabilizers work best (agar, gelatin, Irish moss extract). In cold foams, prepared with cold water, cellulose-type gums are used to contain water in the foams colloidal precipitates, such as are formed through the reaction of carrageenin and protein, are very helpful. 

Ichihara, H., Fukushima, T., Imai, K. (1999).. Enantiomeric determination of d- and L-lactate in rat serum using high-performance liquid chromatography with a cellulose-type chiral stationary phase and fluorescence detection. Anal. Biochem. 269, 379-385. 

This term was originally intended to denote all kinds of man-made textile fibres, but is now applied only to cellulose types. Viscose rayon (regenerated from a solution of cellulose xanthate in sodium hydroxide) accounts for the greater part of world rayon production. Acetate rayon and cuprammonium rayon are relatively unimportant. 

Measurements of particle porosity are a valuable supplement to studies of specific surface area, and such data are particularly useful in the evaluation of materials used in direct compression processes. For example, both micromeritic properties were measured for several different types of cellulosic-type excipients [53]. Surface areas by the B.E.T. method were used to evaluate all types of pore structures, while the method of mercury intrusion porosimetry used could not detect pores smaller than 10 nm. The data permitted a ready differentiation between the intraparticle pore structure of microcrystalline and agglomerated cellulose powders. 

LMC is used in underwater concrete for both new construction and repair. The important requirements to obtain antiwashout capability, such as segregation resistance, flowability, self-leveling characteristics and lower bleeding are provided by the addition of viscosity-enhancing polymeric admixtures at polymer-cement ratios of 0.2-2.0%. These admixtures are water-soluble polymers, and classified under two groups, viz., cellulose types such as methyl cellulose and hydroxy ethyl cellulose and polyacrylamide types such as polyacrylamide and polyacrylamide-sodium acrylate [101]. 

It has been shown that keratin [9008-18-8], and not cellulose-type fibers, are dyed. It is speculated that a lead—sulfur—keratin complex is formed. The color penetrates the hair fiber to a limited extent, forming a ring around the outside edge and imparting a lifeless appearance. Once developed, the color cannot be removed. The shades are limited yellows or light browns. Appealing mainly to men, the products are often called color restorers because of the... 

T. Uryu, J. Yamanouchi, T. Kato, S. Higuchi, and K. Matsuzaki, Selective ring-opening polymerization of di-O-methylated and di-O-benzylated 1,4-anhydro-u-D-ribopyranoses and structure proof of synthetic cellulose-type polysaccharide (1 - 4)-/i-D-ribopyranan and (1 - 5)-u-D-ribofuranan, J. Am. Chem. Soc., 105 (1983) 6865-6871. 

M. Ogawa, K. Hatanaka, and T. Uryu, Synthesis of a novel cellulose-type hexopyranan 6-deoxy-(l - 4)-u-L-talopyranan by selective ring-opening polymerization of 1,4-anhydro sugar derivatives, Macromolecules, 24 (1991) 987-992. 

T. Yoshida, L. X. Song, C. P. Wu, K. Hatanaka, and T. Uryu, Selective synthesis of cellulose-type copolymers by ring-opening copolymerization of 1,4-anhydro-a-D-ribo-pyranose derivatives, Chem. Lett., (1991) 477-480. 

MEM Methocel minimum essential medium carboxymethyl cellulose type MC (4000 centripoi-ses) sold by Dow Chemical Co. 

Center at Valley Forge, Pa. (9). It was the Library of Congress recommendation for the safety limits of cellulose-type materials which made possible the success of this project and others which have followed. After the St. Louis fire at the Military Records Center, the Library of Congress was again involved in vacuum—air purge drying operations, this time in collaboration with McDonnell Douglas Aircraft Corp. (7). 

Polymer Adsorption Several reviews on the subject of polsmier adsorption are presented by Eirich and coauthors [60,61] and Kipling [62]. The adsorption of polymers that have been considered include synthetic rubber, cellulose-type poisoners, methacrylate, styrene, vinyl pol3miers. Most studies have been performed in polar organic solvents, primarily on carbon as a solid, no doubt because of the bias of the rubber industry. Another important point is that the polymers ts ically used are of a wide molecular weight distribution and their adsorption... 

Matusiewicz, H. Review of sample preparation methodology for elemental analysis of cellulose type materials. ICP Inf. Newsl. 25, 510-514 (1999)... 

Pitch type ACF PAN type ACF Phenol type ACF Cellulose type ACF... 

The Y axis in the figure indicates the SO2 breakthrough ratio (outlet SO2 concentration / inlet SO2 concentration). The figure shows the de-SOx activities of these 4 kinds of ACFs in decreasing order pitch-type, PAN-type, phenol type, and cellulose-type ACFs. The figure also revealed that the de-SOx ratio was kept stable even after 1S hours. 

In another study, thermodynamic parameters have been investigated with a tris(4-methyIbenzoate)-derivatized cellulose type CSP (Chiralcel OJ) and a chiral diol compound. It was found that at low temperatures, the enantioselectivity is entropy-driven (region 11), while at higher temperatures the separation is enthalpy-driven (region 1) (see Fig. 9.8). DSC and IR experiments revealed that the transitions between the enthalpic and the entropic regions of the van t Hoff plots are a result of a change in conformation of the stationary phase [76]. 

Doelker, E. Comparative compaction properties of various microcrystalline cellulose types and generic products. Drug Dev. Ind. Pharm. 1993,19 (17, 18), 2399-2471. 

Excipient Low-substituted hydroxypropyl cellulose, type LH-11 Manufacturer Shin-Etsu Magnification 350x... 

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