pa尼 龙（PA nylon）

pa尼 龙（PA nylon） pa尼 龙(PA nylon) Polyamide commonly known as Niron (Nylon), the English name Polyamide (referred to as PA), is the main chain containing repeated amide groups - [NHCO] - thermoplastic resin collectively. Including aliphatic PA, aliphatic aromatic PA and aromatic PA. Among them, aliphatic PA has many varieties and large yield, and is widely used. Its nomenclature is determined by the specific carbon number of the synthetic monomer. It was invented by Carlo Seth, a famous chemist in America and his research group. The main varieties of nylon of nylon 6 and nylon 66, absolute dominant position, followed by nylon 11, nylon 12, nylon 610, nylon 612 and nylon 1010, nylon 46, nylon 7, nylon 9, nylon 13, new varieties of nylon 6I, nylon 9T and nylon MXD6 (special barrier resins), nylon modified variety quantity, such as reinforced nylon, monomer casting nylon (MC nylon), reaction injection molding (RIM) aromatic nylon, nylon, nylon, high impact (Supertough nylon), electroplating conductive nylon, nylon, flame retardant nylon, nylon and other polymer blends and alloy, meet various special requirements, widely used in metal, wood and other traditional materials as substitutes for various structural materials. Nylon is the most important engineering plastic, and its output is the first in the five major engineering plastics. Nylon [1], a polyamide fiber (nylon), is a statement. It can be made into staple fiber or staple fiber. Nylon was developed by Carlo Seth, an outstanding scientist in the United States, and a research team under the leadership of Carothers, the first synthetic fiber in the world. The appearance of nylon gives a new look to the fabric, and its synthesis is a major breakthrough in the synthetic fiber industry. It is also an important milestone in polymer chemistry. In 1928, the DuPont Co, the largest chemical company in the United States, founded the Institute of basic chemistry, and Dr. Carlo Seth, 32, was employed as head of the institute. He is mainly engaged in the study of polymerization. He first studied polycondensation of bifunctional molecules, through esterification condensation diols and two carboxylic acids, the synthesis of polyester long chain, high relative molecular mass. In less than two years, Carlo Seth in the preparation of linear polymers especially polyester, has made important progress, will increase the molecular weight of polymer to 10000 to 25000, he put the relative molecular weight of more than 10000 polymers called polymers (Superpolymer). In 1930, Carlo Seth aides found two yuan, diols and carboxylic acids by condensation reaction from high polyester, the melt out of silk like cotton candy for that, and the fiber filaments even after cooling can continue to stretch, stretch length up to several times the original, after cooling after the tensile strength, elastic fiber, transparency and gloss are greatly increased. The strange properties of this polyester make them feel that they may have significant commercial value, and it is possible to spin fibers from molten polymers. However, further research has shown that fiber obtained from polyesters is of theoretical significance. Because high polyester melts at 100 degrees Celsius and is particularly soluble in various organic solvents, it is only slightly more stable in water and therefore unsuitable for use in textiles. Carlo Seth then made a thorough study of a range of polyesters and polyamides. After careful comparison, selected him for the first time in February 28, 1935 by hexamethylene diamine and adipic acid to synthesize polyamide 66 (the first 6 that the number of carbon atoms in two amine second 6 carbon atoms in the acid). The polyamide is not soluble in common solvents, melting point of 263 DEG C, higher than the ironing temperature usually used, drawn fiber of silk appearance and gloss on the structure and properties are close to natural silk, its strength and abrasion resistance is better than that of any kind of fiber. Considering its nature and manufacturing cost, it is the best choice in the known polyamides. Then, the DuPont Co to solve the industrial sources of raw material production of polyamide 66, October 27, 1938 officially announced the world's first synthetic fiber was born, and this named polyamide 66 synthetic fiber nylon (Nylon). Nylon was later made in English as a general term for all polyamides from coal, air, water, or other substances, with abrasion resistance and flexibility, and a chemical structure similar to that of proteins". Polyamide (nylon) Poly sebacic acid sebacic two amine (nylon 1010) Poly eleven amide (nylon 11) Poly twelve amide (nylon 12) Poly (caprolactam 6) Poly (sebacic two) ethylenediamine (nylon 610) Poly twelve alkyl two ethylenediamine (nylon 612) Polyhexamethylene adipamide (nylon 66) CAS encoding: 32131-17-2 Polyamide (nylon 8) Poly 9- amino acid (nylon 9) Nylon 6 and nylon 66 * structure: Nylon 6 nylon, nylon 66 and poly hexamethylene diamine adipate. Nylon 66 is 12% harder than nylon 6, and in theory, the higher the hardness, the greater the