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Expanded Polystyrene
Polystyrene (PS) is a synthetic polymer made from monomers of the aromatic hydrocarbon styrene. Polystyrene can be solid or foamed. General-purpose polystyrene is clear, hard, and brittle. It is an inexpensive resin per unit weight. It is a poor barrier to oxygen and water vapour and has a relatively low melting point. Polystyrene is one of the most widely used plastics, the scale of its production being several million tonnes per year. Polystyrene can be naturally transparent, but can be colored with colorants. Uses include protective packaging (such as packing peanuts and in the jewel cases used for storage of optical discs such as CDs and occasionally DVDs), containers, lids, bottles, trays, tumblers, disposable cutlery, in the making of models, and as an alternative material for phonograph records. As a thermoplastic polymer, polystyrene is in a solid (glassy) state at room temperature but flows if heated above about 100 °C, its glass transition temperature. ... [...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] |
Extrusion
Extrusion is a process used to create objects of a fixed cross-sectional profile by pushing material through a die of the desired cross-section. Its two main advantages over other manufacturing processes are its ability to create very complex cross-sections; and to work materials that are brittle, because the material encounters only compressive and shear stresses. It also creates excellent surface finish and gives considerable freedom of form in the design process. Drawing is a similar process, using the tensile strength of the material to pull it through the die. It limits the amount of change that can be performed in one step, so it is limited to simpler shapes, and multiple stages are usually needed. Drawing is the main way to produce wire. Metal bars and tubes are also often drawn. Extrusion may be continuous (theoretically producing indefinitely long material) or semi-continuous (producing many pieces). It can be done with hot or cold material. Commonly extruded materials ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
August Wilhelm Von Hofmann
August Wilhelm von Hofmann (8 April 18185 May 1892) was a German chemist who made considerable contributions to organic chemistry. His research on aniline helped lay the basis of the aniline-dye industry, and his research on coal tar laid the groundwork for his student Charles Mansfield's practical methods for extracting benzene and toluene and converting them into nitro compounds and amines. Hofmann's discoveries include formaldehyde, hydrazobenzene, the isonitriles, and allyl alcohol. He prepared three ethylamines and tetraethylammonium compounds and established their structural relationship to ammonia. After studying under Justus von Liebig at the University of Giessen, Hofmann became the first director of the Royal College of Chemistry, now part of Imperial College London, in 1845. In 1865 he returned to Germany to accept a position at the University of Berlin as a teacher and researcher. After his return he co-founded the German Chemical Society (''Deutsche Chemische Gese ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
John Buddle Blyth
John Buddle Blyth (1814 – 24 December 1871) was a Jamaican-born chemist who was the first professor of chemistry at Queen's College Cork in Ireland. With August Wilhelm von Hofmann, he was the first to report photopolymerisation which they observed when styrene became metastyrol after exposure to sunlight. Early life and family John Blyth was born in Jamaica in 1814 to John Blythe and Mary Buddle, a "free woman of colour". He was baptised at Mesopotamia in Westmoreland Parish on 11 April 1816 by Edmund Pope, rector of Westmorland, and described as a "free child of colour".John Buddle Blyth Jamaica, Church of England Parish Register Transcripts, 1664-1880. Family Search. Retrieved 12 January 2019. He had brothers Charles (181 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Liquidambar Orientalis
''Liquidambar Orientalis'', commonly known as oriental sweetgum or Turkish sweetgum, is a deciduous tree in the genus ''Liquidambar'', native to the eastern Mediterranean region, that occurs as pure stands mainly in the floodplains of southwestern Turkey and on the Greek island of Rhodes. Description Oriental sweet gum is a deciduous tree, in height with a trunk of in diameter. The unisexual flowers bloom from March to April. The fruits ripen in November to December and the seeds are wind dispersed. The tree is very attractive and especially valued for its colourful autumn leaves. Oriental sweet gum trees favour an elevation of between , a mean annual rainfall of and a mean annual temperature of . The tree's optimal growth is on rich, deep and moist soils such as bogs, river banks and coastal areas but it is also able to grow on slopes and dry soil. Biotope The forests of this Tertiary relict endemic taxon are found notably within a specially protected area between Dalyan ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Storax
Storax ( la, storax; el, στύραξ, ''stúrax''), often commercially sold as styrax, is a natural resin isolated from the wounded bark of ''Liquidambar orientalis'' Mill. (Asia Minor) and ''Liquidambar styraciflua'' L. (Central America) (Hamamelidaceae). It is distinct from benzoin (also called "storax"), a similar resin obtained from the Styracaceae plant family. Composition Purified storax contains circa 33 to 50% storesin, an alcoholic resin, both free and as cinnamic esters. Contains 5 to 15% cinnamic acid, 5 to 15% cinnamyl cinnamate, circa 10% phenylpropyl cinnamate; small amounts of ethyl cinnamate, benzyl cinnamate, and styrene, Some may contain traces of vanillin. Some sources report a resin containing triterpenic acids ( oleanolic and 3-epioleanolic acids). Uses Storax has a pleasant, floral/lilac, leathery, balsamic smell. Storax and its derivatives ( resinoid, essential oil, absolute) are used as flavors, fragrances, and in pharmaceuticals (Friar's Balsam). ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Apothecary
