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27-454: The reason for the unusual name of the river is that when a group of trappers were attacked by a band of Ute Native Americans , only two men survived, one of whom was injured. Leaving his wounded friend in a cave close by, the last man left to summon help, but not before hanging a frying pan in a tree so that he could find the cave again on his return. It rises in northeastern Pitkin County , in

54-545: A carbonyl group require more complex synthesis due to the way in which reactants polymerize. As alkenes can polymerize in somewhat straightforward radical reactions, they form useful compounds such as polyethylene and polyvinyl chloride (PVC), which are produced in high tonnages each year due to their usefulness in manufacturing processes of commercial products, such as piping, insulation and packaging. In general, polymers such as PVC are referred to as " homopolymers ", as they consist of repeated long chains or structures of

81-426: A free radical , cation , or anion . Once the growth of a chain is initiated by formation of an active center, chain propagation is usually rapid by addition of a sequence of monomers. Long chains are formed from the beginning of the reaction. Chain-growth polymerization (or addition polymerization) involves the linking together of unsaturated monomers, especially containing carbon-carbon double bonds . The pi-bond

108-464: A countertop. (The legs usually attach to handles.) Electric frying pans are common in shapes that are unusual for 'unpowered' frying pans, notably square and rectangular. Most are designed with straighter sides than their stovetop cousins and include a lid. In this way they are a cross between a frying pan and a sauté pan. A modern electric skillet has an additional advantage over the stovetop version: heat regulation. The detachable power cord incorporates

135-417: A large number of copper pans are sold with a tin lining which can be replaced when it wears out. Cast iron pans are used because although they do not conduct heat very evenly, they do retain it quite well, making them useful for searing meats and vegetables. Carbon steel cookware is used because over time it can develop a highly nonstick patina of polymerized oil called seasoning useful for cooking protein that

162-583: A long handle, and no lid. Larger pans may have a small grab handle opposite the main handle. A pan of similar dimensions, but with less flared, more vertical sides and often with a lid, is called a sauté pan . While a sauté pan can be used as a frying pan, it is designed for lower-heat cooking. Copper frying pans were used in ancient Mesopotamia . Frying pans were also known in ancient Greece , where they were called tagēnon ( Ancient Greek : τάγηνον ) and teganon (τήγανον) and Rome , where they were called patella or sartago . The word pan derives from

189-406: A thermostatic control for maintaining the desired temperature. With the perfection of the thermostatic control, the electric skillet became a popular kitchen appliance. Although it largely has been supplanted by the microwave oven , it is still in use in many kitchens. Polymerization In polymer chemistry , polymerization ( American English ), or polymerisation ( British English ),

216-401: A very slow rate at lower conversions and reach moderately high molecular weights only at very high conversion (i.e., >95%). Solid state polymerization to afford polyamides (e.g., nylons) is an example of step-growth polymerization. In chain-growth (or chain) polymerization, the only chain-extension reaction step is the addition of a monomer to a growing chain with an active center such as

243-410: Is a pan used to make rappie pie , an Acadian potato dish. The pan is made from aluminum or stainless steel . Traditionally, frying pans were made of cast iron , carbon steel or copper lined with tin, for their different qualities and properties. Copper pans are highly thermally conductive, making them useful for evenly sautéing. However, they are also highly reactive with most foods, so today

270-594: Is a process of reacting monomer molecules together in a chemical reaction to form polymer chains or three-dimensional networks. There are many forms of polymerization and different systems exist to categorize them. In chemical compounds , polymerization can occur via a variety of reaction mechanisms that vary in complexity due to the functional groups present in the reactants and their inherent steric effects . In more straightforward polymerizations, alkenes form polymers through relatively simple radical reactions ; in contrast, reactions involving substitution at

297-498: Is an exceptionally reactive electrophile it allows nucleophilic addition of hemiacetal intermediates, which are in general short-lived and relatively unstable "mid-stage" compounds that react with other non-polar molecules present to form more stable polymeric compounds. Polymerization that is not sufficiently moderated and proceeds at a fast rate can be very hazardous. This phenomenon is known as autoacceleration , and can cause fires and explosions. Step-growth and chain-growth are

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324-678: Is lost by formation of a new sigma bond. Chain-growth polymerization is involved in the manufacture of polymers such as polyethylene , polypropylene , polyvinyl chloride (PVC), and acrylate . In these cases, the alkenes RCH=CH 2 are converted to high molecular weight alkanes (-RCHCH 2 -) n (R = H, CH 3 , Cl, CO 2 CH 3 ). Other forms of chain growth polymerization include cationic addition polymerization and anionic addition polymerization . A special case of chain-growth polymerization leads to living polymerization . Ziegler–Natta polymerization allows considerable control of polymer branching . Diverse methods are employed to manipulate

351-594: Is not initiated because each growth step requires the assistance of light. Photopolymerization can be used as a photographic or printing process because polymerization only occurs in regions which have been exposed to light. Unreacted monomer can be removed from unexposed regions, leaving a relief polymeric image. Several forms of 3D printing —including layer-by-layer stereolithography and two-photon absorption 3D photopolymerization —use photopolymerization. Multiphoton polymerization using single pulses have also been demonstrated for fabrication of complex structures using