brittleness of the fiber, and the more likely it is to break. But in carpet use, this tiny difference can not be separated. * cleaning and antifouling: these two properties are the cross-sectional shape of the fiber and the antifouling treatment of the rear rail. The strength and hardness of the fiber itself have little influence on the cleaning and antifouling properties. * melting point and elasticity: Nylon 6 has a melting point of 220C, while nylon 66 has a melting point of 260C. But this is not a difference in terms of carpet use and temperature conditions. The lower melting point makes nylon 6 have better resilience, fatigue resistance and thermal stability as compared with nylon 66. Colour fastness: color fastness is not a characteristic of nylon. It is the dye in nylon, not the nylon itself, that fades in the light. * abrasion resistance and dust resistance: Clemson University in the United States at Tampa International Airport, respectively, with BASF Zeftron500 nylon 6 carpet and DuPont Antron XL nylon 66 carpet for a two and a half years of experiments. The carpet in the high flow of people under the condition, the results showed that BASF Zeftron500 nylon retaining and pile wear resistance is better than the DuPont Antron XL in color. There is no difference in dust resistance between the two yarns. Modification of nylon Because nylon has many characteristics, it is widely used in automobile, electrical equipment, machinery department, transportation equipment, textile, paper making machinery and so on. With the miniaturization of automobiles, the high performance of electronic and electrical equipment and the acceleration of mechanical equipment, the demand for nylon will be higher. In particular, nylon as a structural material, its strength, heat resistance, cold resistance and other aspects of a high demand. An important factor is the inherent disadvantage of nylon limited its application, especially for PA6, PA66 two varieties, PA46, PAl2 and other varieties than has a strong price advantage, although some performance can not meet the requirements of the development of related industries. Therefore, it is necessary to expand the field of application for an application area by modifying and improving its performance. Mainly in the following aspects of modification. Improve the water absorption of nylon and improve the dimensional stability of nylon. Improving the flame retardancy of nylon to meet the requirements of electronics, electrical and communication industries. Improve the mechanical strength of nylon in order to reach the strength of metal material instead of metal Improving the low temperature resistance of nylon and enhancing its resistance to environmental strain. Improve the abrasion resistance of nylon so as to meet the requirement of high wear resistance. To improve the antistatic property of nylon, in order to meet the application requirements of mine machinery and. The improvement of heat resistance of nylon, such as automobile engine to adapt to high temperature field conditions. The lower the cost and improve the competitiveness of products of nylon. In conclusion, through the above improvement, the nylon composite can be highly functional and functional, so as to promote the development of related products to high performance and high quality. Recent developments in modified PA products As mentioned earlier, glass fiber reinforced PA there in 1950s, but the formation of industrialization is 1970s, since 1976 the United States DuPont Co develop new tough PA66, many large companies have developed new modified PA product, the United States, Western Europe, Japan, Holland, Italy and other developing enhanced PA, PA, PA flame retardant filling, change a lot of PA market. In 1980s, the success of compatible agent technology development, promote the development of PA alloy, countries around the world have developed PA / PE, PA / PP, PA / ABS, PA / PC, PA / PBT, PA / PET, PA / PPO, PA / PPS, PA / I.CP (liquid crystal polymer), PA / PA etc. thousands of kinds of alloy, widely used in automobile, motorcycle, electronics, electrical machinery, textiles, sports goods, office supplies, household appliances parts industry. In 1990s, new varieties of modified nylon is increasing, this period of modified nylon towards commercialization, the formation of a new industry, and has been developing rapidly, at the end of 1990s, the world's nylon alloy production reached 1 million 100 thousand tons / year. In product development, mainly in high performance nylon PPO / PA6, PPS / PA66, toughened nylon, nano nylon, halogen-free flame retardant nylon as the leading direction; in the aspect of application, automobile parts, electrical parts development has made significant progress, such as the modification of nylon has been commercialized high flow for automotive air intake manifold, this kind of complex structure the plastic parts, besides is of great significance in the application, more important is to prolong the life of components, promote the development of processing technology of Engineering