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Polystyrene Foam
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 air and water vapor and has a relatively low melting point. Polystyrene is one of the most widely used plastics, with the scale of its production being several million tonnes per year. Polystyrene is naturally transparent to visible light, but can be colored with colorants. Uses include protective packaging (such as packing peanuts and optical disc jewel cases), 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. It becomes rigid again when cooled. This temperat ... [...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 (som ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thermoplastic
A thermoplastic, or thermosoftening 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 ... [...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 Basin, Mediterranean region, that occurs as pure stands mainly in the floodplains of southwestern Turkey and on the Greece, 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. The bark is not cracked when young but fissured when old. The bark is grayish when young and tur ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Storax
Storax (; , ''stúrax''), often commercially sold as styrax, is a natural fragrant resin isolated from the wounded bark of ''Liquidambar orientalis'' Mill. (Asia Minor) and ''Liquidambar styraciflua'' L. (Eastern US, Mexico, Central America) (Altingiaceae). It is distinct from Benzoin resin, benzoin (also called "storax"), a similar resin obtained from the Styracaceae plant family. Composition Purified storax contains circa 33–50% storesin, an Alcohol (chemistry), alcoholic resin, both free and as cinnamic esters. It contains 5–15% cinnamic acid, 5–15% 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 acid, oleanolic and 3-epioleanolic acids). Uses Storax has a pleasant, floral/lilac, leathery, balsamic smell. Storax and its derivatives (Resinoid (perfumery), resinoid, essential oil, Absolute (perfumer ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Apothecary
''Apothecary'' () is an Early Modern English, archaic English term for a medicine, medical professional who formulates and dispenses ''materia medica'' (medicine) to physicians, surgeons and patients. The modern terms ''pharmacist'' and, in British English, ''chemist'' have taken over this role. In some languages and regions, terms similar to "apothecary" have survived and denote modern pharmacies or pharmacists. Apothecaries' investigation of Herbal medicine, 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 Obstetrics and gynaecology, 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 contro ... [...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 Storax (; , ''stúrax''), often commercially sold as styrax, is a natural fragrant resin isolated from the wounded bark of ''Liquidambar orientalis'' Mill. (Asia Minor) and ''Liquidambar styraciflua'' L. (Eastern US, Mexico, Central America) (A ..., 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, into a jelly which he dubbed styrol oxide ("Stryroloxyd").Scheirs, John"Historical Overview of Syrenic Polymers"in Notes 19th-century German chemists German apothecaries 1789 births 1856 deaths Chemists from the Kingdom of Prussia {{Germany-engineer-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Environment (biophysical)
The natural environment or natural world encompasses all biotic and abiotic things occurring naturally, meaning in this case not artificial. The term is most often applied to Earth or some parts of Earth. This environment encompasses the interaction of all living species, climate, weather and natural resources that affect human survival and economic activity. The concept of the ''natural environment'' can be distinguished as components: * Complete ecological units that function as natural systems without massive civilized human intervention, including all vegetation, microorganisms, soil, rocks, plateaus, mountains, the atmosphere and natural phenomena that occur within their boundaries and their nature. * Universal natural resources and physical phenomena that lack clear-cut boundaries, such as air, water and climate, as well as energy, radiation, electric charge and magnetism, not originating from civilized human actions. In contrast to the natural environment is the ... [...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. The waste is objects, often man-made, such as aluminum cans, paper cups, food wrappers, cardboard boxes or plastic bottles, but also 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. Litter is a type of human impact on the environment and is 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 negatively affect quality of life. Cigarette#Cigarette butt, Cigarette butts are the most littered item in the world, with an estimated 4.5 trillion discarded each year. Estimates of the required time for cigarette butts to break down vary, ranging fro ... [...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 b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
ASTM
ASTM International, formerly known as American Society for Testing and Materials, is a standards organization that develops and publishes voluntary consensus technical international standards for a wide range of materials, products, systems and services. Some 12,575 apply globally. The headquarters is in West Conshohocken, Pennsylvania, about northwest of Philadelphia. It was founded in 1902 as the American Section of the International Association for Testing Materials. In addition to its traditional standards work, ASTM operates several global initiatives advancing additive manufacturing, advanced manufacturing, and emerging technologies, including the Additive Manufacturing Center of Excellence (AM CoE), the acquisition oWohlers Associatesfor market intelligence and advisory services, and the NIST-funded Standardization Center of Excellence (SCOE). History In 1898, a group of scientists and engineers, led by chemist, industry leader, and proponent of standardization Ch ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vacuum Forming
Vacuum forming is a simplified version of thermoforming, where a sheet of plastic in various forms of High Impact Polystyrene Sheet (HIPS) for low impact products, or ABS for bathroom shower trays, and HDPE for exterior vehicle parts, plus various other types of vacuum formable materials) is heated to a forming temperature, stretched onto a single-surface moulding (process), mould, and forced against the mould by a vacuum. This process can be used to form plastic into permanent objects such as turnpike signs and protective covers. Normally draft angles are present in the design of the mould (a recommended minimum of 3°) to ease removal of the formed plastic part from the mould. Relatively deep parts can be formed if the formability, formable sheet is mechanically or pneumatically stretched prior to bringing it into contact with the mold surface and applying the vacuum. Suitable materials for use in vacuum forming are conventionally thermoplastics. The most common and easiest t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Molding (process)
Molding (American English) or moulding ( British and Commonwealth English; see spelling differences) is the process of manufacturing by shaping liquid or pliable raw material using a rigid frame called a mold or matrix. This itself may have been made using a pattern or model of the final object. A mold or mould is a hollowed-out block that is filled with a liquid or pliable material such as plastic, glass, metal, or ceramic raw material. The liquid hardens or sets inside the mold, adopting its shape. A mold is a counterpart to a cast. The very common bi-valve molding process uses two molds, one for each half of the object. Articulated molds have multiple pieces that come together to form the complete mold, and then disassemble to release the finished casting; they are expensive, but necessary when the casting shape has complex overhangs. Piece-molding uses a number of different molds, each creating a section of a complicated object. This is generally only used for larg ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
