"The Nylon Drama," by David A. Hounshell and John Kenly Smith Jr., Invention and Technology (Fall, 1988): 40-55. Reprinted with the permission of Cambridge University Press. Any reproduction or copying of this material in any format, beyond single copying by an authorized individual for personal use only, must first receive the written consent of Cambridge University Press.
The tension between a pure-science idealist and a pragmatic corporation resulted in an artificial fiber of historic importance and the biggest money-maker in the history of Du Pont.
On October 27, 1938, Charles Stine, a vice president of E. I. du Pont de Nemours, Inc., announced that nylon had been invented. He unveiled the world's first synthetic fiber not to a scientific society but to three thousand women's club members gathered at the site of the 1939 New York World's Fair for the New York Herald Tribune's Eighth Annual Forum on Current Problems. He spoke in a session entitled "We Enter the World of Tomorrow" which was keyed to the theme of the forthcoming fair, the World of Tomorrow.Images Courtesy of Hagley Museum and Library.
|Wallace Hume Carothers in his Du Pont lab in |
In the middle of Stine's talk, he proclaimed: "To this audience . . . I am making the first announcement of a brand new chemical textile fiber. This textile fiber is the first man-made organic textile fiber prepared wholly from new materials from the mineral kingdom. I refer to the fiber produced from nylon. . . . Though wholly fabricated from such common raw materials as coal, water, and air, nylon can be fashioned into filaments as strong as steel, as fine as a spider's web, yet more elastic than any of the common natural fibers."
Thinking that "strong as steel" meant indestructible stockings, the women at the forum burst into applause.
Twelve years earlier, on December 18, 1926, Stine, then the director of Du Pont's Chemical [ie., central research] Department, had taken the first step down the very long road to nylon by submitting to the company's executive committee a short memorandum entitled "Pure Science Work."
Stine wanted to undertake research with "the object of establishing or discovering new scientific facts," as contrasted with Du Pont's current research, which "applied previously established scientific facts to practical problems." He pointed out that "fundamental or pioneer research work by industrial laboratories was not an untried experiment" but rather had been successful in the German chemical industry and in the General Electric Company. He recognized that universities did a considerable amount of fundamental research but noted that there were some important gaps in their programs; as he put it, "applied research is facing a shortage of its principal raw materials."
He listed four reasons why Du Pont should spend its money on this new kind of industrial chemical research. First was the scientific prestige or "advertising value" to be gained through the presentation and publishing of papers. Second, interesting scientific research would improve morale and make the recruiting of Ph.D. chemists easier. Third, the results of Du Pont's pure-science work could be used to barter for information about research in other institutions. Fourth, pure science might give rise to practical applications. Although Stine personally believed that practical applications would inevitably result, he felt that his proposal was totally justified by the first three reasons.
|Two models in the Du Pont pavilion at the New York World's Fair|
play tug-of-war with a nylon stocking to dramatize its strength.
The executive committee waited until Stine submitted a more detailed proposal in March 1927. In this document he used the term "fundamental research" which perhaps the committee found more acceptable than "pure science." But Stine really did want to do pure science at Du Pont. To clarify the distinction between "pioneering applied" and "fundamental" research, he stated that the former "might result in something of great value or might come to naught. But the latter is bound to result in the discovery of new highly useful and in some cases indispensable knowledge." Investigation of the scientific foundations of chemical technology had to yield significant results in the long run. Science would improve on traditional knowledge.Stine got even more than he asked for. Beginning in April 1927, fundamental research was to receive $25,000 a month, much more than Stine could possibly spend for several years. As part of his 1927 budget, Stine received $115,000 to build a new laboratory for fundamental research, which Du Pont chemists quickly dubbed "Purity Hall." With the new building under construction, Stine began to look for 25 scientists to fill it.
|Carothers and Hill built this molecular still|
produce their first superpolymers in 1930.
From the outset Stine believed that his program would succeed only if he could hire "men of proven ability and recognized standing in their respective fields." But he realized that it would be difficult and maybe impossible to recruit such men, all of whom worked in academia and had developed specific lines of research. Alternatively he proposed to do what General Electric and
Bell Labs had done successfully: hire "men of exceptional scientific promise but [with] no established reputation. In this case the nature of their work can largely be determined by us."
|A technician pours chips of raw nylon|
polymer into a storage hopper.
By the end of 1927 he had eight men at work on several lines of fundamental research. He had hoped to have 15 men working on organic chemistry alone and to spend nearly half his budget on it. But by the beginning of 1928 he had succeeded in hiring only one man, a thirty-one-year-old instructor from Harvard University named Wallace Hume Carothers.
|Technicians inspect a reactor used to synthesize an intermediate chemical.|
The object of fundamental research at Du Pont was to discover new scientific facts, not to seek practical applications for existing knowledge. But the research was bound to yield significant results in the long run.