plastics. Trends in the development of modified nylon Nylon engineering plastics as the largest and most important varieties, has very strong vitality, mainly because it is modified to achieve high performance, followed by cars, electrical appliances, communications, electronics, machinery and other industries of high performance products are more strongly. The rapid development of related industries, promote high performance engineering the process of plastic, nylon future development trend are as follows. The market demand and the high strength and high rigidity nylon larger reinforced materials such as inorganic whisker and carbon fiber reinforced PA will become an important new varieties, mainly used in automotive engine parts, mechanical parts and components of Aeronautical equipment. Nylon alloy will become the mainstream of the development of modified engineering plastics. Nylon alloying is an important way to achieve high performance of nylon. It is also the main means of making nylon special material and improving the performance of nylon. By mixing other polymers, the water absorption of nylon can be improved, the dimensional stability of the products can be improved, and the brittleness, heat resistance and wear resistance of nylon can be improved. Therefore, the utility model is suitable for different requirements of the vehicle. The manufacturing technology and application of nano nylon will be developed rapidly. The advantage of nano nylon is that its thermal properties, mechanical properties, flame retardance and barrier properties are higher than pure nylon, and its manufacturing cost is equivalent to that of nylon. Therefore, it is very competitive. The flame retardant nylon for electronic, electrical and electrical appliances is increasing day by day, and green flame retardant nylon is paid more and more attention by the market. Antistatic, conductive nylon and magnetic nylon will be the preferred materials for electronic equipment, mining machinery and textile machinery. Research and application of the processing aids, will promote the function and modification of Nylon high performance process. The application of the integrated technology, the fine product is the impetus of the development of the industry. Polyamide fiber is a general term for C9-NH fibers on the macromolecular chain. Commonly used for aliphatic polyester amine, the main varieties are polyamide 6 and polyamide 66, China's goods are nylon 6 and nylon 66. Nylon fiber is mainly made of filament and a small amount of staple fiber, mainly used for blending with cotton, wool or other chemical fiber. Nylon filaments are widely used in texturing to produce stretch yarns as woven or knitted materials. Nylon fiber is usually spun by melt spinning. The strength of nylon 6 and nylon 66 fiber is 4 ~ 5.3cN / dtex, the high strength polyester can reach 7.9cN / dtex, the elongation is 18% ~ 45%, and the elastic recovery rate is more than 90% at 10% elongation. It is determined that the abrasion resistance of nylon fiber is 20 times of cotton fiber, 20 times of wool and 50 times of viscose. Fatigue resistance ranks first among all kinds of fibers. In civil use, a large number of socks and other blended products are used to improve the abrasion fastness of fabrics, but the nylon fiber has low modulus and crease resistance, which restricts the application of nylon in the clothing field. Nylon cord life is 3 times bigger than viscose, impact absorption energy, so the tire can travel on a bad road, but because the nylon cord elongation, the car is stopped, the tire deformation of flat point, starting early auto beating. Therefore, it can only be used for the tyres of freight cars, and is not suitable for the tire cord of passenger cars. The surface of the polyamide fiber is smooth, and the friction coefficient of the non oiling agent is very high, Nylon oil is easy to be lost in storage, and it needs to be added with oil during textile processing. The polyamide fiber absorbent than polyester, nylon 6 and nylon 66 under standard conditions of moisture regain is 4.5%, second only to PVA in synthetic fibers. Good dyeing property. Acid dyes, disperse dyes and other dyes can be used. History of nylon: People are no strangers to nylon. In daily life, nylon products are everywhere, but few people know about it. Nylon is one of the first synthetic fibers developed in the world. In the early twentieth Century, it was considered an unthinkable thing to engage in basic scientific research in the business world. In 1926, the DuPont Co, the largest industrial company in the United States, was interested in basic science and suggested that the company carry out basic research on the discovery of new scientific facts. In 1927 the company decided to pay $250 thousand a year as the research cost, and began to employ chemical researchers to study chemical based DuPont Co established in 1928, the 32 year old Carlo Seth (Wallace H. Carothers, 1896 ~ 1937), hired as head of the Department of organic chemistry. Carlo Seth, American organic chemist. Born in April 27, 1896 in