During the past forty years, disposable diapers have become an important part of the economy. Since the average baby uses at least ten diapers per day for an average of two years, the convenience of the product has made it a very popular as well as controversial item. A recent survey by Texas A&M University reported that 81 percent of the participants exclusively used disposable diapers, 15 percent used cloth and disposables, while just 4 percent used only cloth diapers.
The disposable diaper of today is composed of an inner layer of polyester that allows liquids to pass through to a layer of absorbent material, and an outer waterproof plastic layer of polyethylene film. The design was developed by many researchers through trial and error.
It is not clear who should be credited as the inventor of the first disposable diaper. The need for disposable diapers arose during World War II because of a shortage of cotton, which was used in traditional diapers. One of the first effective disposable diapers was created by Marion Donovan during the postwar baby boom. She is also credited with inventing the first plastic covering for traditional cloth diapers. Using this plastic covering (made from a shower curtain) and layers of tissue paper as an absorbent inner material, Donovan devised the new diaper in 1950. These first diapers were rectangular in shape, resulting in a bulky fit. In the 1960s, pulp was substituted for the paper, improving the absorbency of the diaper. The top sheets of the diaper were modified by using rayon. These diapers still were quite thick and included no tape for closure. By the 1970s the demand for disposable diapers had increased, and more improvements were added. New tapes were added for ease of fastening, and the shape was changed from rectangular to "hourglass."
During the early 1980s, modifications were made to respond to the demand for a better-fitting and biodegradable product. Starch was added to the outer sheet to enhance its biodegradability. Elastic was added to the
waist and to the leg openings for a better fit. Unfortunately this added a nonbiodegradable component to the product. A new tape system was developed to allow for several tapings and retapings without tearing the diaper. In response to a greater demand for a more environmentally friendly product, a new filler, cellulose mixed with crystals of polyacrylate, was developed. The cellulose is processed from pine trees and milled into "fluff pulp." The pulp consists of long cellulose fibers that provide a strong capillary effect, which helps to draw in the liquid. The surface tension binds the water once it has been absorbed.
The polyacrylate (known as a "superabsorbent polymer" or SAP by the diaper industry) is distributed throughout the fluff pulp. Another name for these crystals is Waterlock™. It is also used for plants to help retain water in the soil. The polyacrylate under pressure can hold an amount of liquid that is as much as thirty times its weight. This correlates to the compression (pressure) that occurs when a baby would sit or lie on the diaper. The polyacrylate allowed the manufacturers to reduce both the weight and thickness of the diaper by 50 percent and increase its absorbency.
The polyacrylate used in the diaper is a large-molecular-weight compound called a polymer. It consists of small repeating units called monomers. The length of the chain as well as the properties of the polymer may be changed by varying the reaction conditions. If two monomers are used in the synthesis of the polymer, the resultant polymer is referred to as a copolymer. The polymer used in disposable diapers is prepared by using acrylic acid as the monomer:
To obtain the properties needed for the diaper, sodium acrylate is used in the polymerization. The reaction is said to use "partially neutralized acrylic acid." The exact proportion of the two monomers (acrylic acid and sodium acrylate) present influences the character of the polymer formed. The length of the chains (represented by n ) also is modified by reaction conditions and can change the characteristics of the polymer.
In addition to forming the chains of polyacrylate, the chains are cross-linked. This is a process in which two or more chains are held together by other compounds in a network. Typical cross-linkers for this polymer include di- and tri-acrylate esters. The swelling and elasticity of the polyacrylate polymer depends on the structure of this network and the number of cross-links. The swelling capacity of the polymer decreases with increased cross-link density. After formation, the polyacrylate is dried and formed into microparticles of irregular shape that can be stored for a long time.
When these particles come in contact with water, urine, or other aqueous solutions , they quickly swell and absorb the liquid. Typically it takes no more than five to ten seconds for this to occur. The ability to swell and absorb the water is dependent upon the ionization of the acid groups on the polymer chain. The amount of water uptake increases with the increase in concentration of ionized groups. This is due to an increase in repulsion between the ionized groups in the polymer. This allows for a greater amount of swelling of the polymer. The amount of liquid that is absorbed depends partly on the nature of the liquid. The polymer absorbs more pure water than it does solutions. This means that more urine, an aqueous solution, would be absorbed than pure water.
Diapers continue to become thinner and more absorbent. During the 1990s a modification of the SAP was developed. It uses a surface cross-linker to reduce the "gel block" problem: If the absorbent is saturated with a liquid, it prevents the liquid from moving.
Independent inventors also are continuing to modify the diaper. Marlene Sandberg of Stockholm has constructed a diaper that is 70 percent biodegradable. She uses cornstarch in the preparation of the outer layer of the diaper. This allows her to reduce the amount of polyacrylate used by designing channels in the fill material that help disperse the urine. Other workers in the field dispute that the diaper is 70 percent biodegradable: They say the diapers will not degrade that much in a landfill—their ultimate destination.
