Cellulose acetyl

The predominant cellulose ester fiber is cellulose acetate, a partially acetylated cellulose, also called acetate or secondary acetate. It is widely used in textiles because of its attractive economics, bright color, styling versatiUty, and other favorable aesthetic properties. However, its largest commercial appHcation is as the fibrous material in cigarette filters, where its smoke removal properties and contribution to taste make it the standard for the cigarette industry. Cellulose triacetate fiber, also known as primary cellulose acetate, is an almost completely acetylated cellulose. Although it has fiber properties that are different, and in many ways better than cellulose acetate, it is of lower commercial significance primarily because of environmental considerations in fiber preparation. 

In one process to produce highly activated cellulose for acetylation, cellulose is treated with NaOH (mercerization) followed by a hydroxyalkylating agent, eg, ethylene oxide or propylene oxide, to give a cellulose hydroxyalkyl ether with a DS of 0.05—0.3 (76). The resulting water-insoluble material is highly reactive to conventional acetic anhydride—sulfuric acid acetylation. 

The methods available today may be considered under two headings, homogeneous acetylation, in which the acetylated cellulose dissolves into a solvent as it is formed, and the heterogeneous technique, in which the fibre structure is retained. 

The potential for use of chiral natural materials such as cellulose for separation of enantiomers has long been recognized, but development of efficient materials occurred relatively recently. Several acylated derivatives of cellulose are effective chiral stationary phases. Benzoate esters and aryl carbamates are particularly useful. These materials are commercially available on a silica support and imder the trademark Chiralcel. Figure 2.4 shows the resolution of y-phenyl-y-butyrolactone with the use of acetylated cellulose as the adsorbent material. 

To develop a continuous process, the immobilisation of aminoacylase of Aspergillus oryzae by a variety of methods was studied, for example ionic binding to DEAE-Sephadex, covalent binding to iodo-acetyl cellulose and entrapment in polyacrylamide gel. Ionic binding to DEAE-Sephadex was chosen because the method of preparation was easy, activity was high and stable, and regeneration was possible. 

Penta-erythritol Diacetate Dipropionate", ERDE 11/M/58 (Oct 1958), AD 206266 (DDCSTI users only) 6) V. Pasquale, Feasibility Study on Using Low Acetyl Cellulose Acetate Inhibitor for Production Cast Grains , NOSIH TR 317 (10 July 1970), AD 510578 (Conf) 7) CPIA Solid Propellant Manual , CPIA/M2 (28 Jan 1974), unit 1069 (Conf)... 

The primary OH group can be selectively blocked by the bulky triphenyl-methyl (trityl) moiety, followed by esterification at the secondary OH groups and removal of the protecting trityl group. Thus 2,3-di-O-acetyl cellulose has been obtained by this procedure. Moreover, regioselectively substituted mixed cellulose esters, acetate/propionate, were prepared by subsequent acy-... 

The interaction between polymer matrix and filler leads to the formation of a bound polymer in close proximity to the reinforcing filler, which restricts the solvent uptake [13]. The composites containing acetylated cellulose fillers exhibited higher uptake of toluene compared to water in accordance with their hydrophobic nature. 

A new Ni(II) optical chemical sensor based on immobilizing of 2-amino-lcyclopentene-ldithiocarboxylic acid (ACDA) (Figure 21), to transparent acetyl cellulose films was developed52. 

In 1894, Cross and Bevan acetylated cellulose to get cellulose acetate. In 1921, cellulose acetate fibres were marketed for the first time as Celanese. ... 

Cellulose and Acetylated Cellulose These adsorbents are commercially available in various forms e.g., particle size, degree of acetylation, with or without binders like starch or Plaster of Paris. 

BP Chemicals developed a pilot-scale plant for the acetylation of wood fibres in collaboration with A-Cell acetyl cellulosics AB, Depac Engineering and the BioComposites... 

