Cellulose reactivity

In summary, although clear, light-colored cellulose solutions are required to start the synthesis, there is no guarantee, a priori, that the targeted DS will be obtained. The reasons are that the state of aggregation of cellulose is dependent on the structural characteristics of the starting material, is sensitive to the pre-treatment employed, and the impurities present. This may result in non-reproducible aggregation states, and may lead to oscillation in cellulose reactivity. Typically, effects of these oscillations may not be readily apparent, because ... 

Imaginative use has been made of triazine and sulphatoethylsulphone reactive dye chemistry in the application of pretreatments to nylon [405]. The concept resembles that used to make cotton cellulose reactive before dyeing with aminoalkylated dyes, as discussed earlier (Schemes 10.67 and 10.68). In this case, nylon becomes the reactive partner by pretreatment with a reactive multifunctional crosslinking agent ... 

Baxter, A. G. W. Bostock, S. Greenwood, D. (ICI). Water-Soluble Phthalocyanine Black Dyes from Cellulose Reactive Groups and Suitable for Use in Inks. U.S. Patent 4,705,528, November 10,1987. 

The introduction of Calcobond dyes a few years later by American Cyanamid exploited a similar principle but incorporated the N-methylol groups into the dye molecule itself [132]. The labile chloro substituents in dichlorotriazine dyes were converted to amino groups by substitution with ammonia and the resulting melamine residue made cellulose-reactive again by reaction with formaldehyde (Scheme 7.59). A typical member of this range was Cl Reactive Red 92 (7.120). A characteristic problem of the Procion Resin process and of the... 

Cabiaca A, Guillona E, Chambonb F, Knel C, Rataboulb F, Essayem N. Cellulose reactivity and glycosidic bond cleavage in aqueous phase by catalytic and non catalytic transformations. Appl Catal A Gen 2011 402 1-10. 

To evaluate the cellulose reactivity with respect to the esterification reactions, the amount of chemically bound phosphorus in impregnated materials was determined and related to the amount of acid and pretreatment temperature. Two celluloses with a... 

The cellulose acetate manufacturer receives the cellulose in rolls or bales. For wood pulp, the bales consist of sheets of pulp. However, for cotton linters the bales can consist of sheets or cellulose in bulk form. The most important chemical properties are cellulose purity, intrinsic viscosity (IV), and cellulose reactivity. The most important physical properties are sheet density and moisture content. 

Etherification. The accessible, available hydroxyl groups on the 2, 3, and 6 positions of the anhydroglucose residue are quite reactive (96) and provide sites for much of the current modification of cotton cellulose to impart special or value-added properties. The two most common classes into which modifications fall, include etherification and esterification of the cotton cellulose hydroxyls as well as addition reactions with certain unsaturated compounds to produce cellulose ethers (see Cellulose Ethers). One large class of cellulose-reactive dyestuffs in commercial use attaches to the cellulose through an alkali-catalyzed etherification by nucleophilic attack of the chlorotriazine moiety of the dyestuff ... 

The effect of epichlorohydrin- or formaldehyde-crosslinking on the fine structure of cellulose has been investigated. Crosslinking was shown to increase the number of accessible hydroxy-groups, thus improving cellulose reactivity in some esterification reactions. 

Stamberg, J., and Peska, J. 1983, Preparation of porous spherical cellulose, Reactive Polymers, 1 145. 

KUB 98] Kubota H., Shiobara N., Photografting of N-isopropylacrylamide on cellulose and temperature-responsive character of the resulting grafted celluloses , Reactive and Functional Polymers, vol. 37, pp. 219-224, 1998. 

In the same context, a critical review discusses the recent advances in graft polymerization techniques involving cellulose and its derivatives [137]. The study summarizes some of the features of cellulose structure and cellulose reactivity and describes the various techniques for grafting synthetic polymers from the cellulosic substrate. In addition to the traditional grafting techniques, the recent developments in polymer synthesis that allow increased control over the grafting process and permit the production of functional celluloses with improved physical and chemical properties, are highlighted. 

Retention aids are necessary to coagulate and flocculate the pulp and to avoid losses due to fibers, fillers and additives passing through the mesh of the forming screen. ->Cationic starches are the only RR-based polymers used to retain mineral fillers and cellulose-reactive sizes. The market is dominated by polyacrylamide, which is applied as W/O emulsion. The aqueous polymer solution is dispersed in kerosene, the substitution of which by RR-based oils (e. g., rape seed oil) is subject of intensive investigations. 

Another group of effective sizes include alkyl ke-tene dimers (- fatty diketenes) and alkenylsucci-nic anhydrides. These products react with the OH-groups of the cellulose fiber. While rosin-based sizes can only by used in acid paper making processes, the cellulose-reactive sizes are used in neutral and alkaline paper making. The result is better sheet strength, reduced corrosion on the equipment, less salt in the effluent and better stability of the paper towards aging (archival paper). 

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