During his nine years at Du Pont. the brilliant but mercurial Carothers both made important contributions to polymer science and led the research effort that produced neoprene synthetic rubber and nylon. He had become interested in chemistry as a high school student in Des Moines. In the fall of 1915 he entered Tarkio College in Missouri as a science major and simultaneously accepted a position in the Commercial Department of the college. Later he assisted in the English Department. Carothers prided himself on his ability to write clear and forceful prose, a skill evident in his scientific papers. When his chemistry professor, Arthur M. Pardee, left Tarkio for the University of South Dakota, Carothers filled in as the chemistry instructor, though he was still an undergraduate. After graduating in 1920, he obtained a master's degree in organic chemistry at the University of Illinois. Then, joining Pardee in South Dakota, Carothers taught courses in analytical and physical chemistry to save enough money to return to Illinois for a Ph.D.
Back in Illinois in 1922, he soon became bored by the drudgery of graduate school. He wrote to a friend that "it contains all the elements of adventure and enterprise which a nut screwer in a Ford factory must feel on setting out for work in the morning." Only his research, which was driven by "the insatiable curiosity of the true scientific spirit," kept him jumping the hurdles toward his Ph.D. For the 1923 - 24 year, the college awarded him the Chemistry Department's most prestigious fellowship, the extra income from which Carothers used to support his passions for billiards and coffee. He completed his doctorate in 1924 and remained at Illinois as an instructor for two years until he was hired by Harvard University. Although Carothers believed Harvard was the "academic paradise" for teaching, he really did not like to teach. Soon Du Pont offered him a job that ostensibly entailed nothing but research.
Carothers resisted Stine's recruitment efforts until he was absolutely sure that fundamental research meant pure science. When he asked if he could continue his work on the thermal decomposition of ethylmetal compounds, Stine replied that at Du Pont Carothers could work on whatever he pleased, but the growth of his group would depend on his "capacity for initiating and directing work that we consider worthwhile undertaking." What Stine wanted him to do was research in the emerging field of polymer science.
In a letter to Stine, Carothers detailed his concerns. He said that his overriding desire was for scientific advancement; therefore, he had to weigh Du Pont's offer against his present position. He worried that at Du Pont he might have to "suppress the development of an investigation." Conversely, he felt that he would have more and higher-quality research assistants at Du Pont than at Harvard. At the personal level Carothers wondered how he would fit in at Du Pont, especially since he suffered "from neurotic spells of diminished capacity which might constitute a much more serious handicap there than here."
Stine dispatched one of his assistants, Hamilton Bradshaw, to Cambridge to see Carothers. In the intellectual Bradshaw, Carothers found a kindred spirit. They must have talked about the challenges offered by polymer research and the kind of support that Du Pont promised. Also Bradshaw raised Du Pont's salary offer of five thousand dollars versus thirty-two hundred at Harvard, by 20 percent. Ten days later Carothers decided to join the Du Pont Company.
Writing to Bradshaw shortly after accepting the position, Carothers set down his ideas about polymerization. His discussion contains the basis of the classic research that he did at Du Pont. At the time, German chemists were debating whether polymeric substances were held together by the same forces that operate in smaller molecules or whether some other kind of force peculiar to these substances was involved. Hermann Staudinger began to publish articles asserting that polymeric molecules were practically endless chains held together by ordinary chemical bonds. Carothers espoused this point of view and devised a scheme to prove it. He wrote Bradshaw: "I have been hoping that it might be possible to tackle this problem from the synthetic side. The idea would be to build up some very large molecules by simple and definite reactions in such a way that there could be no doubt about their structures."
In the weeks following his move to Wilmington, DE, in February 1928, Carothers wrote to his friend and fellow chemist John R. Johnson: "A week of the industrial slavery has already elapsed without breaking my proud spirit. Already I am so accustomed to the shackles that I scarcely notice them. Like the child laborers in the spinning factories and the coal mines, I arise before dawn and prepare myself a meager breakfast. Then off to the terrific grind arriving at 8 just as the birds are beginning to wake up. Harvard was never like this. From then on I occupy myself by thinking, smoking, reading, and talking until five o'clock."
Because Carothers was a well rounded person with numerous talents and interests, including art, sports. politics, and music, he quickly made many friends in Wilmington. He appeared to be a stereotypical oddball genius only to those who did not know him well.
|An early sale of nylons, in a Wilmington, Delaware,|
department store in 1939.
