cellophane

cellophane

[sel-uh-feyn]
cellophane, thin, transparent sheet or tube of regenerated cellulose. Cellophane is used in packaging and as a membrane for dialysis. It is sometimes dyed and can be moisture-proofed by a thin coating of pyroxylin. There are several steps in the preparation of cellophane from raw cellulose. The cellulose is first treated with an alkali, e.g., sodium hydroxide, and mixed with carbon disulfide to form viscose (see viscose process). The viscose is aged for several days and then forced through a straight or circular slit into a dilute acid solution. The dissolved cellulose precipitates, and this regenerated cellulose has a lower molecular weight and a less orderly structure than the cellulose from which it is formed.

Cellophane is a thin, transparent sheet made of regenerated cellulose.

Cellulose fibers from wood, cotton, hemp, or other sources are dissolved in alkali and carbon disulfide to make a solution called viscose, which is then extruded through a slit into an acid bath to reconvert the viscose into cellulose. A similar process, using a hole (a spinneret) instead of a slit, is used to make a fibre called rayon. Chemically, cellophane, rayon and cellulose are polymers of glucose and contain the chemical elements carbon, hydrogen, and oxygen.

Cellophane was invented in 1908 by Jacques E. Brandenberger, a Swiss textiles engineer. After witnessing a wine spill on a restaurant tablecloth, Brandenberger initially had the idea to develop a clear coating for cloth to make it waterproof. He experimented, and came up with a way to apply liquid viscose to cloth, but found the resultant combination of cloth and viscose film too stiff to be of use. However, the clear film easily separated from the backing cloth, and he abandoned his original idea as the possibilities of the new material became apparent. Cellophane's low permeability to air, oils and greases, and bacteria makes it useful for food packaging.

Whitman's candy company initiated use of cellophane for candy wrapping in the United States in 1912 for their Whitman's Sampler. They remained the largest user of imported cellophane from France until nearly 1924, when DuPont built the first cellophane manufacturing plant in the US. In 1935 British Cellophane Ltd was established, a joint venture between La Cellophane SA and Courtaulds, which opened a major factory producing cellophane in Columbus, Ohio in 1937. Cellophane is also used to wrap gift baskets and flower bouquets.

Cellulose film has been manufactured continuously since the mid-1930s and is still used today. As well as packaging a variety of food items, there are also industrial applications, such as a base for such self-adhesive tapes as Sellotape and Scotch Tape, a semi-permeable membrane in a certain type of battery, as dialysis tubing (Visking tubing) and as a release agent in the manufacture of fibreglass and rubber products. The word "cellophane" has been genericized, and is often used informally to refer to a wide variety of plastic film products, even those not made of cellulose.

Cellophane sales have dwindled since the 1960s due to use of alternative packaging options, and the fact that viscose is becoming less common because of the polluting effects of carbon disulfide and other by-products of the process. However, the fact that cellophane is 100% biodegradable has increased its popularity as a food wrapping. It is also used in the making of bendy rulers, although those are not common.

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