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Ethyl Cyanoacrylate
Ethyl cyanoacrylate (ECA), a cyanoacrylate ester, is an ethyl ester of 2-cyano-2-propenoic acid. It is a colorless liquid with low viscosity and a faint sweet smell in pure form. It is the main component of cyanoacrylate glues and can be encountered under many trade names. It is soluble in acetone, methyl ethyl ketone, nitromethane, and methylene chloride. ECA polymerizes rapidly in presence of moisture. Production Ethyl cyanoacrylate is prepared by the condensation of formaldehyde with ethyl cyanoacetate: : + → + This exothermic reaction affords the polymer, which is subsequently sintered, thermally "cracked" to give the monomer. Alternatively, it can be prepared by the ethoxycarbonylation of cyanoacetylene. Applications Ethyl cyanoacrylate is used for gluing various materials. It is also used in medicine, for liquid bandages and for suture-less surgery, but it is used less often than the less toxic ''n''-butyl and octyl cyanoacrylates. Off-the-shelf consumer ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cyanoacrylate
Cyanoacrylates are a family of strong fast-acting adhesives with industrial, medical, and household uses. They are derived from ethyl cyanoacrylate and related esters. The cyanoacrylate group in the monomer rapidly polymerizes in the presence of water to form long, strong chains. They have some minor toxicity. Specific cyanoacrylates include methyl 2-cyanoacrylate (MCA), ethyl 2-cyanoacrylate (ECA, commonly sold under trade names such as "Super Glue" and "Krazy Glue", or Toagosei), ''n''-butyl cyanoacrylate (n-BCA), octyl cyanoacrylate, and 2-octyl cyanoacrylate (used in medical, veterinary and first aid applications). Octyl cyanoacrylate was developed to address toxicity concerns and to reduce skin irritation and allergic response. Cyanoacrylate adhesives are sometimes known generically as instant glues, power glues or superglues. The abbreviation "CA" is commonly used for industrial grade cyanoacrylate. Development The original patent for cyanoacrylate was filed in 1 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sintering
Clinker nodules produced by sintering Sintering or frittage is the process of compacting and forming a solid mass of material by pressure or heat without melting it to the point of liquefaction. Sintering happens as part of a manufacturing process used with metals, ceramics, plastics, and other materials. The atoms in the materials diffuse across the boundaries of the particles, fusing the particles together and creating one solid piece. Because the sintering temperature does not have to reach the melting point of the material, sintering is often chosen as the shaping process for materials with extremely high melting points such as tungsten and molybdenum. The study of sintering in metallurgical powder-related processes is known as powder metallurgy. An example of sintering can be observed when ice cubes in a glass of water adhere to each other, which is driven by the temperature difference between the water and the ice. Examples of pressure-driven sintering are the compact ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lung
The lungs are the primary organs of the respiratory system in humans and most other animals, including some snails and a small number of fish. In mammals and most other vertebrates, two lungs are located near the backbone on either side of the heart. Their function in the respiratory system is to extract oxygen from the air and transfer it into the bloodstream, and to release carbon dioxide from the bloodstream into the atmosphere, in a process of gas exchange. Respiration is driven by different muscular systems in different species. Mammals, reptiles and birds use their different muscles to support and foster breathing. In earlier tetrapods, air was driven into the lungs by the pharyngeal muscles via buccal pumping, a mechanism still seen in amphibians. In humans, the main muscle of respiration that drives breathing is the diaphragm. The lungs also provide airflow that makes vocal sounds including human speech possible. Humans have two lungs, one on the left an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Depolymerization
Depolymerization (or depolymerisation) is the process of converting a polymer into a monomer or a mixture of monomers. This process is driven by an increase in entropy. Ceiling temperature The tendency of polymers to depolymerize is indicated by their ceiling temperature. At this temperature, the enthalpy of polymerization matches the entropy gained by converting a large molecule into monomers. Above the ceiling temperature, the rate of depolymerization is greater than the rate of polymerization, which inhibits the formation of the given polymer. Applications Depolymerization is a very common process. Digestion of food involves depolymerization of macromolecules, such as proteins. It is relevant to polymer recycling. Sometimes the depolymerization is well behaved, and clean monomers can be reclaimed and reused for making new plastic. In other cases, such as polyethylene, depolymerization gives a mixture of products. These products are, for polyethylene, ethylene, propylene ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
MegaHertz
