People are no strangers to nylon. Nylon products abound in everyday life, but few people know its history. Nylon is a synthetic fiber first developed in the world.

At the beginning of this century, the basic scientific research in the corporate world was considered an incredible thing. In 1926, Charles M.a.Stine (1882-1954), the director of DuPont, the largest industrial company in the United States, suggested that the company conduct basic research on discovering new scientific facts because of its interest in basic science. In 1927, the company decided to pay $250,000 a year for research and began hiring chemical researchers. By 1928, DuPont established the Institute of Basic Chemistry at its headquarters in Wilmington, Delaware, at the age of 32. Dr. Caraces (Wallace H. Carothers, 1896-1937) was hired as the head of all the machine chemistry departments.

Carothers was born on April 27, 1896 in Burlington, Loire, USA. He began his education at the Des Moines Public School and graduated from North Middle School in 1914. Carothers's father taught at the Des Moines School of Business and later served as the vice president of the institute. Influenced by his father, Carothers entered the college to study accounting when he was 18 years old. He is not interested in this major, but he likes natural sciences such as chemistry. Therefore, he transferred to a smaller college a year later. Chemistry. Bachelor of Science in 1920. In 1921, he obtained a master's degree from the University of Illinois, and later taught at the University of Kota in the south, teaching analytical chemistry and physical chemistry. In 1023, he returned to the University of Illinois to pursue a Ph.D. in organic chemistry. Under the guidance of the instructor Rogeradams (1889-1971), the paper on the catalytic hydrogenation of platinum black was completed, which revealed his talents and immediately stayed in school after receiving his Ph.D. In 1926, he taught organic chemistry at Harvard University. Because Carothers is introverted, he believes that scientific research can more exert his ingenuity, so he was hired to DuPont in 1928.

When Carothers came to DuPont, it was a fierce debate on the polymer theory proposed by German organic chemist Hermann Staudinger (1881 ~ 1965). Carothers praised and supported Tao Dingge’s point of view is determined by experiments to confirm the correctness of this theory. Therefore, he regards the exploration of polymers as the main research direction of the Department of Organic Chemistry. At first, Carothers chose the reaction of diols with dicarboxylic acids, and wanted to understand the relationship between the structure of organic molecules and their properties through this well-known reaction. In the experiment in which the polycondensation reaction was carried out, a polyester molecule having a molecular weight of about 5,000 was obtained. In order to further increase the degree of polymerization, Carothers improved the high vacuum distiller and strictly controlled the ratio of the reaction, so that the reaction proceeded completely, and the molecular weight of the polymer reached 10,000 to 20,000 in less than two years.

In 1930, Carothers condensed polyester with ethylene glycol and sebacic acid. In the experiment, Carolus colleague Hill discovered an interesting phenomenon when removing molten polyester from the reactor: The molten polymer can be drawn out like marshmallow, and the fibrous filament can continue to be stretched even after cooling, the stretching length can be several times, the strength of the fiber after cold drawing and The elasticity is greatly increased. This phenomenon, which has never been seen before, makes them predict that this property may have significant application value, and it is possible to use a molten polymer to spin the fiber. They then conducted in-depth research on a range of polyester compounds. Since the polyesters studied at that time were polymers of fatty acids and fatty alcohols, which had the disadvantages of easy hydrolysis, low melting point (<100 ° C), and easy to dissolve in organic solvents, Carothers concluded that polyester does not have a system. Taking the wrong conclusion of synthetic fiber, the research on polyester was finally abandoned. By the way, just after Carrousus gave up the research, the UK's Winfield TRWhinfield, 1901-1966), based on the results of these studies, switched to aromatic carboxylic acids (terephthalic acid) and The diol was polycondensed and the polyester fiber-polyester was synthesized in 1940. This is a pity for Carothers.

In order to synthesize high-performance polymers with high melting point, Carothers and his colleagues turned their attention to the polycondensation reaction of diamines and dicarboxylic acids. In a few years, Carothers and him Colleagues have prepared a variety of polyamides from different polymerizations of diamines and dibasic acids, but the properties of this material are not ideal. At the beginning of 1935, Carothers decided to synthesize polyamide (ie, polyamide 510) with pentamethylenediamine and sebacic acid. The experimental results show that the fiber drawn from this polyamide has stronger strength and elasticity than silk, and is not easy to absorb water. Insoluble, the disadvantage is that the melting point is low, the raw materials used are very expensive, and it is not suitable for commodity production. Immediately after Carlos chose hexamethylenediamine and adipic acid for polycondensation, polyamide 66 was finally synthesized on February 28, 1935. This polymer is insoluble in common solvents and has a high melting point of 263 ° C. Due to its structure and properties closer to natural silk, the drawn fiber has a silk appearance and gloss, and its abrasion resistance and strength exceed those of any fiber at that time. And the price of raw materials is also relatively cheap, DuPont decided to develop the production of goods.