Iowa, Wilmington. In April 29, 1937, he died in Philadelphia, USA. After receiving his Ph. D. from University of Illinois in 1924, he worked as an organic chemistry professor in the University and Harvard University. In 1928, he applied for organic chemistry research at the DuPont Co laboratory in Wilmington, USA. He presided over a series of studies on the use of polymeric methods to obtain high molecular weight substances. In 1935 prepared polymers with adipic acid and hexanediamine, due to containing 6 atoms of carbon in the two fractions, then known as the 66 polymer. He then melts the polymer and passes it through the needle, which is called a fiber in tension. This fiber, that is, polyamide 66 fiber, was industrialized in 1939. It is called Nylon. It is the earliest synthetic fiber variety to realize industrialization. The synthesis of nylon laid the foundation of the synthetic fiber industry, and the appearance of nylon made the textile look brand-new. Fabric made of this fiber nylon stockings is transparent and durable than silk stockings, 10 1939 24, DuPont public eye caused a sensation in the headquarters of public sale of nylon stockings, regarded as precious to panic buying, people have used "as thin as silk, as steel, like silk silk beauty" the words of praise to the fiber, nylon fabric to May 1940 sales throughout the United states. From the outbreak of the Second World War until 1945, the nylon industry was diverted to parachute, aircraft, tires, cord fabrics, military uniforms and other military products. Because of the characteristics of nylon and a wide range of uses, after the second world war is developing very rapidly, a variety of products from nylon stockings, dress to the carpet, fishing nets, in countless ways, is one of the three synthetic fiber. A hot balloon made of nylon can be done a great deal Nylon (English Nylon) is an artificial polymer. In February 28, 1935, Wallace Carothers of the DuPont Co invented this kind of plastic in Wilmington. Nylon officially listed in 1938, The earliest nylon products were nylon toothbrushes, brushes (sold in February 24, 1938) and nylon stockings for women (listed in May 15, 1940). Today nylon fiber is the raw material for a variety of synthetic fibers. Hard nylon is used in the construction industry. structure Chemically, nylon is a condensation polymer, whose units are linked by amides, so it is sometimes called polyamides. Nylon is the first fully synthetic fiber in the world, with raw materials such as coal, water and air. Two basic chemicals are generally synthesized from these raw materials, and in most cases six methylene, two amines, and adipic acid. They are mixed together to form nylon. Nylon 6,6 The most common is nylon 6,6 or nylon 66, which means six methylene, two amines, and adipic acid contain six carbon atoms. In the chain of polymers, six methylene two amines and adipic acid alternate with each other, so unlike other polymers (e.g. proteins), the directions of amides in nylon change constantly. History The origin of the word nylon is not very clear. Many people say it is made up of NY (New York, English, New, York) and Lon (London, English, London). These two places are the first places to make nylon. But this statement is groundless. In 1940, DuPont Co said that Nyl was found at random, and on was because the English word for many fibres (such as cotton, English, Cotton) ended in on. In an article published by DuPont in 1978, they said they were going to call it No-Run, but later to make it look good, it changed to Nylon, nylon. Another popular legend is that nylon is the abbreviation of Now, You, Lazy, Old, Nippon. In the background, in 1930s, a lot of cheap Japanese textiles hit western society. Nylon is therefore considered a competitive product for Japanese textiles. Although the word "nylon" is very popular, it has never been used as a trademark or under the protection of a trademark. During the Second World War, allied forces used nylon parachutes (usually made from Asian silk), and other military materials, such as tires, tents and ropes, were also made from nylon. It is even used to make paper for printing American currency. At the beginning of the war, cotton accounted for 80% of the fiber, and 20% of the others were mainly wood fibers. In August 1945 cotton was reduced to 75%, while the proportion of man-made fibres rose to 25%. Characteristic 1. DuPont Tactel nylon fabric soft and comfortable, and its good moisture absorption can balance the air and humidity difference between the body, thereby reducing the pressure on the body, with the adjustment effect. 2. special lightweight, easy maintenance. 3. machine washable, dry time is three times faster than cotton, or simply micro hot press, not easy to deformation, has significant anti wrinkle ability. 