The hertz (symbol: Hz) is the unit of frequency in the International System of Units (SI), equivalent to one event (or cycle) per second. The hertz is an SI derived unit whose expression in terms of SI base units is s−1, meaning that one hertz is the reciprocal of one second. It is named after Heinrich Rudolf Hertz (1857–1894), the first person to provide conclusive proof of the existence of electromagnetic waves. Hertz are commonly expressed in multiples: kilohertz (kHz), megahertz (MHz), gigahertz (GHz), terahertz (THz). Some of the unit's most common uses are in the description of periodic waveforms and musical tones, particularly those used in radio- and audio-related applications. It is also used to describe the clock speeds at which computers and other electronics are driven. The units are sometimes also used as a representation of the energy of a photon, via the Planck relation ''E'' = ''hν'', where ''E'' is the photon's energy, ''ν'' is its frequ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dielectric Constant
The relative permittivity (in older texts, dielectric constant) is the permittivity of a material expressed as a ratio with the electric permittivity of a vacuum. A dielectric is an insulating material, and the dielectric constant of an insulator measures the ability of the insulator to store electric energy in an electrical field. Permittivity is a material's property that affects the Coulomb force between two point charges in the material. Relative permittivity is the factor by which the electric field between the charges is decreased relative to vacuum. Likewise, relative permittivity is the ratio of the capacitance of a capacitor using that material as a dielectric, compared with a similar capacitor that has vacuum as its dielectric. Relative permittivity is also commonly known as the dielectric constant, a term still used but deprecated by standards organizations in engineering as well as in chemistry. Definition Relative permittivity is typically denoted as (sometimes ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Octyl Cyanoacrylate
Octyl cyanoacrylate (OCA), a cyanoacrylate ester, is an octyl ester of 2-cyano-2-propenoic acid. It is a clear colorless liquid with a sharp, irritating odor. Its chief use is as the main component of medical cyanoacrylate glues. In medical and veterinary applications, OCA, ''n''-butyl cyanoacrylate (n-BCA) and isobutyl cyanoacrylate (ICA) are commonly used. They provide rapid wound closure, are bacteriostatic, and their use is usually painless. Butyl esters provide a stronger bond, but the glue is rigid. The octyl ester, while providing weaker bond, is more flexible. Blends of OCA and n-BCA are available which offer both flexibility and a strong bond. It polymerizes rapidly in presence of moisture. Heating to higher temperatures causes pyrolysis and depolymerization of the cured glue, producing gaseous products strongly irritating to the lungs and eyes. References {{reflist See also * Methyl cyanoacrylate * Ethyl cyanoacrylate * Butyl cyanoacrylate ''n''-Butyl cyanoacr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Butyl Cyanoacrylate
''n''-Butyl cyanoacrylate (n-BCA, NBCA), a cyanoacrylate ester, is a butyl ester of 2-cyano-2-propenoic acid. It is a colorless liquid with a sharp, irritating odor. It is insoluble in water. Its chief use is as the main component of medical cyanoacrylate glues. It can be encountered under various trade names, e.g. Cutseal, MediBond, MediCryl, PeriAcryl, GluStitch, Xoin, Gesika, VetGlu, Vetbond, LiquiVet, Indermil, LiquiBand, Histoacryl, IFABond, CutisSeal and others. The generic international nonproprietary name (INN) for NBCA is enbucrilate. In medical and veterinary applications, NBCA, isobutyl cyanoacrylate, and octyl cyanoacrylate are commonly used. They are bacteriostatic and their use is usually painless. Butyl esters provide stronger bond, but are rigid. Octyl esters, while providing weaker bond, are more flexible. Blends of octyl cyanoacrylate and n-butyl cyanoacrylate are available (such as GLUture) which offer both flexibility and a strong bond. n-Butyl cyanoacryl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Surgical Suture
A surgical suture, also known as a stitch or stitches, is a medical device used to hold body tissues together and approximate wound edges after an injury or surgery. Application generally involves using a needle with an attached length of thread. There are numerous types of suture which differ by needle shape and size as well as thread material and characteristics. Selection of surgical suture should be determined by the characteristics and location of the wound or the specific body tissues being approximated. In selecting the needle, thread, and suturing technique to use for a specific patient, a medical care provider must consider the tensile strength of the specific suture thread needed to efficiently hold the tissues together depending on the mechanical and shear forces acting on the wound as well as the thickness of the tissue being approximated. One must also consider the elasticity of the thread and ability to adapt to different tissues, as well as the memory of the thre ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cyanoacetylene
Cyanoacetylene is an organic compound with formula or . It is the simplest cyanopolyyne. Cyanoacetylene has been detected by spectroscopy, spectroscopic methods in interstellar clouds, in the Coma (cometary), coma of comet Hale–Bopp and in the atmosphere of Saturn's moon titan (moon), Titan, where it sometimes forms expansive fog-like clouds. Cyanoacetylene is one of the molecules that was produced in the Miller–Urey experiment. : H-C#C-H + H-C#N -> H-C#C-C#N + H2 See also *Dicyanoacetylene, N≡C−C≡C−C≡N *Diacetylene, H−C≡C−C≡C−H *Cyanogen, N≡C−C≡N *Hydrocyanic acid, H−C≡N *Polyyne, R−(C≡C)''n''−R References {{Authority control Alkyne derivatives Conjugated nitriles ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
