Cellulose acetate and triacetate

Many ceUulosic derivatives form anisotropic, ie, Hquid crystalline, solutions, and cellulose acetate and triacetate are no exception. Various cellulose acetate anisotropic solutions have been made using a variety of solvents (56,57). The nature of the polymer—solvent interaction determines the concentration at which hquid crystalline behavior is initiated. The better the interaction, the lower the concentration needed to form the anisotropic, birefringent polymer solution. Strong organic acids, eg, trifluoroacetic acid are most effective and can produce an anisotropic phase with concentrations as low as 28% (58). Trifluoroacetic acid has been studied with cellulose triacetate alone or in combination with other solvents (59—64) concentrations of 30—42% (wt vol) triacetate were common. 

Fig. 11. World production of cellulose acetate and triacetate fibers I, cigarette tow B, textile (74).

Other Cellulosics. Rayon is bleached similarly to cotton but under milder conditions since the fibers are more easily damaged and since there is less colored material to bleach. Cellulose acetate and triacetate are not usually bleached. They can be bleached like rayon, except a slightly lower pH is used to prevent hydrolysis. The above fibers are most commonly bleached with hydrogen peroxide. Linen, dax, and jute requite more bleaching and mil der conditions than cotton, so multiple steps are usually used. Commonly an acidic or neutral hypochlorite solution is followed by alkaline hypochlorite, peroxide, chlorite, or permanganate, or a chlorite step is done between two peroxide steps. A one-step process with sodium chlorite and hydrogen peroxide is also used. 

Cellulose acetate and triacetate fibres are brightened with disperse-type FBAs, including derivatives of 1,3-diphenylpyrazoline (11.19). These form a commercially important group of FBAs. If suitably substituted they can be applied to substrates other than acetate and triacetate. The commercially more important products of this type are used to brighten nylon and acrylic fibres. Their preparation and other aspects of pyrazoline chemistry are discussed in section 11.8. Examples of pyrazolines used to brighten acetate and triacetate... 

Cellulose acetate and triacetate may be used as plastics or spun into fibers for textiles. They are made by the reaction of cellulose with acetic anhydride. 

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. 

Cellulose Acetate and Triacetate Polymer. The production of acetate and triacetate polymer is accomplished by the esterification of high purity chemical cellulose, except for special plastic-grade acetates requiring low color and high clarity, where cotton linters are used... 

Cellulose Acetate and Triacetate Fibers. Polymer solutions arc convened into fibers by extrusion. The dry-extrusion process, also called dry spinning, is primarily used lor acelate and triacetate. 

Fine Structure of Cellulose Acetate and Triacetate Fibers.795... 

Cellulose acetate fiber was first marketed as artificial silk and found applications as tricot knits and woven fabrics in blouses, dresses, apparel linings, velvets, and decorative ribbons. The combined cellulose acetate and triacetate textile fiber production continued to grow until in 1971 it peaked at 426,000 MT worldwide. The impact of synthetic fibers, namely polyester and nylon, during the 1970s was significant and has gradually taken market share... 

Cellulose acetate and triacetate fibers have survived in the marketplace because they have certain unusual properties that demonstrate significant advantages over other polymerie materials. Cellulose acetate and triacetate textile fibers are luxurious. Fabrics made from them have an excellent hand, dye to brilliant, attractive shades, and are soft and comfortable. Regarding cellulose acetate and triacetate plastics and films, no other polymers can match the sparkling clarity possessed by these. For cigarette-smoke filtration, cellulose acetate offers a unique balance of properties including smoke removal efficiency and contribution to taste that makes it the standard of the industry. 

Overview of Fiber Properties for Cellulose Acetate and Triacetate... 

Moisture-regain curves for cellulose acetate and triacetate fibers compared with those of kier-boiled cotton are shown in Figure 11.5 [56,57]. The curves for acetate fiber are positioned only slightly below those for cotton and actually mesh for intermediate values of relative humidity. Since moisture regain relates to the comfort factor of fabrics, the curves explain why cellulose acetate, like cotton, possesses this important characteristic. 

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