Cellulose general properties

Graft and block copolymers of cotton cellulose, in fiber, yam, and fabric forms, were prepared by free-radical initiated copolymerization reactions of vinyl monomers with cellulose. The properties of the fibrous cellulose-polyvinyl copolymers were evaluated by solubility, ESR, and infrared spectroscopy, light, electron, and scanning electron microscopy, fractional separation, thermal analysis, and physical properties, including textile properties. Generally, the textile properties of the fibrous copolymers were improved as compared with the properties of cotton products. 

Viscose was discovered by Cross and Sevan in 1892 during a programme of research on the general properties of cellulose. It is the sodium salt of cellulose xanthic acid. The acid, which does not exist in the free state, is ethyl hydrogen dithiocarbonate (1)... 

The synthesis and the general properties of these compounds have been reviewed extensively [1-15] and they will be recalled only when necessary to explain recent data. In this review, emphasis will be laid on papers dealing with cellulose derivatives used in the field of pharmacy, medicine, cosmetics and food, but applications will essentially be related to drug delivery. This presentation will be on a comparative mode between cellulose derivatives. The first two sections are concerned with all types of cellulose derivatives, while the following are each devoted to a special solubility-class of derivatives. 

General characteristics of cellulose Structure of cellulose Chemical properties of cellulose Welting and swelling Degradation of cellulose Effect of other factors on cellulose Substances accompanying cellulose Hemicellulascs Lignin... 

Cellulose, identified chemically as j8-l,4-glucan, is the most widely found natural polymer, constituting the permanent structure of plant cell walls. For the general properties and chemistry of cellulose itself the reader is referred to standard textbooks and recent reviews. 

Uses Crosslinking agent in melamine resin coating systems, general industrial finishes, coil-coating enamels, appliance finishes, useful with alkyd, polyester, thermosetting acrylic, epoxy, and cellulose resins Properties Gardner 2 max. clear, vise, liq. limited water-sol. dens. 10.0 Ib/gal vise. (G-H) X-Z2 flash pt. > 180 F 98% NV Cymel 350 [Cytecind.j... 

Many )ecies of woody plants are used for particular purposes, with their end use being directed by the properties of the wood and economic concerns. Generally, the functional use of wood products is determined by the hydrophilic, hydrophobic, dimensional, and ionic properties of the cellulosic fiber. Small diameter and mixed species of wood have limited uses and are thus low in value. If we could understand how to change the cellulose fiber properties of such materials, alternative sources of fiber could be better exploited and more valuable products made from mixed woody species or recycled fiber. 

Cellulose acetate butyrate (CAB) or cellulose butyrate is an ester of cellulose made by the action of a mixture of acetic acid and its anhydride on purified cellulose. It is used in the manufacture of plastics that are similar in general properties to cellulose acetate but are tougher and have better moisture resistance and dimensional stability. Cellulose acetate butyrate is used for pen barrels, steering wheels, tool handles, machine guards, and skylights. 

Partially purified (DEAE-cellulose) liver N-acetyltransferase from mature rapid acetylator rabbits has been described in some detail (Weber and Cohen, 1967 Cohen and Steinberg, 1967 Weber et al., 1968). The general properties given below refer to enzyme from this species except where otherwise noted ... 

The important features of rigidity and transparency make the material competitive with polystyrene, cellulose acetate and poly(methyl methacrylate) for a number of applications. In general the copolymer is cheaper than poly(methyl methacrylate) and cellulose acetate, tougher than poly(methyl methacrylate) and polystyrene and superior in chemical and most physical properties to polystyrene and cellulose acetate. It does not have such a high transparency or such food weathering properties as poly(methyl methacrylate). As a result of these considerations the styrene-acrylonitrile copolymers have found applications for dials, knobs and covers for domestic appliances, electrical equipment and car equipment, for picnic ware and housewares, and a number of other industrial and domestic applications with requirements somewhat more stringent than can be met by polystyrene. 

Weathering. This generally occurs as a result of the combined effect of water absorption and exposure to ultra-violet radiation (u-v). Absorption of water can have a plasticizing action on plastics which increases flexibility but ultimately (on elimination of the water) results in embrittlement, while u-v causes breakdown of the bonds in the polymer chain. The result is general deterioration of physical properties. A loss of colour or clarity (or both) may also occur. Absorption of water reduces dimensional stability of moulded articles. Most thermoplastics, in particular cellulose derivatives, are affected, and also polyethylene, PVC, and nylons. 

Since the changes in physical properties are often the impetus for grafting, it is necessary to briefly touch on this, in this section. A number of general reviews on grafting have also included some discussion on the changes in physical properties [126-129] that usually determine the field of applications. Some other reviews deal with certain properties and applications, such as sorbency [70] and ion exchange properties [130] of cellulose. 

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