Seeking to resolve the controversy over polymerization, Carothers proposed to build long-chain molecules one step at a time by carrying out well understood chemical reactions. He chose one of the simplest reactions to test his hypothesis: Alcohols reacting with acids to form esters. He added a new twist, though. He reasoned that if each reacting molecule has only one alcohol or acid group, then one reaction is all that can occur. But if the molecules have a group capable of reaction, at each end, then the molecules can continue to react, building up a long chain in the process. Reacting compounds that had an alcohol group on each end with analogous acids, he made polyesters that contained up to twenty-five alcohol-acid pairs and had molecular weights between 1,500 and 4,000.
|A Du Pont film foresaw a future domestic environment|
of nylon, rayon, and Lucite.
Studying these and other related types of compounds, Carothers produced a thorough, logical, and massively documented case that polymers were just ordinary molecules, only longer. His co-worker Julian W. Hill later recalled that this work "finally laid to rest the ghost . . . that polymers were mysterious aggregates of small entities rather than true molecules." Carothers published his findings in a landmark paper in Chemical Reviews.
|At the 1939 World's Fair, a knitting machine|
produced nylons for public display.
By the end of 1929 Stine felt that his fundamental research program had been "marked by excellent progress" since "publication of results has occasioned favorable comment from numerous sources, and several of our men are earning increasing recognition in the scientific world." Carothers now had eight men working for him. Most of them had come straight from graduate school.
In the history of industrial research, April 1930 was a mensis mirabilis. Within weeks of each other, chemists in Carothers's group produced neoprene synthetic rubber and the first laboratory-synthesized fiber. These results were not the stated or implicit goals of Carothers's research; in retrospect, the discovery of the fiber was the more predictable event.
Neoprene was discovered incidentally during a project initiated to study the chemistry of an unusual compound, a short polymer consisting of three acetylene molecules, divinylacetylene (DVA). Several years earlier Du Pont researchers had tried unsuccessfully to make synthetic rubber from DVA. In early 1930 Carothers was asked to explore its chemistry by the new assistant director of the Chemical Department, Elmer K. Bolton, who had recently come from Du Pont's Dyestuffs Department, where he had earlier directed the synthetic-rubber research.
A crash program brought nylon out of the laboratory and into the marketplace in less than five years. Neoprene and nylon were both exceptional discoveries, but their development and commercialization were just as exceptional.
The major thrust of Carothers's work seems to have been to prepare and polymerize very pure DVA. When the chemist Arnold Collins, working under Carothers, produced clear films instead of the normally yellow ones, Carothers decided to attempt to isolate and identify the impurities in the crude DVA that might cause the yellowing. Upon distilling the crude DVA, Collins recovered a liquid that preliminary analysis suggested was a new compound. On April 17 he recorded in his laboratory notebook that an emulsion of the new liquid had solidified "to white, somewhat rubber-like masses.They sprang back to original shape when deformed but tore easily." This was the first sample of neoprene.
Another Du Pont lab soon took over the development and commercialization of neoprene. By the summer of 1930 Carothers was busy exploring the ramifications of the other discovery of April 1930. Julian Hill discovered a synthetic fiber while attempting to produce chains longer than anyone had ever prepared in the laboratory. Carothers had been building long polymer chains by a reaction of a carboxylic acid with an alcohol to give an ester. But by the end of 1929, the polyesters seemed to have hit a size limit at molecular weights of 5,000 to 6,000. Carothers decided that water, formed as a byproduct in the ester-forming reaction, was hydrolyzing ester groups back to acid and alcohol and that the molecular weight limit reflected an equilibrium between the forward and backward reactions.
The key to building longer molecules was to find a way of removing that water. Carothers and Hill constructed a device called a molecular still. The idea was to make the equilibrium polymer in the usual way and then to finish the reaction in the still, in which a cold surface trapped water molecules from just above the polymer and removed them from the mixture. Hill began heating an unusual acid-alcohol pair, because he and Carothers had decided that the reaction of a sixteen-carbon chain acid with a short three-carbon chain alcohol would promote the formation of longer molecules. While removing a sample of the resultant product from the still, Hill observed that the molten polymer could be drawn into fibers. He then made an important and unexpected discovery: that after being cooled, these pliable filaments could be stretched or "cold drawn" to form very strong fibers. Further tests on the sample showed that it had a molecular weight of over 12,000, far higher than any previous polymer.
Encouraged by this result, the researchers tried new combinations. The so-called 3-16 polyester and related ones proved to be unsuitable for textile fibers because they melted below 100 degrees Centigrade, were partially soluble in dry-cleaning solvents, and were sensitive to water.
By this time the invention of neoprene and these promising but impractical synthetic fibers was helping push fundamental research toward more clearly defined goals. Elmer Bolton was promoted to chemical director in June 1930, and Stine moved up onto the corporate executive committee. This brought about an immediate change in research philosophy and style. Bolton had opposed Stine's fundamental research program at its inception. Now it became his responsibility. He believed that fundamental research should be more closely directed or managed to give Du Pont direct competitive advantages. Whereas Stine had maintained that fundamental research was justified by the scientific prestige it would bring the company, Bolton emphasized the fourth and originally nonessential reason, "practical applications."
