|
Polyesters
Polyester is a category of polymers that contain one or two ester linkages in every repeat unit of their main chain. As a specific material, it most commonly refers to a type called polyethylene terephthalate (PET). Polyesters include some naturally occurring chemicals, such as those found in plants and insects. Natural polyesters and a few synthetic ones are biodegradable, but most synthetic polyesters are not. Synthetic polyesters are used extensively in clothing. Polyester fibers are sometimes spun together with natural fibers to produce a cloth with blended properties. Cotton-polyester blends can be strong, wrinkle- and tear-resistant, and reduce shrinking. Synthetic fibers using polyester have high water, wind, and environmental resistance compared to plant-derived fibers. They are less Fireproofing, fire-resistant and can melt when ignited. Liquid crystalline polyesters are among the first industrially used liquid crystal polymers. They are used for their mechanical propert ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Polyethylene Terephthalate
Polyethylene terephthalate (or poly(ethylene terephthalate), PET, PETE, or the obsolete PETP or PET-P), is the most common thermoplastic polymer resin of the polyester family and is used in synthetic fibre, fibres for clothing, packaging, containers for liquids and foods, and thermoforming for manufacturing, and in combination with glass fibre for engineering resins. In 2016, annual production of PET was 56 million tons. The biggest application is in fibres (in excess of 60%), with bottle production accounting for about 30% of global demand. In the context of textile applications, PET is referred to by its common name, polyester, whereas the acronym ''PET'' is generally used in relation to packaging. PET used in non-fiber applications (i.e. for packaging) makes up about 6% of world polymer production by mass. Accounting for the >60% fraction of polyethylene terephthalate produced for use as polyester fibers, PET is the fourth-most-produced polymer after polyethylene (PE), polypr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Polyester Resin
Polyester resins are synthetic resins formed by the reaction of dibasic organic acids and polyhydric alcohols. Maleic anhydride is a commonly used raw material with diacid functionality in unsaturated polyester resins. Unsaturated polyester resins are used in sheet moulding compound, bulk moulding compound and the toner of laser printers. Wall panels fabricated from polyester resins reinforced with fiberglassso-called fiberglass reinforced plastic (FRP)are typically used in restaurants, kitchens, restrooms and other areas that require washable low-maintenance walls. They are also used extensively in cured-in-place pipe applications. Departments of Transportation in the USA also specify them for use as overlays on roads and bridges. In this application they are known AS Polyester Concrete Overlays (PCO). These are usually based on isophthalic acid and cut with styrene at high levelsusually up to 50%. Polyesters are also used in anchor bolt adhesives though epoxy based materi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Polymer
A polymer () is a chemical substance, substance or material that consists of very large molecules, or macromolecules, that are constituted by many repeat unit, repeating subunits derived from one or more species of monomers. Due to their broad spectrum of properties, both synthetic and natural polymers play essential and ubiquitous roles in everyday life. Polymers range from familiar synthetic plastics such as polystyrene to natural biopolymers such as DNA and proteins that are fundamental to biological structure and function. Polymers, both natural and synthetic, are created via polymerization of many small molecules, known as monomers. Their consequently large molecular mass, relative to small molecule compound (chemistry), compounds, produces unique physical property, physical properties including toughness, high rubber elasticity, elasticity, viscoelasticity, and a tendency to form Amorphous solid, amorphous and crystallization of polymers, semicrystalline structures rath ... [...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] |
Colletes
The genus ''Colletes'' (plasterer bees or cellophane bees) is a large group of ground-nesting bees of the family Colletidae. They occur primarily in the Northern Hemisphere, although have a broad distribution except for Australasia and Antarctica. They tend to be solitary, but sometimes nest close together in aggregations. Species in the genus build cells in underground nests that are lined with a cellophane-like plastic secretion, a true polyester,Hefetz, A., et al. (1979)Natural polyesters: Dufour's gland macrocyclic lactones form brood cell laminesters in ''Colletes'' bees.''Science'' 204(4391), 415-17. earning them the nickname polyester bees.Eveleth, R. and D. ChachraCan Bees Make Tupperware?''Scientific American'' December 19, 2011. there were about 469 described species, and an estimated total around 700.Proshchalykin, M. Y. and M. Kuhlmann. (2012)The bees of the genus ''Colletes'' Latreille 1802 of the Ukraine, with a key to species (Hymenoptera: Apoidea: Colletidae ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Liquid Crystal Polymer
