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Ultra High Molecular Weight Polyethylene
Ultra-high-molecular-weight polyethylene (UHMWPE, UHMW) is a subset of the thermoplastic polyethylene. Also known as high-modulus polyethylene, (HMPE), it has extremely long chains, with a molecular mass usually between 3.5 and 7.5 million amu. The longer chain serves to transfer load more effectively to the polymer backbone by strengthening intermolecular interactions. This results in a very tough material, with the highest impact strength of any thermoplastic presently made. UHMWPE is odorless, tasteless, and nontoxic. It embodies all the characteristics of high-density polyethylene (HDPE) with the added traits of being resistant to concentrated acids and alkalis, as well as numerous organic solvents. It is highly resistant to corrosive chemicals except oxidizing acids; has extremely low moisture absorption and a very low coefficient of friction; is self-lubricating (see boundary lubrication); and is highly resistant to abrasion, in some forms being 15 times more resistant to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thermoplastic
A thermoplastic, or thermosoft plastic, is any plastic polymer material that becomes pliable or moldable at a certain elevated temperature and solidifies upon cooling. Most thermoplastics have a high molecular weight. The polymer chains associate by intermolecular forces, which weaken rapidly with increased temperature, yielding a viscous liquid. In this state, thermoplastics may be reshaped and are typically used to produce parts by various polymer processing techniques such as injection molding, compression molding, calendering, and extrusion. Thermoplastics differ from thermosetting polymers (or "thermosets"), which form irreversible chemical bonds during the curing process. Thermosets do not melt when heated, but typically decompose and do not reform upon cooling. Above its glass transition temperature and below its melting point, the physical properties of a thermoplastic change drastically without an associated phase change. Some thermoplastics do not fully crystallize ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tensile Stress
In continuum mechanics, stress is a physical quantity. It is a quantity that describes the magnitude of forces that cause deformation. Stress is defined as ''force per unit area''. When an object is pulled apart by a force it will cause elongation which is also known as deformation, like the stretching of an elastic band, it is called tensile stress. But, when the forces result in the compression of an object, it is called compressive stress. It results when forces like tension or compression act on a body. The greater this force and the smaller the cross-sectional area of the body on which it acts, the greater the stress. Therefore, stress is measured in newton per square meter (N/m2) or pascal (Pa). Stress expresses the internal forces that neighbouring particles of a continuous material exert on each other, while strain is the measure of the deformation of the material. For example, when a solid vertical bar is supporting an overhead weight, each particle in the bar pushes o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Van Der Waals Forces
In molecular physics, the van der Waals force is a distance-dependent interaction between atoms or molecules. Unlike ionic bond, ionic or covalent bonds, these attractions do not result from a Chemical bond, chemical electronic bond; they are comparatively weak and therefore more susceptible to disturbance. The van der Waals force quickly vanishes at longer distances between interacting molecules. Named after Dutch physicist Johannes Diderik van der Waals, the van der Waals force plays a fundamental role in fields as diverse as supramolecular chemistry, structural biology, polymer science, nanotechnology, surface science, and condensed matter physics. It also underlies many properties of Organic chemistry, organic compounds and molecular solids, including their solubility in Chemical polarity, polar and non-polar media. If no other force is present, the distance between atoms at which the force becomes repulsive rather than attractive as the atoms approach one another is called ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Polyolefin
A polyolefin is a type of polymer with the general formula (CH2CHR)n where R is an alkyl group. They are usually derived from a small set of simple olefins (alkenes). Dominant in a commercial sense are polyethylene and polypropylene. More specialized polyolefins include polyisobutylene and polymethylpentene. They are all colorless or white oils or solids. Many copolymers are known, such as polybutene, which derives from a mixture of different butene isomers. The name of each polyolefin indicates the olefin from which it is prepared; for example, polyethylene is derived from ethylene, and polymethylpentene is derived from 4-methyl-1-pentene. Polyolefins are not olefins themselves because the double bond of each olefin monomer is opened in order to form the polymer. Monomers having more than one double bond such as butadiene and isoprene yield polymers that contain double bonds ( polybutadiene and polyisoprene) and are usually not considered polyolefins. Polyolefins are the foundat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Polyethylene Repeat Unit
Polyethylene or polythene (abbreviated PE; IUPAC name polyethene or poly(methylene)) is the most commonly produced plastic. It is a polymer, primarily used for packaging (plastic bags, plastic films, geomembranes and containers including bottles, etc.). , over 100 million tonnes of polyethylene resins are being produced annually, accounting for 34% of the total plastics market. Many kinds of polyethylene are known, with most having the chemical formula (C2H4)''n''. PE is usually a mixture of similar polymers of ethylene, with various values of ''n''. It can be ''low-density'' or ''high-density'': low-density polyethylene is extruded using high pressure () and high temperature (), while high-density polyethylene is extruded using low pressure () and low temperature (). Polyethylene is usually thermoplastic, but it can be modified to become thermosetting polymer, thermosetting instead, for example, in cross-linked polyethylene. History Polyethylene was first synthesized by th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