Wishing to publish his synthetic fiber findings, Carothers encountered opposition from Bolton's new assistant, Ernest B. Benger, who said that "on the basis of the possible great importance of the work . . . I have taken the attitude that the work should not be published and that our position should be protected by a well planned patent program." Carothers responded to Benger by suggesting that he had made unilaterally a rather important change in policy. As a compromise, Carothers waited until the patents were filed before publishing his paper a year later.
Even though the polyesters' melting points were too low, Benger and Bolton were excited by the fact that, unlike other fibers, they retained nearly all their strength when wet and had an elasticity that only silk could match. Encouraged, Carothers and Hill soon decided to try the chemically analogous polyamides, compounds made by combining an acid and an amine. It was known that simple amides melted at higher temperatures than the corresponding esters. So Carothers and Hill tried to make fibers from a few compounds of this type. Nylon is a polyamide, but in 1930 no satisfactory fibers could be produced, and Carothers and Hill soon gave up on polyamide fibers. Carothers had run out of patience and ideas for fibers. Besides, the work was getting fairly far afield from the kind of scientific exploration he enjoyed. He was unhappy about his lack of scientific progress and felt frustrated because he was not sure what Bolton expected from him.
As the economic situation deteriorated in the deepening Depression, Bolton tightened the reins on the fundamental research groups, which had already begun to devote much more time to applied subjects. The elite group of chemists that Stine had set up in Purity Hall was losing its special status. Carothers wrote: "The only guide we have for formulating and criticizing our own research problems is the rather desperate feeling that they should show a profit at the end. As a result I think that our problems are being undertaken in a spirit of uncertainty and skepticism." He suggested that fundamental research should again be guided by scientific, not commercial, considerations. Pure science researchers should keep the company up to
date on the latest analytical techniques and equipment, perform quick evaluations of ideas, and act as internal consultants for problems anywhere in the company.
|Nylon Notre Dame football pants, from 1941,|
and a 1949 all-nylon flight suit.
Carothers had established enough of a reputation for himself, both inside and outside Du Pont, that he could continue to work on his scientific studies, in spite of his concerns about what management expected from him. He followed his theoretical interests in the mechanism of polymerization, moving his research away from linear fiber-forming superpolymers toward the study of cyclic compounds consisting of eight- to 20-carbon-atom rings, which he found could be made in the molecular still.
His work on large-ring compounds completed his classic researches on polymerization and marked the end of his major scientific studies. In 1933 Carothers began casting about for new research areas but seemed unsure about what he wanted to do. Bolton saw Carothers's vacillation over research topics as an opportunity to encourage him to renew efforts on synthetic fibers. After a period of sporadic activity, the fiber work had come to a halt in the middle of 1933. Carothers had stopped the research because the problem appeared to be inherently unsolvable. He reasoned that the desired end-product properties, high melting point and low volubility, were the same ones that made the spinning of fibers impossible. There did not seem to be any way around this obstacle. He hypothesized that "if there were some means of spinning and synthesizing [the polymer] at the same time, as perhaps a silkworm may use, then it might be possible to get around this difficulty." But these ideas did not spur him to action.
The development of a new synthetic fiber remained at the top of Bolton's list of research priorities, and he kept trying to get Carothers to put at least one man on the problem. So early in 1934 Carothers began a new attack on it, and he determined that the obstacles that blocked the pathway could be overcome. The two problems he faced were the unreliability of the molecular still and the melting points of polyamides, which were apparently too high for them to be spun into fibers. To solve the first problem. Carothers thought that a superpolymer could be prepared without using the still if he used a carefully purified amino acid ester rather than the acid itself. To lower the melting point, he considered using a long-chain starting compound.
On March 23, 1934, Carothers suggested to one of his assistants, Donald D. Coffman, that he attempt to prepare a fiber from an aminononanoic ester. After spending five weeks preparing the compound, Coffman quickly polymerized it and was convinced that he had made a superpolymer because upon its being cooled, it had characteristically seized the walls of the flask and shattered them. The following day, May 24, 1934, Coffman drew a fiber from the four grams of polymer that he had made. He recorded in his notebook that he "heated [it] in a bath at 200oC just above its melting point. By immersing a cold stirring rod into the molten mass, upon withdrawal a fine fiber filament could be obtained. It seemed to be fairly tough, not at all brittle and could be cold-drawn to give a lustrous filament."
In retrospect the development of nylon appears to be the solution of thousands of small problems; but this kind of engineering could not even begin until after the big decisions were made about how nylon was to be manufactured.