It is necessary to turn the results of the laboratory into commodities, first to solve the industrial source of raw materials; second, to develop the production technology and equipment for transportation, metering and winding in the melt spinning process. The raw materials required for the production of polyamide 66 - adipic acid and hexamethylene diamine were only used as reagents in the laboratory at that time. It was necessary to develop and produce large quantities and suitable adipic acid and hexamethylene diamine. DuPont chose a rich phenol for development experiments. By 1936, a chemical plant in West Virginia used a new catalytic technology to produce adipic acid in large quantities with cheap phenol, and then invented a new process for producing hexamethylene diamine from adipic acid. DuPont pioneered a new technology of melt silk spinning, which melted and melted polyphenolamine 66, filtered and then sucked into the pump, sprayed into filaments through key components (spinning head), and the sprayed filaments were cooled by air. Stretching and shaping. The pilot test was completed in July 1938, and the first production of polyamide fiber. The toothbrush with polyamide 66 as the toothbrush was launched on the market in the same month. On October 27th, DuPont officially announced that the world's first synthetic fiber was officially born, and the polyphenolamine 66 synthetic fiber was named nylon (nylon), which later became a polyamide synthetic fiber in English. The name of the unified product. DuPont started the basic research of high polymer for 11 years and spent 22 million US dollars. 230 experts participated in the work and finally realized industrial production at the end of 1939. Unfortunately, the inventor of Niyou, Carothers, could not see the practical application of nylon. Because Carothers has always been depressed, there is a thought that prevents him from getting rid of. He always thinks that being a scientist himself is a loser. In addition, his favorite twin sister died in 1936, which made his mood even heavier. A chemist who made an outstanding contribution in the field of chemistry committed suicide by drinking lemon juice mixed with potassium cyanide in a room in a hotel in Philadelphia, USA on April 29, 1937. To commemorate the achievements of Carothers, in 1946 DuPont renamed the nylon research laboratory at the Umilh factory to the Carothers laboratory.

The synthesis of nylon has laid the foundation for the synthetic fiber industry, and the advent of nylon has given the textile a new look. The nylon stockings woven with this kind of fiber are both transparent and more durable than the stockings. In 1939, on the 24th, DuPont caused a sensation when selling nylon stockings at the headquarters. It was regarded as a rare thing to rush to buy, chaotic situation. Forced the security organs to dispatch police to maintain order. People have praised this fiber with the words "small as a gossamer, as strong as a wire, as beautiful as a silk." By May 1940, nylon fiber fabrics were sold throughout the United States. From the outbreak of the Second World War until 1945, the nylon industry was turned into military products such as parachutes, aircraft tire cords, and military uniforms. Due to the nature of nylon and its wide range of uses, it developed very rapidly after World War II. Nylon's products range from stockings, clothing to carpets, fishing nets, etc., in an uncountable manner. In the first decade, the output increased by 25 times. In 1964, it accounted for more than half of the synthetic fiber. Although the total output of polyamide fiber is not as good as that of polyester fiber, it is still one of the three synthetic fibers.

The invention of nylon began with basic research without a clear application purpose, but eventually led to the creation of Niu products that changed people's lives, and became a very successful example of the basic scientific research of the company. It makes people realize that science is ahead of technology, and technology is ahead of production; without scientific research, without technological achievements, the development of new products is impossible. Since then, basic research conducted or funded by companies has sprung up around the world, enabling the results of basic research to be more rapidly transformed into productivity.

The synthesis of nylon is an important milestone in the development of polymer chemistry. Before DuPont conducted this research, the international debate on the theory of polymer chain structure was mainly due to the lack of clear and unquestioned experimental facts. At the time, the polycondensation reaction was rarely studied, and the obtained polycondensate was not perfect. Carothers adopts a method far exceeding the general procedure for organic synthesis. When the polymer polycondensation reaction is carried out, the ratio of the reactants is very strict, and the difference is not more than 1%. The degree of polycondensation reaction is quite thorough, exceeding 99.5%, thereby synthesizing a polymer having a molecular weight of up to about 20,000. The study by Carothers shows that the polymer is a true macromolecule, which can be obtained by a known organic reaction, and each molecule of the polycondensation reaction contains one or two or more reactive groups, and these groups The cohesion of the polycondensation reaction is revealed by interconnecting the covalent bonds, rather than simply bringing together small molecules by an indeterminate force. By studying the polymerization reaction, Carothers roughly divides the polymer compounds into two categories: one is a condensation polymer obtained by polycondensation reaction; the other is an addition polymer obtained by addition polymerization. Carolus's assistant, Paul J. Flory (1910-1986), summarized a series of polycondensation reactions such as polyamide. In 1939, the basic principle that all functional groups in the polycondensation reaction have the same activity was proposed, and the polycondensation was proposed. The quantitative relationship between reaction kinetics and molecular weight and degree of polycondensation reaction. Later, the statistical mechanics of polymer solutions and the statistical mechanics of polymer models and conformations were studied. In 1974, the Nobel Prize in Chemistry was won. The synthesis of nylon strongly proves the existence of polymers, which makes people believe in the theory of Staudinger. From then on, polymer chemistry is really established.

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