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P-Phenylenediamine
''p''-Phenylenediamine (PPD) is an organic compound with the formula C6H4(NH2)2. This derivative of aniline is a white solid, but samples can darken due to air oxidation. It is mainly used as a component of engineering polymers and composites like kevlar. It is also an ingredient in hair dyes and is occasionally used as a substitute for henna. Production PPD is produced via three routes. Most commonly, 4-nitrochlorobenzene is treated with ammonia and the resulting 4-nitroaniline is then hydrogenated: :ClC6H4NO2 + 2 NH3 → H2NC6H4NO2 + NH4Cl :H2NC6H4NO2 + 3 H2 → H2NC6H4NH2 + 2 H2O In the DuPont route, aniline is converted to diphenyltriazine, which is then converted by acid-catalysis to 4-aminoazobenzene. Hydrogenation of the latter affords PPD.Robert A. Smiley "Phenylene- and Toluenediamines" in ''Ullmann's Encyclopedia of Industrial Chemistry'', 2002, Wiley-VCH, Weinheim. Uses Precursor to polymers PPD is a precursor to aramid plastics and fibers such as ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hair Dye
Hair coloring, or hair dyeing, is the practice of changing the hair color. The main reasons for this are cosmetic: to cover gray or white hair, to change to a color regarded as more fashionable or desirable, or to restore the original hair color after it has been discolored by hairdressing processes or sun bleaching. Hair coloring can be done professionally by a hairdresser or independently at home. Today, hair coloring is very popular, with 75% of women and 18% of men living in Copenhagen having reported using hair dye (according to a study by the University of Copenhagen). At-home coloring in the United States reached $1.9 billion in 2011 and was expected to rise to $2.2 billion by 2016. History Diodorus Siculus, a Greek historian, described in detail how Celtic people dyed their hair blonde: "Their aspect is terrifying... They are very tall in stature, with rippling muscles under clear white skin. Their hair is blond, but not naturally so: they bleach it, to this day, artifi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aramid
Aramid fibers, short for aromatic polyamide, are a class of heat-resistant and strong synthetic fibers. They are used in aerospace and military applications, for ballistic-rated body armor fabric and ballistic composites, in marine cordage, marine hull reinforcement, and as an asbestos substitute. The chain molecules in the fibers are highly oriented along the fiber axis. As a result, a higher proportion of the chemical bond contributes more to fiber strength than in many other synthetic fibers. Aramids have a very high melting point (>500 °C). Common aramid brand names include Kevlar, Nomex, and Twaron. Terminology and chemical structure ''Aramid'' is a shortened form of aromatic polyamide. The term was introduced in 1972, accepted in 1974 by the Federal Trade Commission of the USA as the name of a generic category of fiber distinct from nylon, and adopted by the International Standards Organisation in 1977. Aromatic in the name refers to the presence of aromatic rings ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kevlar
Kevlar (para-aramid) is a strong, heat-resistant synthetic fiber, related to other aramids such as Nomex and Technora. Developed by Stephanie Kwolek at DuPont in 1965, the high-strength material was first used commercially in the early 1970s as a replacement for steel in racing tires. It is typically spun into ropes or fabric sheets that can be used as such, or as an ingredient in composite material components. Kevlar has many applications, ranging from bicycle tires and racing sails to bulletproof vests, all due to its high tensile strength-to-weight ratio; by this measure it is five times stronger than steel. It is also used to make modern marching drumheads that withstand high impact; and for mooring lines and other underwater applications. A similar fiber called Twaron with the same chemical structure was developed by Akzo in the 1970s; commercial production started in 1986, and Twaron is now manufactured by Teijin. History Poly-paraphenylene terephthalamide (K2 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hair Coloring
Hair coloring, or hair dyeing, is the practice of changing the hair color. The main reasons for this are cosmetic: to cover gray or white hair, to change to a color regarded as more fashionable or desirable, or to restore the original hair color after it has been discolored by hairdressing processes or sun bleaching. Hair coloring can be done professionally by a hairdresser or independently at home. Today, hair coloring is very popular, with 75% of women and 18% of men living in Copenhagen having reported using hair dye (according to a study by the University of Copenhagen). At-home coloring in the United States reached $1.9 billion in 2011 and was expected to rise to $2.2 billion by 2016. History Diodorus Siculus, a Greek historian, described in detail how Celtic people dyed their hair blonde: "Their aspect is terrifying... They are very tall in stature, with rippling muscles under clear white skin. Their hair is blond, but not naturally so: they bleach it, to this day, artifi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kevlar
Kevlar (para-aramid) is a strong, heat-resistant synthetic fiber, related to other aramids such as Nomex and Technora. Developed by Stephanie Kwolek at DuPont in 1965, the high-strength material was first used commercially in the early 1970s as a replacement for steel in racing tires. It is typically spun into ropes or fabric sheets that can be used as such, or as an ingredient in composite material components. Kevlar has many applications, ranging from bicycle tires and racing sails to bulletproof vests, all due to its high tensile strength-to-weight ratio; by this measure it is five times stronger than steel. It is also used to make modern marching drumheads that withstand high impact; and for mooring lines and other underwater applications. A similar fiber called Twaron with the same chemical structure was developed by Akzo in the 1970s; commercial production started in 1986, and Twaron is now manufactured by Teijin. History Poly-paraphenylene terephthalamide (K2 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kevlar Chemical Structure H-bonds