DSM (company)
Koninklijke DSM N.V. (Royal DSM, commonly known as DSM), is a Dutch multinational corporation active in the fields of health, nutrition and materials. Headquartered in Heerlen, at the end of 2017 DSM employed 21,054 people in approximately 50 countries and posted net sales of €8.632 billion in 2018 and €9.204 billion in 2021. History DSM was formed by the Dutch state in 1902 to mine coal reserves in southern Limburg and although the company had diversified into commodity chemicals and petrochemicals by 1973 when the last mine closed, DSM retains a link to its origins by continuing to use the initials, originally an abbreviation for Dutch State Mines, to this day. During World War II researchers worked on penicillin. The code name Bacinol was used to keep the research secret from the Germans. The research was done at the company Nederlandsche Gist- en Spiritusfabriek, Dutch Yeast and Spirits Factory, later becoming DSM Sinochem Pharmaceuticals, in Delft. In 1989 the gover ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vertebral Column
The vertebral column, also known as the backbone or spine, is part of the axial skeleton. The vertebral column is the defining characteristic of a vertebrate in which the notochord (a flexible rod of uniform composition) found in all chordata, chordates has been replaced by a segmented series of bone: vertebrae separated by intervertebral discs. Individual vertebrae are named according to their region and position, and can be used as anatomical landmarks in order to guide procedures such as Lumbar puncture, lumbar punctures. The vertebral column houses the spinal canal, a cavity that encloses and protects the spinal cord. There are about 50,000 species of animals that have a vertebral column. The human vertebral column is one of the most-studied examples. Many different diseases in humans can affect the spine, with spina bifida and scoliosis being recognisable examples. The general structure of human vertebrae is fairly typical of that found in mammals, reptiles, and birds. Th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Orthopedic
Orthopedic surgery or orthopedics ( alternatively spelt orthopaedics), is the branch of surgery concerned with conditions involving the musculoskeletal system. Orthopedic surgeons use both surgical and nonsurgical means to treat musculoskeletal trauma, spine diseases, sports injuries, degenerative diseases, infections, tumors, and congenital disorders. Etymology Nicholas Andry coined the word in French as ', derived from the Ancient Greek words ὀρθός ''orthos'' ("correct", "straight") and παιδίον ''paidion'' ("child"), and published ''Orthopedie'' (translated as ''Orthopædia: Or the Art of Correcting and Preventing Deformities in Children'') in 1741. The word was assimilated into English as ''orthopædics''; the ligature ''æ'' was common in that era for ''ae'' in Greek- and Latin-based words. As the name implies, the discipline was initially developed with attention to children, but the correction of spinal and bone deformities in all stages of life eventually ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Arthroplasty
Arthroplasty (literally " e-orming of joint") is an orthopedic surgical procedure where the articular surface of a musculoskeletal joint is replaced, remodeled, or realigned by osteotomy or some other procedure. It is an elective procedure that is done to relieve pain and restore function to the joint after damage by arthritis or some other type of trauma. Types For the last 45 years, the most successful and common form of arthroplasty is the surgical replacement of arthritic or destructive or necrotic joint or joint surface with a prosthesis. For example, a hip joint that is affected by osteoarthritis may be replaced entirely (total hip arthroplasty) with a prosthetic hip. This would involve replacing both the acetabulum (hip socket) and the head and neck of the femur. The purpose of this procedure is to relieve pain, to restore range of motion and to improve walking ability, thus leading to the improvement of muscle strength. Other types of arthroplasty * Interposition ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mitsui Chemicals
is a Japanese chemicals company listed on the Nikkei with business interests in Japan, Europe, China, Southeast Asia and the USA. It is one of the leading chemical companies in Japan and is part of the Mitsui conglomerate. The company mainly deals in performance materials, petrochemicals and basic chemicals and functional polymeric materials. History Mitsui Chemicals of the Mitsui group emerged in 1968 with the merger of Toyo Koatsu and Mitsui Chemical Industry. The former was established in 1933 and was mainly engaged in the manufacture of fertilizers while the latter was founded in 1941 and produced dyes and organic intermediates. The new entity focused in the production of four product lines: fertilizers; basic products (methanol, formaldehyde, phenol, aniline, bisphenol A, TDI, MDI, and melamine); polymers; and, fine chemicals. With the growth of opportunities in India, Mitsui Chemicals has decided to establish its first polypropylene compounding plant in India at 'Japa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Celanese
Celanese Corporation, formerly known as Hoechst Celanese, is an American technology and specialty materials company headquartered in Irving, Texas. A Fortune 500 corporation, the company is the world’s leading producer of acetic acid, producing about 1.95 million tonnes per year, representing approximately 25% of global production. Celanese is also the world's largest producer of vinyl acetate monomer (VAM). Celanese operates 25 production plants and six research centers in 11 countries, mainly in North America, Europe, and Asia. The company owns and operates the world's three largest acetic acid plants: one in the Clear Lake area of Pasadena, Texas, one on Jurong Island in Singapore, and a third in Nanjing, China. History In 1918, the American Cellulose & Chemical Manufacturing Company (known as Amcelle) was founded in New York City by Swiss chemist Camille Dreyfus. The American Cellulose and Chemical Manufacturing Co. Ltd plant in Cumberland, Maryland, was set up dur ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