Another sample yielded a "fiber having very good strength." These were the first nylon fibers, although the nylon that was eventually commercialized was a different polymer. The term nylon was later coined to designate a broad class of polymers: linear polyamides. Although the future of the product was not apparent at this moment, the high melting point of the new fiber led everyone to recognize that a practical synthetic fiber was at least technically feasible.
Not long after, Carothers went into an unusually severe depression, but after several months he recovered and tried to go back to work. In the next two years his bouts of depression became more frequent and severe. They culminated in the summer of 1936 in a major breakdown, from which he never recovered. Personal problems, including the sudden death of his beloved sister, compounded his difficulties. Finally, on April 29, 1937, three weeks after the basic nylon patent application had been filed and two days after his forty-first birthday, Carothers committed suicide with cyanide in a Philadelphia hotel room.
In the years just before his death, Carothers had become obsessed with the idea that he was a failure as a scientist. It is true that by 1933 he had worked out most of the ramifications of his one big idea. Perhaps his inability to come up with another one exacerbated his problems. It is equally probable, though, that he was despondent because his mental state had affected his scientific creativity. Elected to the National Academy of Sciences in 1936 and a potential Nobel Prize candidate, Carothers stood with a select few, very near the pinnacle of his profession. Bolton stated that "Carothers read from the depths of organic chemistry such as I have never seen." And Bolton had known many of the great ones.
Carothers's illness and the staff needs of nylon development gave Bolton additional opportunity to bring Stine's fundamental research division back into the fold of standard industrial research. Soon it was "reported, reviewed, supervised, and administered in much the same manner as other lines of work." Stine's now virtually defunct program had "succeeded"--in producing neoprene and nylon--because the company had hired Carothers, and Stine had encouraged him to work on polymers. But then Bolton had arrived at the proper moment to reorient the work toward an important technical objective. Had Carothers been left entirely on his own, as Stine had envisioned, nylon would probably not have been discovered and developed. Clearly tension existed between the pure-science idealist Carothers and the pragmatic Bolton, but nylon emerged from this tension.
Neoprene and nylon were first-rate achievements because the new substances were the first ones to have properties that excelled their natural analogues to any significant extent. Neoprene resisted degradation by oxygen, oil, and gasoline, and nylon was stronger and more abrasion-resistant than silk. The Du Pont Chemical Department's management believed neoprene and nylon had the potential to become outstanding products. However, the tasks of development and commercialization were formidable. From the preparation of the intermediate chemicals to the processing of the polymer into useful products, Du Pont had very few technological precedents to follow. At the heart of both production processes would be the reaction of the intermediates to form the solid polymers. In the mid-1930s there were no commercially produced synthetics that required the extent of control over the polymerization reaction that neoprene and nylon demanded. Therefore, Du Pont had to develop most of this technology itself, drawing upon all its deep and broad technological skills to achieve success.
At the same time that Du Ponts researchers were developing processes to make these new products, others were investigating strategies for commercializing them. Both neoprene and nylon had to fit into existing fabrication networks. The former was sold unprocessed to rubber fabricators, and the latter in the form of filaments to textile companies. Du Pont had to do the spinning step with nylon because the silk throwers were incapable of adapting to the new technology. Both neoprene and nylon were exceptional discoveries, and their development and commercialization were equally exceptional.
A crash program brought nylon out of the laboratory and into the marketplace in less than five years. There are two principal reasons why it was developed so effectively. One was the early decision that full-fashioned silk hosiery would be the first large market for the new material. Du Pont's management exercised considerable restraint by not yielding to the enthusiasm of researchers who saw nylon replacing, among other things, cellophane, photographic film, leather, and wool. Each year about seventy million dollars' worth of silk went into stockings, which were knitted into eight pairs per American woman per year; by focusing directly on this one market, Du Pont avoided having conflicting demands made on the research personnel who were trying
to develop a production process and on the sales development people who were working with textile manufacturers to evaluate nylon's performance.
|Early synthetic couture: an elegant nylon lace dress from 1940.|
The second way Du Pont kept the development of nylon moving was by focusing on one process for each production step. The research managers constantly put all their eggs in one basket. Of course, this strategy can lead to disaster if a particular approach proves unworkable. Fortunately for Du Pont, its managers exercised skillful judgment and had enough perseverance that no major lines of work had to be abandoned. Expediency ruled. Some of the initial equipment. according to Crawford H. Greenewalt, who oversaw much of the work, accomplished its tasks through "brute force and awkwardness." Still, the processes worked and produced nylon at a cost less than that of silk.