4. because of its outstanding resilience, it can be restored to its original state after stretching. Modification of nylon Because of the strong polarity of PA, it has strong hygroscopicity and poor dimensional stability, but it can be improved by modification. Glass fiber reinforced PA Add 30% glass fiber to the PA, The mechanical properties, dimensional stability, heat resistance and aging resistance of PA were obviously improved, and the fatigue strength was not increased by 2.5 times. The forming process of glass fiber reinforced PA is approximately the same as that without strengthening, but the injection pressure and injection speed should be increased properly, and the barrel temperature can be increased by 10-40 degrees. The glass will be oriented along the flow direction in the injection process, caused by the mechanical properties and shrinkage rate enhancement in the direction of orientation, leading to deformation of product warpage, therefore, mold design, location and shape of the gate should be reasonable, the process can improve the temperature of the die, after removing the products into hot water to slow cooling. In addition, the larger the proportion of glass fiber, the greater the wear of the plastic parts of the injection molding machine, it is better to use double metal screw, cylinder. Flame retardant PA Because PA added a flame retardant, most flame retardant under high temperature decomposition, releasing acidic substances, corrosive to metal, therefore, plasticizing components (screw, plastic head, rubber ring, rubber gasket, flange etc.) to hard chrome plating. Process, as far as possible to control the cylinder temperature can not be too high, the injection speed can not be too fast, in order to avoid excessive temperature due to decomposition of rubber, causing products to change color and mechanical properties. Transparent PA Have good tensile strength, impact strength, rigidity, abrasion resistance, chemical resistance, surface hardness, high transmittance, similar to optical glass, processing temperature of 300--315, when processing, the need to strictly control the barrel temperature, the melt temperature is too high will change due to degradation products, the temperature is too low due to poor plasticizing affect the transparency of products. Mold temperature as low as possible, mold temperature is high, due to crystallization and reduce the transparency of products. Weatherproof PA In PA, carbon black and other ultraviolet absorption additives are added. These self lubrication of PA and wear of metal are greatly enhanced, and the blanking and wearing parts will be affected during forming process. Therefore, the need to use strong feed capacity and high wear resistance of the screw, machine cylinder, rubber head, rubber ring, rubber gasket combination. Polyamide Polyamide (PA, commonly known as nylon) is the United States DuPont company's first development of resins for fiber, in 1939 to achieve industrialization. In 1950s, it began to develop and produce injection molding products to replace metal and meet the requirements of lightweight and lower cost of downstream industrial products. Contains many repeated amide and polyamide backbone, used as a plastic called nylon, synthetic fiber as we called nylon, polyamide can be prepared from two yuan amine and acid, can be synthesized by Omega amino acid or lactam ring. According to the number of carbon atoms containing two yuan amine and dibasic acid or amino acids, can be prepared a variety of polyamide, polyamide currently up to dozens of varieties with application of polyamide -6, polyamide -66 and polyamide -610 most widely. The link structures of polyamide -6, polyamide -66 and polyamide -610 are [NH (CH2), [NH (CH2), 6NHCO (CH2), 4CO] and [NH (CH2), 6NHCO (CH2), 8CO], 5CO], respectively. Polyamide -6 and polyamide -66 are mainly used in spinning synthetic fibers, called nylon -6 and polyamide -66. Nylon -610 is a kind of thermoplastic engineering plastics with excellent mechanical properties. PA has good comprehensive properties, including mechanical properties, heat resistance, abrasion resistance, chemical resistance and self lubrication, low friction coefficient, flame retardancy, some easy processing, suitable for filling reinforced with glass fiber and other fillers, improve the performance and expand the scope of application. There are many varieties of PA, such as PA6, PA66, PAll, PAl2, PA46, PA610, PA612, PAl010 and so on, and many new varieties of semi aromatic nylon PA6T and special nylon developed in recent years. -6 nylon plastic products can be made of metal sodium and sodium hydroxide as catalyst, N- acetyl caprolactam as cocatalyst, the delta caprolactam directly in the model by anionic ring opening polymerization system, called casting nylon. This method facilitates the manufacture of large plastic parts. Mainly used in the synthesis of polyamide fiber, its most outstanding advantage is higher than all the other wear resistance is 10 times higher than the cotton fiber, wear resistance, 20 times higher than in the wool blended fabric slightly adding polyamide fiber, can greatly improve the wear resistance; when stretched to 3-6%, elastic recovery rate can up to 100%; through tens of thousands of times the folding deflection without rupture. The strength of polyamide fiber is 1-2 times higher