Saponified Cellulose Acetate

Tn the last decades many attempts have been made to obtain attractive - materials by intimate mixing of two polymers with opposite or complementary properties. For example, the impact resistance of brittle polystyrene is increased by mixing with a rubber the wettability of polyacrylonitrile fiber is increased by mixing with hydrophilic saponified cellulose acetate, and the inconvenient flat-spotting of nylon-reinforced tires is suppressed by mixing stiffer polyester fibrils into the nylon fibers. In practically all cases these products acquire their final shape via the liquid state. Thus, the viscous properties of these liquid mixtures are important. 

Hydrophilic polymeric materials, e.g. cellophane and cuprophane, which are both regenerated celluloses have been used for aqueous applications. Other hydrophilic materials used include cellulose acetate (CA) or saponified cellulose acetate, poly(vinyl alcohol) (PVA), polyacrylic acid (PAA), polymethylmethacrylate(PMMA), copolymers of ethylene and vinyl acetate (EVA) or ethylene and vinyl alcohol (EVAL), of polycarbonate and polyether, and more hydrophobic materials such as polycarbonates (PC). 

Fortisan Saponified cellulose acetate Celanese Corp. 

The rayons are moderately stiff fibers with poor resiliency and wrinkle recovery properties. As in the case of cotton, resin treatments will effectively increase the resiliency of rayon. Often such treatments will tend to be more effective on rayon than on cotton due to the greater accessibility of the interior of rayon to the resin. The specific gravities of viscose and cuprammonium rayons are the same as cotton and vary between 1.50 and 1.54. Only saponified cellulose acetate has a markedly different specific gravity (1.30). 

The dry strength of regular-tenacity viscose and cuprammonium rayons are lower than that found for cotton, whereas high-tenacity viscose, poly-nosic, and saponified cellulose acetate rayons are significantly stronger than cotton. All rayons lose strength when wet and are more susceptible to damage while wet. 

Cellulose Diacetate. When preparing cellulose diacetate for dyeing, strong alkahes must be avoided in the scouring of acetate because the surface of the cellulose acetate would be saponified by such treatment. Many fabrics tend to crease and therefore requke open-width handling. Scouring is frequendy carried out on a jig or beam using 1.0 g/L of surfactant and 0.5—1.0 g/L tetrasodium pyrophosphate for 30 min at 70—80°C. 

Proof of grafting was presented through comparison of the solubilities of their saponified vinyl acetate and cellulose grafts and of the physical mixtures of the corresponding homopolymers. While from a cupriethyl-enediamin solution of the physical mixture pure cellulose is precipitated on acidification, the precipitate from the graft solution always contains constant amounts of polyvinyl alcohol, as proven by infrared spectroscopy. 

Cellniose Diacetate. When preparing cellulose diacclate for dyeing, strong alkalies must be avoided in the scouring of acetate because the surface of the cellulose acetate would be saponified by such treatment. 

Macromolecular transformations are also of scientific and commercial interest. They can be used for the manufacture of new compounds, particularly in cases where no monomer exists (vinyl alcohol as the enolic form of acetaldehyde) or where the monomer polymerizes with difficulty or not at all (e.g., vinyl hydroquinone). In these cases, derivatives such as vinyl acetate or vinyl hydroquinone ester are polymerized and the polymers are then saponified to poly(vinyl alcohol) and poly(vinyl hydroquinone), respectively. Other processes of industrial importance are conversions of inexpensive macromolecular compounds such as cellulose into new materials (cellulose acetate, cellulose nitrate, etc.), manufacture of ion exchange resins, and dyeing with reactive dyestuffs. All of these reactions lead to a definite product. If the degree of polymerization is retained, they are called polymer analog reactions. 

Footnote 5 300// cross-linked commercial continuous cast Acrysteel l-GP// continuous cast impact clear GPM gen purpose cast acrylic sheet clear Footnote 6 Cellulose acetate (partly saponified) 1.54 [4,14]... 

M.P. Schutzenberger produced cellulose acetate, with a degree of substitutions (DS) of about three by the reaction of acetic anhydride and cellulose in 1859. Cross and Bevan produced filaments and films from chloroform solutions of this triacetate but this was not an economical process. The commercial cellulose acetate rayon fiber process, based on acetone solutions of secondary cellulose acetate (DS=2), was developed and patented by G.W. Miles who partially saponified the triacetate in 1903 (11). 

Cotton Cuprammonium Regular rayon viscose rayon High-tenacity viscose rayon Saponified acetate rayon Cellulose acetate (secon- dary) Cellulose tri- acetate... 

A further type of regenerated cellulose is prepared by the hydrolysis of stretched cellulose acetate fibre. The resulting fibre, known as saponified acetate rayon, has high strength and low elongation (see Table 13.2). 

One common feature of the viscose, euprammonium, and carbamate processes is the chemically modified cellulose is regenerated into cellulose after the extrusion. Fibers made from these processes often are called rayon fibers. However, useful fibers can be produced by derivative methods without the regeneration of cellulose. Two important examples are cellulose acetate and cellulose triacetate fibers. Cellulose acetate can be obtained by aeetylation of cellulose with acetic acid and acetic anhydride with sulfuric acid as a catalyst. Cellulose triacetate, which is partly saponified to get the desired degree of substitution, is produced by a similar process. Both cellulose acetate and cellulose triacetate keep their derivative structure in final fibers. The major difference between these two fibers is that in cellulose acetate fibers, less than 92% but at least 74% of the -OH groups are acetylated, but in triacetate fibers, at least 92% of the hydroxyl groups are acetylated. 

Nitro-filter cloths are composed of cellulose nitrate, which is an ester of cellulose. Any chemical compound that will saponify the ester will destroy the cloth. Caustic soda or potash in strengths of 2% at 70° C or over alkali sulfides, polysulfides and sulfohydrates or mixtures of ethyl alcohol and ether, ethyl, amyl and butyl acetates, pyridine, ferrous sulfates, and other reducing agents are detrimental to the cloth. 

Hydrolytic degradation is especially important in polymers with hydrolyzable links between the CRUs. Thus, polyesters can be saponified to yield the starting materials from which they were formed. Acetal links in synthetic polymers such as polyoxymethylene, or in natural polymers such as cellulose, can be hydrolyzed with acids. However, the resistance to hydrolysis depends very much on the structure of the polymer for example, polyesters of terephthalic acid are very difficult to hydrolyze while aliphatic polyesters are generally easily hydro-... 

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