This get-a-workable-process approach to development depended heavily on Du Pont's impregnable patent position. Because nylon was unquestionably a Du Pont invention, the company did not have to worry about being
undercut by competitors. To make money it was not necessary to have the best possible process but just to have one that worked. As long as nylon could be made at a reasonable cost, improvements could wait.
|A nylon Stars and Stripes made by the Dettra|
Flag Company of Pennsylvania in 1946.
In the summer of 1934 the fiber project became the major focus of activity in Carothers's group. Several of his assistants began preparing polyamides from virtually every combination of dibasic acid and diamine with between two- and ten-carbon-atom chains. Of the eighty-one possible compounds, only five looked promising; eventually 6-6 (the numerical designation comes from the number of carbon atoms in the diamine and the dibasic acid, respectively), first prepared by Gerard J. Berchet on February 28, 1935, became Du Pont's nylon.
The early assessments of nylon showed that major problems would have to be solved. Only one of the two intermediate compounds, adipic acid, was produced on a fairly large scale, and that was in Germany. The other one, hexamethylenediamine, was a laboratory curiosity. Also, methods of controlling the polymer chain growth had to be developed, and once a satisfactory polymer had been made, it had to be converted into a fiber.
Du Pont's fiber-spinning technology had been developed for the manufacture of rayon and acetate, which did not melt and had to be spun from solutions. The Chemical Department decided to try a potentially simpler, faster, and cheaper process: melt spinning. This entailed melting the solid polymer to a honey like liquid that would be driven under pressures through a spinneret, which consisted of a number of very small holes in a metal plate. The extruded filaments would form solid fibers upon cooling.
Until they had a better idea how the product was going to be used, the developers did not give too much thought to the problems that would occur after the very fine filaments had been twisted together (as is done with silk) in bundles of twenty or thirty to make a textile fiber. Ultimately nylon had to be tested on standard textile machinery and put through commercial finishing processes.
After the major process steps had been conceptualized, teams of chemists and engineers could be assigned to work on each one. As new problems were recognized, the work was further subdivided. In retrospect, the development of nylon appears to be the solution of thousands of small problems, but this kind of engineering could begin only after the big decisions were made about how nylon was to be manufactured.
The development project can be split into three periods. In the year following Bolton's decision in July 1935 to commercialize nylon 6-6, work centered on determining whether it could feasibly become a commercial success. When Du Pont decided that nylon did show promise as a new kind of textile fiber, the second phase of development began; it lasted roughly from the sum
mer of 1936 until the end of 1937. In this phase nylon had to be shown to be practicable not just feasible. Also, the critically important decision was made then to concentrate on producing high quality yarn for full-fashioned hosiery. Finally, after learning that a satisfactory or maybe superior product could be made, Du Pont turned its. activities toward making yarn with uniform properties on a larger scale. With bigger samples of yarn to knit, the textile companies could run nylon under standard commercial conditions.
|A 1949 advertisement in Life Magazine sings the praises of nylon products.|
In the feasibility stage of development, the most immediate, if not the most important. problem was to work out a scheme for making the intermediate chemicals, especially hexamethylenediamine (HDA). HDA was very difficult to manufacture, requiring a multistep synthesis. Once several pound-batches of intermediates became available, experiments on polymerization started. The major goal then became to find methods of producing polymer that would make uniform fibers. This meant stopping the reaction at a precise moment to control the polymer's molecular weight. After considerable experimentation, Wesley R. Peterson discovered that the addition of small amounts of acetic acid would regulate the extent of polymerization. This was another "simple" solution that required considerable time and effort to be discovered.
|Before nylon: a 1923 ad for silk stockings.|
|Toothbrushes of the new fiber in a 1939 ad.|
The phrase "coal, air, and water" became associated with nylon and the transforming magic of science. The idea that stockings could be made from these ingredients seemed to many a modern miracle. It was the new alchemy.
Besides the HDA process and standardization of the polymer, the other major problem Du Pont faced in the early part of the development was that of spinning the polymer into fibers. At first, both melt and solution spinnings were tried. In the latter process the nylon polymer was dissolved in hot phenol or formamide, and the hot, syrupy solution was pumped through a spinneret. As the filaments emerged from the holes, the solvent evaporated and solid fibers were formed. This process looked unpromising because of the hazards and expense of handling and recovering the solvents. Melt spinning had the appeal of simplicity, but it required developing a new technology for precisely metering a molasses-like fluid to the spinneret at a temperature of about 260 degrees centigrade. Also, at its melting temperature some nylon polymer decomposed, and the extruding filament broke whenever the resulting gas bubble went through a spinneret hole. A practical continuous spinning process required that filaments be spun in very great lengths without breaks. By early 1936, even though melt spinning was still far from being a workable process, work on solution spinning was discontinued.