As with all products, there are advantages and disadvantages to disposable diapers. The new polyacrylate gel has been linked to some side effects, including allergic reactions such as skin irritations, and to toxic shock syndrome. In addition, the dyes in the diapers have been linked to damage of the central nervous system, and disposable diapers may contain low concentrations of dioxin, a by-product of the bleaching process used in the production of the paper pulp found in the absorbent layer. Dioxin has been linked to liver damage and immune system suppression.
Disposables are also considered to be an environmental threat. Only some of the materials used in the diapers are biodegradable (the wood pulp and SAP). The polyethylene and polyester sheets are not biodegradable; neither is the elastic used for better fit, nor the polypropylene used for the tape that is employed as a fastener. Disposable diapers account for up to 2 percent of the total volume of landfills in the United States. The lifetime of the diaper in the landfill depends on several environmental factors: soil condition, groundwater flow, and the presence of other materials in the soil.
see also Materials Science; Polymers, Synthetic.
Catherine H. Banks
Buchholz, Fredric L., and Peppas, Nicholas A., eds. (1994). Superabsorbent Polymers, Science and Technology. Washington, DC: American Chemical Society.
Lewis, R. J., Sr., ed. (1987). Hawley's Condensed Chemical Dictionary, 14th edition. New York: Wiley.
Campbell, Todd. "Soaking It In: To Wash or Not to Wash? You Decide." ABC News.com 1999. Available from <http://www.abcnews.go.com/sections/tech/Geek/geek991011.html>.
"Diapers and Wipes: Frequently Asked Questions." Huggies. Kimberly-Clark Corp. Available from <http://www.huggies.com/DiapersWipes/faqs/materials.stm>.
Richer, Carlos. History of the Disposable Diaper. Available from <http://www.gpoabs.com.mx/cricher/history.htm>.
Schiff, Sherry. "The Diaper Dilemma." Waterloo Centre for Groundwater Research. Available from <http://www.science.uwaterloo.ca/earth/waton/s891.html>.
"What Is the Crystalline Substance Found in Disposable Diapers?" How Stuff Works. Available from <http://www.howstuffworks.com/question207.html>.
"Disposable Diapers." Chemistry: Foundations and Applications. . Encyclopedia.com. (June 28, 2017). http://www.encyclopedia.com/science/news-wires-white-papers-and-books/disposable-diapers
"Disposable Diapers." Chemistry: Foundations and Applications. . Retrieved June 28, 2017 from Encyclopedia.com: http://www.encyclopedia.com/science/news-wires-white-papers-and-books/disposable-diapers
Diapers and Toileting
Diapers and Toileting
For as long as there have been babies, there has been mess; but how parents have contended with that mess has changed over time and varied from culture to culture. Some Native American tribes packed grass under rabbit skins to contain their infants' waste. Inuits placed moss under sealskin. In Japan during the Edo era (1603–1868), farmers used an ejiko, a wooden bassinet layered with absorbent materials topped by a mattress with a hole cut out for the baby's buttocks. Urine was collected by the lower layers of ash, rags, and straw, and the baby stayed dry while the parents worked. In many warm places, even today, toddlers simply go naked below the waist or, as in China, have pants with a hole cut out of the bottom.
In Europe in the Middle Ages, babies were swaddled in long, narrow bands of linen, hemp, or wool. The groin was sometimes left unwrapped so that absorbent "buttock clothes" of flannel or linen could be tucked underneath. Often in warm weather swaddling bands were removed and children were left unclothed or swaddled only on top. After about a year, babies wore small dresses or blouses that fell to the ground with nothing underneath. A handful of ashes was thrown over the infant's excrement which allowed it to be easily swept away.
In the seventeenth and eighteenth centuries in Europe, babies were infrequently bathed or changed. When swaddling clothes were removed to attend to babies' waste, the infants' bottoms were usually just wiped without soap or water and then powdered with absorbent worm-eaten wood dust. Urine-soaked swaddling clothes were dried in front of the fire without being washed and then used again. Urine was believed to have disinfecting properties and filth was often considered protective for infants. It was not until the end of the eighteenth century that doctors began to recommend that cloths used as diapers be changed promptly.
In the mid-eighteenth century, philosophers such as Jean-Jacques Rousseau criticized swaddling as unhealthful. These criticisms altered the behavior of European urbanites and the wealthy but had little effect on the practices of the rural poor. English children were not commonly swaddled but dressed in diapers, underpants, and long woolen dresses with swaddling bands only around their abdomens. Swaddling cloth of oiled silk was developed in the eighteenth century in an attempt to prevent leaks.
