Cellulose ester fibers Properties

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. 

The cellulose esters with the largest commercial consumption are cellulose acetate, including cellulose triacetate, cellulose acetate butyrate, and cellulose acetate propionate. Cellulose acetate is used in textile fibers, plastics, film, sheeting, and lacquers. The cellulose acetate used for photographic film base is almost exclusively triacetate some triacetate is also used for textile fibers because of its crystalline and heat-setting characteristics. The critical properties of cellulose acetate as related to appHcation are given in Table 10. 

Much helpful information on starch esterification methods and on the probable properties of starch esters may be obtained by examining similar reactions and esters in the cellulose field. This is because both starch and cellulose consist of polymerized glucose units capable of esterification to the triester stage, and because the superior ability of the cellulose esters to form plastics, films, fibers, and lacquers has promoted an accumulation of information on cellulose esters which far exceeds the present knowledge of starch esters. 

Several classes of polymeric materials are found to perform adequately for blood processing, including cellulose and cellulose esters, polyamides, polysulfone, and some acrylic and polycarbonate copolymers. However, commercial cellulose, used for the first membranes in the late 1940 s, remains the principal material in which hemodialysis membranes are made. Membranes are obtained by casting or spinning a dope mixture of cellulose dissolved in cuprammonium solution or by deacetylating cellulose acetate hollow fibers [121]. However, polycarbonate-polyether (PC-PE) block copolymers, in which the ratio between hydrophobic PC and hydrophilic PE blocks can be varied to modulate the mechanical properties as well as the diffusivity and permeability of the membrane, compete with cellulose in the hemodialysis market. 

This suggests that cellulose esters may be manufactured following a simplified esterification protocol in which steam exploded fibers are subjected to chemical modification followed by an optional separation of lignin at the end of the esterification procedure (Figure 8). The protocol is capable of generating an impure wood ester product with engineerable thermoplastic properties, or it may conversely be used to prepare a pure cellulose ester product, cleanly separated from a lignin ester polymer by appropriate solvent precipitation. 

Membrane filters are used to remove particulates from samples and solvents prior to HPLC analysis and also for the preparation of liquid samples, where no solvent is used. Typical materials of construction for membrane filters are usually synthetic polymeric materials, although natural substances, such as cellulose, and inorganic materials, such as glass fibers, are also used acrylic copolymer, aluminum oxide, cellulose acetate, glass fiber, mixed cellulose esters, nitrocellulose, nylon, polycarbonate, polyester, polyether sulfone, polypropylene polysulfone, PTFE, PVC, etc. The compatibility of the polymeric material with the solvents used must be a great concern of their different chemical properties. 

Sulfolane is used as a polymerization solvent for the production of polysulfones, polysiloxanes, polyphenylene ethers, and other polymers. Sulfolane is said to increase the reaction rates, afford easier polymer purification, and improved thermal stability. Sulfolane is a solvent for dissolving a variety of polymers for use in the fiber-spinning process. Cellulose and cellulose ester polymers can be plasticized with sulfolane to give improved flexibility and other physical property improvements [12,13]. Other application areas that have used sulfolane include electronic and electrical, textile-dye uses, curing of polysulfide sealant, and as a catalyst in certain synthetic reactions. 

Metall ic fibers are defined as fibers composed of metal, plastic-coated metal, or metal-coated plastic. Single-component metall ic fibers for textile usage are fine drawn filaments of metal which can be spun and woven on normal textile machinery. These metallic fibers possess the properties of the metal from which they are formed. Multicomponent metallic fibers are more commonly used in textiles and are usually made from flat aluminum filaments surrounded with or bonded between clear layers of polyester, cellophane, or cellulose ester or from polyester film which has been metallized through vacuum deposition of aluminum and then encapsulated in polyester. In general, the properties of these fibers resemble the properties of the plastic film used to form the multicomponent fiber. The fibers are generally weak and easily stretched but can be used for decorative purposes and for applications where electrical conductivity and heat resistance are important. Trade names for metallic fibers include Brunsmet and Lurex. 

The partially esterified acetate, propionate, and butyrate esters of cellulose also have proved to be useful. They can be made with a wide range of properties because of the latitude provided by varying molecular weight, ester content, and amount and type of plasticizer. The cellulose esters have been made into fiber, thickeners for coatings, and molded articles such as toys, combs, eyeglass frames, and cutlery handles. They have been extruded into pipe, formed into sheet, and used for a variety of decorative and protective laminates. 

Cellulose esters of carboxylic acids with 7c-electron structures, e.g. where R in the acyl chloride is a benzoyl, cinnamoyl, furoyl or thenoyl group, have been prepared. " The effects of these groups on the properties of cellulose, particularly on the absorption, transfer and localization of energy from ionizing radiations in cellulose, have been reported. Dependent on mechanical restrictions of the fibers during chemical modification and the DS of the products, many of the initial mechanical properties of the fibers are retained. 

Chem. Descrip. Ethox ated ester/cationic softener/lubricant blend Ionic Nature Nonionic/cationic Uses Water absorbent, softener for cellulosic fibers Properties Liq. 

A. solutions are well suited to be cast to biodegradable films and fibers from the unmodified state, in which the functional properties are enhanced with increasing amylose content. After derivatization with fatty acid (DS >1) the esters are soluble in organic solvents and show properties similar to cellulose esters. 

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