670 CREATIVE CHEMISTRY All pyroxylin plastics suffer from the disadvantage of being extremely inflammable. It has been found that acetic acid can replace nitric acid in its action on cellulose and that the cellulose acetate thus produced is much less inflammable. Fig. 290. Two identical sheets of "Louverglas" placed at different angles. Abov-e it appears as transparent sheeting; below it appears translucent. (Courtesy of the E. I. du Pont de Nemours Company.) Cellulose acetate is marketed extensively as dress fabrics known generally as "acetates." The socalled "safety" motion-picture films are made from cellulose acetate. Many difficulties in the preparation of cellulose acetate products had to be overcome, but they are now rapidly replacing pyroxylin lacquers and plastics. The E. I. du Pont de Nemours and Company's "Plastacele" cellulose acetate plastic is an example. used in It is such materials as airplane cowlings, decorative jewelry, musical instruments, lamp shades, watch crystals, steering wheels, combs, bottle caps, and safety glass. "Tenite" is a plastic material made from cellulose acetate and cellulose acetate butyrate by the Tennessee Eastman Company. 4. Ethers. The Dow Chemical Company manufactures ethyl cellulose under the trade name of "Ethocel." This product is an ethyl ether of cellulose resulting from the interaction of ethyl chloride and alkali cellulose. It is colorless, odorless, tasteless, stable to heat and chemicals, slow-burning, flexible, and tough. These and other desirable properties make it one of the most versatile of cellulose derivatives for the manufacture of coating compositions, films, and plastics. 5. Decomposition Products. The production of charcoal by heating wood in an absence of air is an old industry. The by-products of this decomposition are acetic Fig. 291. Telephone equipment made from Tenite. (Courtesy of the Tennessee Eastman Corporation.) acid and wood alcohol (methanol). The synthesis of acetic acid from acetylene and the synthesis of wood alcohol (methyl alcohol) from carbon monoxide and hydrogen reduced the value of these
"BETTER THINGS" FROM CELLULOSE 671 products so much that the destructive distillation of wood has been greatly curtailed. Other processes for using cellulose as a raw material are being developed. For example, Friedrich Bergius has developed in Germany a commercial process for the production of edible sugars from sawdust. As the structure of cellulose becomes better known, it is certain that many other valuable materials will be made from it. Chemical Research Has Produced Materials Which Greatly Improve Fabrics Made from Natural Textile Fibers. The sensational creation of synthetic Fig. 292. The steering fibers must not obscure the story of the wheel of cellulose acetate is brilliant achievements of chemistry in im- only one of 200 plastic parts ,1 1 . ,.1 on the modern automobile. provmg the commonplace textiles. ,^ r t-l n i i- . ,„ „. ,,r ,1 (Courtesy of The Bakelite 1. Water-repelling. Water repellency differs from waterproofing in that, while Corporation.) the whole surface is rendered impervious to water in waterproofing, the surface remains porous in water repellency because each fiber is waterproofed. Water repellents render fabrics such as hosiery resistant to spotting by water. One interesting new finish of this type is the E. I. du Pont de Nemours and Company's "Zelan" durable water repellent, which is so resistant to laundering and dry cleaning as to remain effective throughout the useful life of the fabric to which it is applied. 2. Snagproofing. Wax emulsions and resin finishes lubricate textile surfaces of hosiery, thus decreasing their tendency to snag. 3. Wiltproofing. Collars which retain their shape without the use of starch before ironing them are made possible by sandwiching cellulose acetate or other types of resins between layers of fabric. 4. Creaseproofing. Crease resistance is imparted to cotton, rayon, and linen by the use of urea-formaldehyde resins (described in the next Section). 5. Fire-retarding. The latest and most satisfactory fire retardant is ammonium sulfamate. 6. Mildewproofing . Salicylanilide, a coal-tar derivative, prevents mildew. 7. Mothproofing. Compounds of fluorine and chlorine which will mothproof textiles have been discovered.