' i H i 680 CREATIVE CHEMISTRY compounds from the copolymer require very little or no plasticizer,' whereas most other synthetic resins require considerably greater quantities of plasticizing agents to make compounding and forming possible. Vinylidene chloride [ 1 I . C=C ! I I H CI I may be polymerized to produce long-chain compounds such as H CI I H H CI H CI H CI —C—C—C—C—C—C— CI H CI H CI ! A wide range of properties may be obtained by controlling the length of the chain or by adding another vinyl-type substance such as vinyl chloride CII. ' C=C II H H In this case the two substances polymerize together, forming such chain compounds as H CI H CI H CI H CI H CI —C—C—C—C—C—C—C—C—C—C— I H I H I H I CI I H I CI I H I CI I I H CI Such vinylidene resins are sold under the name of " Saran." They are used as binders for abrasive wheels, fishing leaders, and heavy-duty upholstery materials. Saran is highly resistant to chemicals, will not burn, and is odorless, tasteless, and nontoxic. It has extreme tensile strength and high abrasion resistance and toughness. Vinyl chloride may be polymerized by itself to produce a resin, but, as mentioned above, the addition of vinyl acetate confers many additional desirable properties. Glycolates, phthalates, or abietates are added to these resins to give them still more flexible, resilient, and » See p. 681.
SYNTHETIC PLASTICS 681 elastic qualities. Such added substances are called plasticizers. In this way strong, tough, durable, washable, beautifully clear, elastic sheets may be prepared from vinyl ester resins. These elastomeric sheets can be cut and sewed like any textile and may be joined by solvent or heat sealing. Such products as belts, suspenders, garters, watch straps and chains, and even wallets have been made of such "Vinylite" flexible sheeting. Two other uses for this sheeting are in air-conditioning ducts and collapsible tubes. They possess strength, durability, good appearance, novelty, and comfort. Comfortable and long-wearing shoes are made for both men and women. Such shoes would not require the "shining" that leather shoes do. There may be added to the above list of uses umbrellas, cosmetic bags, shoe bags, laundry bags, shower curtains, bridge-table covers, draperies, bedspreads, crib and bed sheeting, bibs, bathing suits, razor straps, and dog collars. Fig. 296. Elasticized Vinylite sheeting belt. (Courtesy of the Carbide and Carbon Chemicals Corporation.) Polyvinyl Alcohols Are Also Obtained from Coal, Air, and Water. Polyvinyl alcohols are white powders, odorless and tasteless. They are used as adhesives and paper coatings to give such strength to paper towels that theytmay be soaked in water, squeezed, twisted, and pulled with relatively little deformation. Paper containers may be greaseproofed and sized with polyvinyl alcohols. This material is also used as a softener and transparentizer in making glassine paper. As an adhesive polyvinyl alcohols are interesting because of their freedom from odor, color, taste, and attack by bacteria. They are used to manufacture white shoe dressings that will not rub off, pigmented inks, paints, water colors, printing pastes, etc. They also form tough, elastic, water-soluble films on metallic surfaces. They may be extruded to form tubes, rods, sheets, or threads. Tubing made from polyvinyl alcohols is impervious to oils and solvents and is resistant to flexing and vibration. Such tubing may thus replace metal tubes for fuel and oil lines in airplanes. Polyvinyl alcohol tubes transmit sound