''Apothecary'' () is a mostly archaic term for a medical professional who formulates and dispenses '' materia medica'' (medicine) to physicians, surgeons, and patients. The modern chemist (British English) or pharmacist (British and North American English) now perform this role. In some languages and regions, the word "apothecary" is still used to refer to a retail pharmacy or a pharmacist who owns one. Apothecaries' investigation of herbal and chemical ingredients was a precursor to the modern sciences of chemistry and pharmacology. In addition to dispensing herbs and medicine, apothecaries offered general medical advice and a range of services that are now performed by other specialist practitioners, such as surgeons and obstetricians. Apothecary shops sold ingredients and the medicines they prepared wholesale to other medical practitioners, as well as dispensing them to patients. In 17th-century England, they also controlled the trade in tobacco which was imported as a me ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Eduard Simon
Johann Eduard Simon (18 September 1789 – 19 June 1856) was an apothecary in Berlin, Germany. Johann Eduard Simon accidentally discovered polystyrene in 1839. Simon distilled an oily substance from storax, the resin of the Sweetgum tree, '' Liquidambar orientalis'', which he named "styrol". Several days later he found that the styrol had thickened, presumably due to polymerisation In polymer chemistry, polymerization (American English), or polymerisation (British English), is a process of reacting monomer molecules together in a chemical reaction to form polymer chains or three-dimensional networks. There are many for ..., into a jelly which he dubbed styrol oxide ("Stryroloxyd").Scheirs, John"Historical Overview of Syrenic Polymers"in References Notes 19th-century German chemists Apothecaries 1789 births 1856 deaths {{Germany-engineer-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Environment (biophysical)
A biophysical environment is a biotic and abiotic surrounding of an organism or population, and consequently includes the factors that have an influence in their survival, development, and evolution. A biophysical environment can vary in scale from microscopic to global in extent. It can also be subdivided according to its attributes. Examples include the marine environment, the atmospheric environment and the terrestrial environment. The number of biophysical environments is countless, given that each living organism has its own environment. The term ''environment'' can refer to a singular global environment in relation to humanity, or a local biophysical environment, e.g. the UK's Environment Agency. Life-environment interaction All life that has survived must have adapted to the conditions of its environment. Temperature, light, humidity, soil nutrients, etc., all influence the species within an environment. However, life in turn modifies, in various forms, its conditions. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Litter
Litter consists of waste products that have been discarded incorrectly, without consent, at an unsuitable location. Litter can also be used as a verb; to litter means to drop and leave objects, often man-made, such as aluminum cans, paper cups, food wrappers, cardboard boxes or plastic bottles on the ground, and leave them there indefinitely or for other people to dispose of as opposed to disposing of them correctly. Large and hazardous items of rubbish such as tires, electrical appliances, electronics, batteries and large industrial containers are sometimes dumped in isolated locations, such as national forests and other public lands. It is a human impact on the environment and remains a serious environmental problem in many countries. Litter can exist in the environment for long periods of time before decomposition and be transported over large distances into the world's oceans. Litter can affect the quality of life. Cigarette butts are the most littered item in the world, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Biodegradable
Biodegradation is the breakdown of organic matter by microorganisms, such as bacteria and fungi. It is generally assumed to be a natural process, which differentiates it from composting. Composting is a human-driven process in which biodegradation occurs under a specific set of circumstances. The process of biodegradation is threefold: first an object undergoes biodeterioration, which is the mechanical weakening of its structure; then follows biofragmentation, which is the breakdown of materials by microorganisms; and finally assimilation, which is the incorporation of the old material into new cells. In practice, almost all chemical compounds and materials are subject to biodegradation, the key element being time. Things like vegetables may degrade within days, while glass and some plastics take many millennia to decompose. A standard for biodegradability used by the European Union is that greater than 90% of the original material must be converted into , water and minerals by ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
ASTM
ASTM International, formerly known as American Society for Testing and Materials, is an international standards organization that develops and publishes voluntary consensus technical standards for a wide range of materials, products, systems, and services. Some 12,575 ASTM voluntary consensus standards operate globally. The organization's headquarters is in West Conshohocken, Pennsylvania, about northwest of Philadelphia. It is founded in 1902 as the American Section of the International Association for Testing Materials (see also International Organization for Standardization). History A group of scientists and engineers, led by Charles Dudley, formed ASTM in 1898 to address the frequent rail breaks affecting the fast-growing railroad industry. The group developed a standard for the steel used to fabricate rails. Originally called the "American Society for Testing Materials" in 1902, it became the "American Society for Testing And Materials" in 1961. In 2001, ASTM official ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