than that of cotton, 4-5 times higher than wool, and 3 times of viscose fiber. But the polyamide fiber, heat resistance and light resistance is poor, also to maintain the poor clothes made of polyester as crisp. In addition, for clothing and nylon -66 nylon -6 has hygroscopicity and dyeing the shortcomings of the poor, for the development of new varieties of polyamide fiber polyamide fiber, nylon -3 and nylon -4, with light weight, good wrinkle resistance and good air permeability and good durability, dyeing and heat setting etc. Therefore, is considered to be very promising. The polyamide is non-toxic, light weight, good mechanical strength, wear resistance and good corrosion resistance, so it is widely used in place of copper and other metals in mechanical, chemical, instrumentation, automotive and other industries manufacturing bearings, gear, pump and other parts. Melt spun polyamide has very high strength, mainly synthetic fibers and can be used as medical suture. Nylon can be blended or made into a variety of medical and knitted fabrics for civilian use. Many nylon filament used for knitting and weaving silk industry, silk stockings, stockings and other single elastic interpretation of the various kinds of wear nylon stockings, nylon nets, nylon gauze, lace, stretch nylon coat, all kinds of nylon silk or silk woven products. Nylon staple fibers are mostly blended with wool or other chemical fiber wool products to make all kinds of wear resistant materials. In industry, nylon is used to make cords, industrial fabrics, ropes, belts, tents, fishing nets and so on. Used primarily as a parachute and other military fabric in national defence. A repetitive structure on the molecular chain of polyamides; a class of polymers that are not amide groups. Special nylon fiber Nano nylon According to Japan's Dongli chemical company news, the company has successfully developed a very fine fiber diameter than ever smaller two digit nano filament structure "nano fiber" of new technology, the control technology has reached the limit of nano structure of fiber fineness. Dongli Chemical Co., ltd., Using the new technology, the company has developed a nylon fiber consisting of more than 1 million 400 thousand monofilament with a diameter of 10 m. Compared with previous products, this kind of fiber has about 1000 times the surface area of the past and has high surface activity. Super nylon fiber Triangle - Raleigh nylon fiber has many uses, from clothing, carpet to rope to microcomputer data lines, can use this kind of fiber. Now researchers at the University of North Carolina's textile institute are working to improve the fiber, which has been reported to have produced the strongest aliphatic nylon fibers. The scientist Dr. Tonari - Professor of polymer chemistry and textile engineering, assistant professor of natural science Dr. Richard. Cuttack is working on a way in the complex process of the case does not require expensive costs, and produce higher emphasis on nylon fiber. They used aliphatic nylon or nylon to study the carbon assistance of nylon, using straight chains or open branched chains, which used to emphasize the absence of large chains. Stronger aliphatic nylon can be applied to ropes, handling belts, parachutes and car tires, or producing synthetic materials that are suitable for high temperature applications. The discovery was recently presented at the annual meeting of the American Chemical Sciences Conference in Philadelphia and appeared in the journal polymer science. The fibers are made from polymers or long chain molecules including many units. When these polymer chains are arranged neatly, the polymer will become crystalline. These coiled polymers need to be stretched, and if they are to make stronger fibers, they need to be removed from their elasticity. Adding hydrogen to the nylon chain prevents stretching, so overcoming this combination is a key factor in producing stronger nylon fibers. Super fiber, Yikaifulaer fiber as an example, from aromatic nylon polymer produced is stiff, long chain consists of chain, aromatic nylon is very difficult, so it is very expensive. So Professor Tonari and Dr Ktak studied polyamide 66 (nylon 66), a commercially thermoplastic material that is easy to make, but difficult to stretch and arrange. It is also difficult to remove nylon 66 elasticity. The discovery could solve the problem that nylon 66 could dissolve in three gallium chloride, effectively breaking the hydrogen bonding problem. Allow polymer chain extension. Professor Tonari says the new fiber may be 10 times more expensive than typical aliphatic nylon. The production of aliphatic nylon is very economical and feasible. High stress fibers such as Kevlar fiber must be produced in the professional factory, this is because in the production process for concentrated sulfuric acid. The new fibers can be made from plain spinning fiber units, and there is no particular place in the process. Dr Tonari and Dr Ktak continue their research. It is not known whether hydrogen bonding and the effect on nylon 66 fiber will occur.