By the summer of 1936 Du Pont was ready to move nylon into a bigger scale of development. The company's Rayon Department reported that it considered the new fiber "a high quality yarn superior to natural silk" that would have a large market at two dollars a pound, roughly the price of silk. Preliminary estimates showed that nylon yarn could be produced for eighty cents a pound in a plant making eight million pounds a year. Even a very small plant could make money. On the basis of these optimistic forecasts, the research managers decided to expand the company's nylon-manufacturing capacity from two to one hundred pounds a day in order to improve the process and provide material for extensive testing. Nylon had entered its second phase of development. It looked good; now was the time to prove that it was so.
The Chemical Department constructed a glass melt-spinning assembly so that direct observation of the melted polymer would be possible. Experiments with the glass cell confirmed that decomposing polymer gave off gas bubbles that broke the fiber upon passing through a spinneret hole. Two principal researchers soon concluded that if the polymer kept under pressure, the bubbles would dissolve harmlessly into the molten mass. This idea worked and removed the major obstacle to the commercialization of melt spinning. By May 1937 continuous spinning times had been increased from ten to eighty-two hours.
Du Pont's development team had now made significant strides toward its goal of producing a standard and uniform product, but no yarn had been knitted into stockings. The first test came in February 1937, when Everett Vernon Lewis, a Rayon Department research chemist, took a few carefully measured skeins of yarn for a knitting test to the Union Manufacturing Company in Frederick, Maryland. Lewis later recalled that the security precautions that his management insisted upon were more stringent than those he encountered later in the Manhattan Project. On the train he never left the skeins, and after the test was over he gathered all the scraps and weighed them to make sure that no fiber was missing. The Frederick hosiery manufacturer experienced difficulties with the new fiber in nearly every production process. lt did not come off the spools properly; it snagged on the knitting machines; and after being dyed, it looked like a wrinkled mess that had "a not too pleasant gray color roughly approximating gun metal." Undaunted, Lewis attributed these difficulties to inexperience with a new material.
Du Pont soon learned that quality requirements were very high for full-fasioned hosiery yarn. Further testing was done at the Van Raalte mill in Boonton, NJ, and the first experimental stockings were made in April. By July 1937 Van Raalte had knitted enough material to give Du Pont some definite feedback. The yarn performed quite well; the outstanding defect was the tendency of the stockings to wrinkle during dyeing and the other finishing operations. These wrinkles "completely destroyed the uniform appearance of the stocking." A few months later it was discovered that these wrinkles could be eliminated by steam treating the stocking before dyeing.
Thanksgiving and perhaps Christmas came early for Du Pont in 1937. The Van Raalte mills had started turning out "full-fashioned hosiery excellent in appearance and free from defects." These stockings were virtually indistinguishable from their silk counterparts. And Du Pont management had in hand the results of a report on the reaction of women to nylon: The experimental stockings were very durable, but they wrinkled easily and were too lustrous and slippery. By now Preston Hoff of the Rayon Department, an earlier skeptic, found that "as the data accumulate, they continue to support our belief that in [nylon] we have a product that surpasses rather than approaches the natural one." He thought that many of the production problems would be solved in six months.
|The huge demand for nylons after World War II|
resulted in melees like this one in 1941.
|An unabashed customer sits|
on a curb to try out her new sheers in 1945.
But before a commercial plant could be built, Du Pont's management decided that a middle-size pilot plant was necessary. The executive committee's authorization of a pilot plant, on January 12,1933, signaled the end of the second phase of development. Nylon had been shown to be practicable. Now it had to be proved on a commercial scale. Whereas earlier efforts had centered on making one good stocking, the focus of attention moved toward the production of millions of pairs. An experimental unit about a tenth the size of the projected full-scale units was designed to produce 250 pounds of nylon yarn a day.
|Hundreds of women wait in line on a cold December morning in 1945 to buy|
hosiery at a New York City shoe store.
When the pilot plant was authorized, one problem began to look much more formidable than before. Silk filaments have a natural coating, sericin, that protects the fibers during textile processing. After the knitting is finished, the, coating, known as size, is removed with boiling water. Of course, nylon had no natural size. Du Pont needed to find a material that would form a protective film, be removable in hot water, not discolor the yarn, apply conveniently, and not accumulate on the knitting needles.
The size problem took many months trial-and-error work to solve. Working frantically, researchers in a number of departments contributed to the formulation of a new four-component size for nylon. This type of industrial research, though not glamorous in any way, proved absolutely necessary for the successful development of nylon. The elimination of the nagging size problem occurred just when Du Pont's first full-scale nylon plant, in Seaford, Delaware, was beginning production.
The Seaford plant began operation in January 1940. But from the start it could not make enough nylon to satisfy the large demand that had been generated since the company's public announcement of its new product.