Liquid crystal polymers (LCPs) are polymers with the property of liquid crystal, usually containing aromatic rings as mesogens. Despite uncrosslinked LCPs, polymeric materials like liquid crystal elastomers (LCEs) and liquid crystal networks (LCNs) can exhibit liquid crystallinity as well. They are both crosslinked LCPs but have different cross link density. They are widely used in the digital display market. In addition, LCPs have unique properties like thermal actuation, anisotropic swelling, and soft elasticity. Therefore, they can be good actuators and sensors. One of the most famous and classical applications for LCPs is Kevlar, a strong but light fiber with wide applications, notably bulletproof vests. Background Liquid crystallinity in polymers may occur either by dissolving a polymer in a solvent (lyotropic liquid-crystal polymers) or by heating a polymer above its glass or melting transition point (thermotropic liquid-crystal polymers). Liquid-crystal polymers are ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Definition Polyester Ester Group
A definition is a statement of the meaning of a term (a word, phrase, or other set of symbols). Definitions can be classified into two large categories: intensional definitions (which try to give the sense of a term), and extensional definitions (which try to list the objects that a term describes).Lyons, John. "Semantics, vol. I." Cambridge: Cambridge (1977). p.158 and on. Another important category of definitions is the class of ostensive definitions, which convey the meaning of a term by pointing out examples. A term may have many different senses and multiple meanings, and thus require multiple definitions. In mathematics, a definition is used to give a precise meaning to a new term, by describing a condition which unambiguously qualifies what the mathematical term is and is not. Definitions and axioms form the basis on which all of modern mathematics is to be constructed. Basic terminology In modern usage, a definition is something, typically expressed in words, that at ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Omega Hydroxy Acid
Omega hydroxy acids (ω-hydroxy acids) are a class of naturally occurring straight-chain aliphatic organic acids ''n'' carbon atoms long with a carboxyl group at position 1 (the starting point for the family of carboxylic acids), and a hydroxyl at terminal position ''n'' where ''n'' > 3. They are a subclass of hydroxycarboxylic acids. The C16 and C18 omega hydroxy acids 16-hydroxy palmitic acid and 18-hydroxy stearic acid are key monomers of cutin in the plant cuticle. The polymer cutin is formed by interesterification of omega hydroxy acids and derivatives of them that are substituted in mid-chain, such as 10,16-dihydroxy palmitic acid.T.J. Walton TJ and P.E. Kolattukudy (1972) Enzymatic conversion of 16-hydroxypalmitic acid into 10,16-dihydroxypalmitic acid in ''Vicia faba'' epidermal extracts. Biochem Biophys Res Communications 46, (1), 16–21P. J. Holloway (1982) The chemical constitution of plant cutins. p45-85 in In "The Plant Cuticle". ed. by DF Cutler, KL Alvin and CE Price. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sorona
Sorona is DuPont de Nemours, Inc.'s brand of Triexta, a subclass of polytrimethylene terephthalate (PTT) named and commercialized in 2000. The fibers are soft and stain-resistant while exhibiting high strength and stiffness. Sorona is a co-polymer of 1,3-propanediol (obtained by fermentation) and petroleum-derived terephthalic acid (TPA) or dimethyl terephthalate (DMT). Related polymers in this series include polyethylene terephthalate (2GT) and polybutylene terephthalate (polytetramethylene terephthalate) (4GT). Sorona can theoretically be produced from about 37% renewable resources as DuPont won a 2003 Presidential Green Chemistry Challenge Award for their development of the fermentation process for the production of 1,3-propanediol from corn-derived glucose in recombinant ''Escherichia coli'' K-12. The polymer Sorona has been mentioned by J. Craig Venter in interviews as an example of an application of industrial biotechnology. He was quoted as saying, "DuPont argues ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cellophane
Cellophane is a thin, transparent sheet made of regenerated cellulose. Its low permeability to air, oils, greases, bacteria, and liquid water makes it useful for food packaging. Cellophane is highly permeable to water vapour, but may be coated with nitrocellulose lacquer to prevent this. Cellophane is also used in transparent pressure-sensitive tape, tubing, and many other similar applications. Cellophane is compostable and biodegradable, and can be obtained from biomaterials. The original production process uses carbon disulfide (CS2), which has been found to be highly toxic to workers. The newer lyocell process can be used to produce cellulose film without involving carbon disulfide. "Cellophane" is a generic term in some countries, while in other countries it is a registered trademark owned by DuPont. Production Cellulose is produced from wood, cotton, hemp, and other organic fibres, dissolved in alkali and carbon disulfide to make a solution of liquid viscose. The s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