378-407: Is prone to stick, such as fish and eggs. While all of these materials are still commonly used in professional kitchens, many modern materials have supplanted them in the consumer market. Nowadays, most frying pans are now made from metals such as aluminium or stainless steel . The materials and construction method used in modern frying pans vary greatly and some typical materials include: A coating

405-462: Is sometimes applied to the surface of the pan to make it non-stick . Frying pans made from bare cast iron or carbon steel can also gain non-stick properties through seasoning and use. A process for bonding Teflon to chemically roughened aluminium was patented in France by Marc Gregoire in 1954. In 1956 he formed a company to market non-stick cookware under the " Tefal " brand name. The durability of

432-404: Is to be incorporated in a later step such as a pan sauce. Since little or no residue can stick to the surface, the sauce will fail for lack of its primary flavouring agent. An electric frying pan or electric skillet incorporates an electric heating element into the frying pan itself and so can function independently off of a cooking stove . Accordingly, it has heat-insulated legs for standing on

459-592: The Fryingpan-Arkansas Project . [REDACTED] Media related to Fryingpan River at Wikimedia Commons This article related to a river in Colorado is a stub . You can help Misplaced Pages by expanding it . Frying pan A frying pan , frypan , or skillet is a flat-bottomed pan used for frying , searing , and browning foods. It is typically 20 to 30 cm (8 to 12 in) in diameter with relatively low sides that flare outwards,

486-453: The Old English panna . Before the introduction of the kitchen stove in the mid-19th century, a commonly used cast-iron cooking pan called a 'spider' had a handle and three legs used to stand up in the coals and ashes of the fire. Cooking pots and pans with legless, flat bottoms were designed when cooking stoves became popular; this period of the late 19th century saw the introduction of

513-655: The White River National Forest in the Sawatch Mountains along the western side of the continental divide . It flows westward along the county line between Pitkin and Eagle County . Below Meredith , it is dammed to form the Ruedi Reservoir . It joins the Roaring Fork below Basalt . A portion of the river's water is diverted to the east side of the continental divide for irrigation and drinking water via

540-456: The main classes of polymerization reaction mechanisms. The former is often easier to implement but requires precise control of stoichiometry. The latter more reliably affords high molecular-weight polymers, but only applies to certain monomers. In step-growth (or step) polymerization, pairs of reactants, of any lengths, combine at each step to form a longer polymer molecule. The average molar mass increases slowly. Long chains form only late in

567-401: The early coatings was initially poor, but improvements in manufacturing have made these products a kitchen standard. The surface is not as tough as metal and the use of metal utensils (e.g. spatulas ) can permanently mar the coating and degrade its non-stick property. For some cooking preparations a non-stick frying pan is inappropriate, especially for deglazing , where the residue of browning

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594-435: The flat cast-iron skillet. A versatile pan that combines the best of both the sauté pan and the frying pan has higher, sloping sides that are often slightly curved. This pan is called a sauteuse (literally a sauté pan in the female gender), an evasée (denoting a pan with sloping sides), or a fait-tout (literally "does everything"). Most professional kitchens have several of these utensils in varying sizes. A "rappie pan"

621-538: The initiation, propagation, and termination rates during chain polymerization. A related issue is temperature control, also called heat management , during these reactions, which are often highly exothermic. For example, for the polymerization of ethylene, 93.6 kJ of energy are released per mole of monomer. The manner in which polymerization is conducted is a highly evolved technology. Methods include emulsion polymerization , solution polymerization , suspension polymerization , and precipitation polymerization . Although

648-416: The polymer dispersity and molecular weight may be improved, these methods may introduce additional processing requirements to isolate the product from a solvent. Most photopolymerization reactions are chain-growth polymerizations which are initiated by the absorption of visible or ultraviolet light. Photopolymerization can also be a step-growth polymerization. The light may be absorbed either directly by

675-522: The reactant monomer ( direct photopolymerization), or else by a photosensitizer which absorbs the light and then transfers energy to the monomer. In general, only the initiation step differs from that of the ordinary thermal polymerization of the same monomer; subsequent propagation, termination, and chain-transfer steps are unchanged. In step-growth photopolymerization, absorption of light triggers an addition (or condensation) reaction between two comonomers that do not react without light. A propagation cycle

702-801: The reaction. Step-growth polymers are formed by independent reaction steps between functional groups of monomer units, usually containing heteroatoms such as nitrogen or oxygen. Most step-growth polymers are also classified as condensation polymers , since a small molecule such as water is lost when the polymer chain is lengthened. For example, polyester chains grow by reaction of alcohol and carboxylic acid groups to form ester links with loss of water. However, there are exceptions; for example polyurethanes are step-growth polymers formed from isocyanate and alcohol bifunctional monomers) without loss of water or other volatile molecules, and are classified as addition polymers rather than condensation polymers. Step-growth polymers increase in molecular weight at

729-570: The same monomer unit, whereas polymers that consist of more than one monomer unit are referred to as copolymers (or co-polymers). Other monomer units, such as formaldehyde hydrates or simple aldehydes, are able to polymerize themselves at quite low temperatures (ca. −80 °C) to form trimers ; molecules consisting of 3 monomer units, which can cyclize to form ring cyclic structures, or undergo further reactions to form tetramers , or 4 monomer-unit compounds. Such small polymers are referred to as oligomers . Generally, because formaldehyde

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