When the war ended and women began to demand nylons again, their demand greatly exceeded supply for two years. Newspapers ran stories with headlines such as "Women Risk Life and Limb in Bitter Battle over Nylons."
Before it couldintroduce its new fiber, Du Pont had to come up with a name for it, and a committee was formed to do so. The company's president, Lammot du Pont, liked Delawear or neosheen. Another executive, Ernest Gladding, threw in Wacara, a play on Carothers's name, and later norun, which would have caused problems because nylon stockings did run. He then turned norun around to nuron but thought that sounded like a nerve tonic. So he changed the "r" to an "1", making it nulon. This apparently was very similar to an existing trademark, and Cladding realized that advertisements would refer to "new nulon," a redundant-sounding phrase. Next, he changed the "u" to an "i" and got nilon, which unfortunately has three pronunciations: "nil-lon", "nee-lon", or "nigh-lon". The last was chosen. Instead of registering nylon as a trademark, Du Pont made it a generic word that anyone would be free to use. The company's negative attitude toward trademarks had been engendered by the loss of its trademark for cellophane in 1937. The fact that hosiery became known as nylons probably would have cost them this one anyway.
Although Du Pont had tried to keep nylon a secret, word had spread through the textile industry, and several reporters had already guessed pretty closely what the company was up to by mid-1938. Also, the Du Pont Plastics Department had begun marketing nylon bristles, under the trademark Exton, in Dr. West's toothbrushes. This offered an attractive entering wedge in the marketplace for nylon; imperfect polymer produced in the pilot plant could be sold for toothbrush fibers. DuPont did not tell the public the chemical nature of its bristles.
Although the company was still more than a year and a half away from having stocking fiber to sell, the need to announce nylon arose because patents were beginning to issue and Du Pont officials were worried about losing control over nylon's publicity. Bolton suggested that Du Pont present a scientific paper at an American Chemical Society meeting. This was vetoed because a reputable scientific paper wouId have to include more information than the company wanted to divulge at this point. Because it had not explored all the process options, Du Pont worried that competitors or independent inventors could apply for nylon-related patents that could hinder the product's development.
So in October 1938 Stine made his announcement at the World's Fair site. The next day's New York Times ran two articles on nylon. One was entitled "New Hosiery Strong as Steel" and began "Coal, air, and water were revealed today...." The idea that supposedly indestructible stockings could be made from these ingredients seemed to many people a modern miracle. The phrase "coal, air, and water" became associated with nylon and the transforming magic of science. It was the new alchemy. Although Du Pont intentionally made very guarded statements about nylon, public interest remained high for the eighteen months before the first nationwide sales.
While work continued, sample stockings became available. As more and more comments came in, the outstanding feature of nylons appeared to be their durability. Plus they looked like silk. (Several hucksters even sold silk stockings as nylon at this time.) The fact that nylons felt cold and clammy did not dampen enthusiasm for them. Practicality and good looks seem to have outweighed comfort. Finally, nylons went on sale nationally in May 1940, and the demand was overwhelming. Convinced that nylon would prove superior to silk, Du Pont initially set its price 10 percent higher than that of silk.
In less than two years Du Pont captured more than 30 percent of the full-fashioned hosiery market. Then the United States' entry into World War II led to the diversion of all nylon into military uses. During the war Du Pont increased its nylon production threefold, to more than twenty-five million pounds a year; the biggest uses were for parachutes, airplane tire cords, and glider tow ropes. When the war ended and women began to demand nylons again, their demand greatly exceeded supply for two years. The shotage led to several riots by impatient women who had stood in line for hours for stockings. Newspapers ran stories with headlines such as "Women Risk Life and Limb in Bitter Battle over Nylons."
Nylon became far and away the biggest money-maker in the history of the Du Pont company, and its success proved so powerful that it soon led the company's executives to derive a new formula for growth. By putting more money into fundamental research, Du Pont would discover and develop "new nylons," that is, new proprietary products sold to industrial customers and having the growth potential of nylon. This faith seemed to be borne out in the late 1940s and early 1950s with the development of Orlon and Dacron and the continued spectacular growth of nylon. Du Pont had effected a revolution in textile fibers, and the revolution propeled earnings skyward.
In fact, Du Pont, which for its first hundred years had been an explosives manufacturer and had in this century become a diversified chemical company, was by the 1950s, in many respects, a fibers company that had some other businesses on the side.David A. Hounshell, a professor of history at the University of Delaware. is the author of From the American System to Mass Production, 1800 - 1932 (Johns Hopkins, 1984) and winner of the Society for the History of Technology's 1987 Dexter Prize. John K. Smith Jr. is assistant professor of history at Lehigh University. This article is adapted from their book Science and Corporate Strategy: Du Pont R&D, 1902-1980, (Cambridge University Press, 1998).
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