Kevlar (para-aramid) is a strong, heat-resistant synthetic fiber, related to other aramids such as Nomex and Technora. Developed by Stephanie Kwolek at DuPont in 1965, the high-strength material was first used commercially in the early 1970s as a replacement for steel in racing tires. It is typically spun into ropes or fabric sheets that can be used as such, or as an ingredient in composite material components. Kevlar has many applications, ranging from bicycle tires and racing sails to bulletproof vests, all due to its high tensile strength-to-weight ratio; by this measure it is five times stronger than steel. It is also used to make modern marching drumheads that withstand high impact; and for mooring lines and other underwater applications. A similar fiber called Twaron with the same chemical structure was developed by Akzo in the 1970s; commercial production started in 1986, and Twaron is now manufactured by Teijin. History Poly-paraphenylene terephthalamide (K29) â ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
4-nitroaniline
4-Nitroaniline, p-nitroaniline or 1-amino-4-nitrobenzene is an organic compound with the formula C6H6N2O2. A yellow solid, it is one of three isomers of nitroaniline. It is an intermediate in the production of dyes, antioxidants, pharmaceuticals, gasoline, gum inhibitors, poultry medicines, and as a corrosion inhibitor. Synthesis 4-Nitroaniline is produced industrially via the amination of 4-nitrochlorobenzene: :ClC6H4NO2 + 2 NH3 → H2NC6H4NO2 + NH4Cl Below is a laboratory synthesis of 4-nitroaniline from aniline. The key step in this reaction sequence is an electrophilic aromatic substitution to install the nitro group ''para'' to the amino group. The amino group can be easily protonated and become a meta director. Therefore, a protection of the acetyl group is required. After this reaction, a separation must be performed to remove 2-nitroaniline, which is also formed in a small amount during the reaction. Applications 4-Nitroaniline is mainly consumed industrially as a precu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Indophenol
Indophenol is an organic compound with the formula OC6H4NC6H4OH. It is deep blue dye that is the product of the Berthelot's reaction, a common test for ammonia. The indophenol group, with various substituents in place of O''H'' and various ring substitutions, is found in many dyes used in hair coloring and textiles. Indophenol is used in hair dyes, lubricants, redox materials, liquid crystal displays, fuel cells and chemical-mechanical polishing. It is an environmental pollutant and is toxic to fish. Berthelot test In the Berthelot test (1859), a sample suspected of having containing ammonia is treated with sodium hypochlorite and phenol. The formation of indophenol is used to determine ammonia and paracetamol by spectrophotometry. Other phenols can be used. Dichlorophenol-indophenol (DCPIP), a form of indophenol, is often used to determine the presence of vitamin C (ascorbic acid). Related compounds Indophenol blue is a different compound with systematic name A systematic n ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Antiozonant
An antiozonant, also known as anti-ozonant, is an organic compound that prevents or retards damage caused by ozone. The most important antiozonants are those which prevent degradation of elastomers like rubber. A number of research projects study the application of another type of antiozonats to protect plants. Effect of ozone Many elastomers are rich in unsaturated double bonds, which can react with ozone present in the air in process known as ozonolysis. This reaction breaks the polymer chains, degrading the mechanical properties of the material. The most obvious effect of this is cracking of the elastomer (ozone cracking), which is exacerbated by mechanical stress. The rate of degradation is effected both by the chemical structure of the elastomer and the amount of ozone in the environment. Elastomers which are rich in double bonds, such as natural rubber, polybutadiene, styrene-butadiene rubber and nitrile rubber are the most sensitive to degradation, whereas butyl rubbe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rubber
Rubber, also called India rubber, latex, Amazonian rubber, ''caucho'', or ''caoutchouc'', as initially produced, consists of polymers of the organic compound isoprene, with minor impurities of other organic compounds. Thailand, Malaysia, and Indonesia are three of the leading rubber producers. Types of polyisoprene that are used as natural rubbers are classified as elastomers. Currently, rubber is harvested mainly in the form of the latex from the rubber tree (''Hevea brasiliensis'') or others. The latex is a sticky, milky and white colloid drawn off by making incisions in the bark and collecting the fluid in vessels in a process called "tapping". The latex then is refined into the rubber that is ready for commercial processing. In major areas, latex is allowed to coagulate in the collection cup. The coagulated lumps are collected and processed into dry forms for sale. Natural rubber is used extensively in many applications and products, either alone or in combination wit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Merck Index
''The Merck Index'' is an encyclopedia of chemical substance, chemicals, pharmaceutical drug, drugs and biomolecule, biologicals with over 10,000 monographs, monograph on single substances or groups of related chemical compound, compounds published online by the Royal Society of Chemistry. History The first edition of the Merck's Index was published in 1889 by the German chemical company Merck Group, Emanuel Merck and was primarily used as a sales catalog for Merck's growing list of chemicals it sold. The American subsidiary was established two years later and continued to publish it. During World War I the US government seized Merck's US operations and made it a separate American "Merck" company that continued to publish the Merck Index. In 2012 the Merck Index was licensed to the Royal Society of Chemistry. An online version of The Merck Index, including historic records and new updates not in the print edition, is commonly available through research libraries. It also include ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
