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Synthetic Resins
Synthetic resins are industrially produced resins, typically viscous substances that convert into rigid polymers by the process of curing. In order to undergo curing, resins typically contain reactive end groups, such as acrylates or epoxides. Some synthetic resins have properties similar to natural plant resins, but many do not. Synthetic resins are of several classes. Some are manufactured by esterification of organic compounds. Some are thermosetting plastics in which the term "resin" is loosely applied to the reactant(s), the product, or both. "Resin" may be applied to one of two monomers in a copolymer, the other being called a "hardener", as in epoxy resins. For thermosetting plastics that require only one monomer, the monomer compound is the "resin". For example, liquid methyl methacrylate is often called the "resin" or "casting resin" while in the liquid state, before it polymerizes and "sets". After setting, the resulting poly(methyl methacrylate) (PMMA) is often rename ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Polyurethane
Polyurethane (; often abbreviated PUR and PU) refers to a class of polymers composed of organic chemistry, organic units joined by carbamate (urethane) links. In contrast to other common polymers such as polyethylene and polystyrene, polyurethane is produced from a wide range of starting materials. This chemical variety produces polyurethanes with different chemical structures leading to many List of polyurethane applications, different applications. These include rigid and flexible foams, varnishes and coatings, adhesives, Potting (electronics), electrical potting compounds, and fibers such as spandex and Polyurethane laminate, PUL. Foams are the largest application accounting for 67% of all polyurethane produced in 2016. A polyurethane is typically produced by reacting an isocyanate with a polyol. Since a polyurethane contains two types of monomers, which polymerize one after the other, they are classed as Copolymer#Alternating copolymers, alternating copolymers. Both the isocy ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bis-GMA
Bis-GMA (bisphenol A-glycidyl methacrylate) is a resin commonly used in dental composite, dental sealants. and dental cement. It is the diester derived from methacrylic acid and the bisphenol A diglycidyl ether. Bearing two polymerizable groups, it is prone to form a crosslinked polymer that is used in dental restorations. For dental work, highly viscous bis-GMA is mixed with aluminosilicate particles, crushed quartz and other related acrylates; changes to component ratios lead to different physical properties in the end product. Bis-GMA was incorporated into composite dental resins in 1962 by Rafael Bowen. Until matrix development work in the early 2000s, bis-GMA and related methacrylate monomers were the only options for organic matrix composition. Safety Concerns have been raised about the potential for bis-GMA to break down into or be contaminated with the related compound bisphenol A. However, no negative health effects of bis-GMA use in dental resins have been found. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Unsaturated 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 materials are a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Solvent Impregnated Resin
Solvent impregnated resins (SIRs) are commercially available (macro)porous resins impregnated with a solvent/an extractant. In this approach, a liquid extractant is contained within the pores of (adsorption) particles. Usually, the extractant is an organic liquid. Its purpose is to extract one or more dissolved components from a surrounding aqueous environment. The basic principle combines adsorption, chromatography and liquid-liquid extraction. History The principle of Solvent Impregnated Resins was first shown in 1971 by Abraham Warshawsky. This first venture was aimed at the extraction of metals. Ever since then, SIRs have been mainly used for metal extraction, be it heavy metals or specifically radioactive metals. Much research on SIRs has been done by J.L Cortina and e.g. N. Kabay, K. Jerabek or J. Serarols. However, lately investigations also go towards using SIRs for the separation of natural compounds, and even for separation of biotechnological products. Basic principle ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hypolipidemic Agent
Lipid-lowering agents, also sometimes referred to as hypolipidemic agents, cholesterol-lowering drugs, or antihyperlipidemic agents are a diverse group of pharmaceuticals that are used to lower the level of lipids and lipoproteins such as cholesterol, in the blood (hyperlipidemia). The American Heart Association recommends the descriptor 'lipid lowering agent' be used for this class of drugs rather than the term 'hypolipidemic'. Classes The several classes of lipid lowering drugs may differ in both their impact on the cholesterol profile and adverse effects. For example, some may lower low density lipoprotein (LDL) levels more so than others, while others may preferentially increase high density lipoprotein (HDL). Clinically, the choice of an agent depends on the patient's cholesterol profilecardiovascular risk and the liver and kidney functions of the patient, evaluated against the balancing of risks and benefits of the medications. In the United States, this is guided by the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