On the basis of the development work undertaken by BP Chemicals in Hull and research performed at Chalmers University in Gotenborg, Sweden, and the USDA Forest Products Laboratory in Madison, Wisconsin, USA, a fibre acetylation pilot plant was commissioned in 2000 at Kvarntorp in Sweden. The plant has a capacity of 4000 tonnes of acetylated fibre per year (Simonson and Rowell, 2000). The process and plant are jointly owned by A-Cell Acetyl Cellulosics AB and GEA Evaporation Technology AB. A schematic of this process is shown in Eigure 8.5. 

Loeb,S., "Characteristics of Porous Acetyl Cellulose Membranes for Pressure Desalination of Dilute Sodium Chloride Solutions, Master of Science Thesis,UCLA Dent, of Engineering,May,1959. 

Acetate fiber is the generic name of a fiber that is partially acetylated cellulose. They are also known as cellulose acetate and triacetate fibers. They are nontoxic and generally non-allergic, and so are ideal from this aspect as clothing material. 

Partially acetylated cellulose (i.e., cellulose with less than three ester groups per repeat unit) is produced by an indirect route. Direct synthesis yields an inhomogeneous product due to insolubility of cellulose in the reaction mixture. Some chains are completely acetylated while others may be completely unreacted. A partially acetylated product is usually produced by controlled hydrolysis of the triacetate. The triacetate is soluble in the reaction mixture and complete solubility ensures that the final product will be more homogeneous. Hydrolysis of the triacetate is carried out by controlled reversal of the esterification reaction by the addition of water or dilute acetic acid. 

B.I. Shekhter has shown that, if in deton the chges are placed in an acetyl-cellulose tube with walls 0.15 mm thick, the maximum distance increased by 40-50% (Ref 23, p 766) In the section on detonation by influence in condensed media (Ref 23, pp 771-78), it is reported that E. Burlot conducted in France experiments with 50 g charges of PA (Melinite) loaded at density 1.25 in cardboard cartridges of 28 mm diam. When donor and receptor were separated by air, the distance at 50% explns was 28 cm, whereas for water it was only 4 cm for clay 2.5, sand 1.5, fir tree 3.5 to 4 and steel 1.5 cm Shekhter et al detd in Russia (Ref 23, pp 774-78) deton thru various media from a 35.5 chge of phlegmatized (with.6% wax)... 

Cellulose acetate fibers are defined by the Textile Fiber Products Identification Act as manufactured fibers in which the fiber-forming substance is cellulose acetate in which not less than 92% of the hydroxyl groups are acetylated. Cellulose triacetate is employed to make many tricot fabrics and sportswear. Cellulose triacetate textile is shrink- and wrinkle-resistant and easily washed. 

Acetyl Celluloses (AC) (Acetates of Cellulose or Cellulose Acetates). According to Doree(Ref 3) the action of AcaO on cellulose (called acetylation) should theoretically yield the triacetate [CfiH702(00C. CH3)s]n. Actually, the products of acetylation are a mixture of tri-, di- and mono-acetate. A characteristic property of the lower acetyl-ated acetates is their sol in acetone, whereas the triacetate can absorb acetone only to the extent of causing swelling... 

The influence of the polarity of solvents on their ability to dissolve nitrocellulose has been also demonstrated by Wo. Ostwald [50], who has introduced the value fi2/e as an expression characterizing the strength of solvent ( —dipole moment, e-dielectric constant). Good solvents of acetyl celluloses are characterized by a high iM2/s value. The physical significance of /i2/e is not clear, however, and its introduction has not helped to clarify the process of dissolution. 

Wrasidlo 79) fabricated semipermeable poly(N-amide)imide (26) membrane from 3,3, 4,4 -benzophenonetetracarboxylic dianhydride (27) and isophthalic dihydrazide (28). The membrane with 28 i thickness had a water flux of 11401/m2 day-2000 A and salt rejection of 99.95%, while a 39.8% acetylated cellulose acetate membrane with 16 ji thickness had values of 118 1/m2 day and 99.35%. 

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