A great advance in diapering was the invention of the safety pin, patented by Walter Hunt in 1849, but not widely used in place of the straight pin for securing diapers until the 1880s. By the late 1800s, infants in Europe and North America were wearing garments similar to the modern cloth diaper. A square of linen or cotton flannel was folded into a triangular or rectangular shape and held in place by safety pins. The diaper was covered with an absorbent pant called a "soaker" or "pilch," made of tightly knitted wool. In the late 1890s, rubberized pants were sometimes used to cover diapers. Diaper rash in the nineteenth century was commonly remedied with burnt flour or powdered vegetable sulfur.
One of the most common responses to the difficulties of diapering has been to toilet train early. At the end of the seventeenth century John Locke recommended putting babies on a "pierced chair"–a chair with a hole in the bottom under which a chamber pot could be placed. Some of these chairs had a space for a hot brick to help keep infants warm for the time, sometimes considerable, in which they were strapped to the chair while their mothers waited for them to "produce." Throughout the nineteenth and early twentieth centuries, parenting manuals commonly recommended that toilet training begin almost immediately after birth. Some manuals promised mothers that diapers could be dispensed with altogether within three or four months. After the 1940s, the idea of insistent early toilet training began to give way to the notion that the child should be the guide in toilet training. The child-guided process recommended putting off toilet training until the child was considerably older, meaning at least an additional five thousand diaper changes per child, according to one scholar's estimate.
Changing and cleaning diapers could be very laborious. Beginning in the twentieth century, mothers were encouraged by doctors and other child-rearing experts to wash diapers with soap and water and, by the 1930s, diapers were washed and then sterilized with a hot iron or boiled. Commercial diaper laundering services appeared in the United States in the 1930s. Cloth diapers were overlaid with a highly absorbent muslin, oilcloth, or gauze, or, in Great Britain, underpants made of sterilized latex. The Maternity Center Association, a nonprofit organization devoted to improving maternity care, advised parents that they could use "stork pants" with tightly gathered legs when they went visiting, but they were discouraged from using these regularly since they could irritate the baby's skin. In 1946 Marion Donovan invented a waterproof diaper cover made of a nylon parachute cloth that was reusable, leak-proof, and closed with snaps. She called it the "Boater" and when it debuted at Saks Fifth Avenue in 1949 it was an immediate success.
Some form of one-use diapers appeared as early as the 1890s, but they were not widely available (and affordable) until the 1960s. The modern disposable diaper was developed by Victor Mills and launched in 1961 under the brand name Pampers. Pampers were an immediate success, even though they initially came in only two sizes, had no tapes, and were quite bulky. Competition for the disposable diaper market soon took off and remedied these flaws. Some doctors worried that disposable diapers would adversely affect infants' development because of the bulk between the legs, but this fear was assuaged by hourglass-shaped diapers and then by the development of super-absorbent polymers, first patented in 1966, which allowed for the introduction of super-absorbent diapers in 1984. In 2001, disposable diapers were, on average, three times less bulky than they were in the early 1980s, significantly decreasing transportation, workforce, and storage costs. Since the early 1980s, disposable diapers have faced a great deal of criticism for their environmental impact, a subject which continues to ignite research and debate. Because of their efficiency, some have also accused disposable diapers of delaying toilet-training for young children.
See also: Child-Rearing Advice Literature; Hygiene; Pediatrics.
Bel Geddes, Joan. 1964. Small World: A History of Baby Care from the Stone Age to the Spock Age. New York: Macmillan.
Fontanel, Béatrice, and Claire d'Harcourt. 1997. Babies: History, Art, and Folklore. Trans. Lory Frankel. New York: Harry N. Abrams.
Gladwell, Malcolm. 2001. "Smaller; The Disposable Diaper and the Meaning of Progress." The New Yorker, Nov. 26: 74.
Kohno, Goro. 1987. "History of Diapering in Japan." Pediatrician 14 (suppl. 1): 2–5.
Thurer, Shari L. 1994. Myths of Motherhood: How Culture Reinvents the Good Mother. Boston: Houghton Mifflin.
Krafchik, Bernice. 2000. "Diapers: History and Development." Available from <http://cp.pdr.net/hostedfiles/docs/papc_diapers_site/history.htm>.
Richer, Carlos. 2000. "History of the Diaper." Available from <www.gpoabs.com.mx/cricher/history.htm>.
Caroline Hinkle Mcamant
"Diapers and Toileting." Encyclopedia of Children and Childhood in History and Society. . Encyclopedia.com. (June 28, 2017). http://www.encyclopedia.com/children/encyclopedias-almanacs-transcripts-and-maps/diapers-and-toileting
"Diapers and Toileting." Encyclopedia of Children and Childhood in History and Society. . Retrieved June 28, 2017 from Encyclopedia.com: http://www.encyclopedia.com/children/encyclopedias-almanacs-transcripts-and-maps/diapers-and-toileting