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Polymer Solution
Polymer solutions are solutions containing dissolved polymers. These may be (e.g. in ), or solid solutions (e.g. a substance which has been plasticized). The introduction into the polymer of small amounts of a solvent (plasticizer) reduces the temperature of glass transition, the yield temperature, and the viscosity of a melt. An understanding of the thermodynamics of a polymer solution is critical to prediction of its behavior in manufacturing processes — for example, its shrinkage or expansion in injection molding processes, or whether pigments and solvents will mix evenly with a polymer in the manufacture of paints and coatings. A recent theory on the viscosity of polymer solutions gives a physical explanation for various well-known empirical relations and numerical values including the Huggins constant, but reveals also novel simple concentration and molar mass dependence. Applications Polymer solutions are used in producing fibers, films, glues, lacquers, paints, and oth ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Solution (chemistry)
In chemistry, a solution is defined by IUPAC as "A liquid or solid phase containing more than one substance, when for convenience one (or more) substance, which is called the solvent, is treated differently from the other substances, which are called solutes. When, as is often but not necessarily the case, the sum of the mole fractions of solutes is small compared with unity, the solution is called a dilute solution. A superscript attached to the ∞ symbol for a property of a solution denotes the property in the limit of infinite dilution." One important parameter of a solution is the concentration, which is a measure of the amount of solute in a given amount of solution or solvent. The term " aqueous solution" is used when one of the solvents is water. Types ''Homogeneous'' means that the components of the mixture form a single phase. ''Heterogeneous'' means that the components of the mixture are of different phase. The properties of the mixture (such as concentration, temp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
American Institute Of Chemical Engineers
The American Institute of Chemical Engineers (AIChE) is a professional organization for chemical engineers. AIChE was established in 1908 to distinguish chemical engineers as professionals independent of chemists and mechanical engineers. Currently, AIChE has over 60,000 members from over 110 countriesAbout the AIChE, Overview (from the AIChE website) or 40,000 members from 93 countries. by 2024 (sources vary). There are over 350 active student chapters at universities worldwide. Student chapters aim to provide networking opportunities in academia and industry as well as increase student involvement locally and nationally. History of formation :''This section consists of excerpts from a historical pamphlet written for the Silver Anniversary of the AICHE in 1932.''[...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Solution Polymerization
Solution polymerization is a method of industrial polymerization. In this procedure, a monomer is dissolved in a non-reactive solvent that contains a catalyst or initiator. The reaction results in a polymer which is also soluble in the chosen solvent. Heat released by the reaction is absorbed by the solvent, reducing the reaction rate. Moreover, the viscosity of the reaction mixture is reduced, preventing autoacceleration at high monomer concentrations. A decrease in viscosity of the reaction mixture by dilution also aids heat transfer, one of the major issues connected with polymer production, since most polymerizations are exothermic reactions. Once the desired conversion is reached, excess solvent must be removed to obtain the pure polymer. Accordingly, solution polymerization is primarily used in applications where the presence of a solvent is desired anyway, as is the case for varnish and adhesives. Another application of polymer solutions includes the manufacture of fibers b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Colloid
A colloid is a mixture in which one substance consisting of microscopically dispersed insoluble particles is suspended throughout another substance. Some definitions specify that the particles must be dispersed in a liquid, while others extend the definition to include substances like aerosols and gels. The term colloidal suspension refers unambiguously to the overall mixture (although a narrower sense of the word '' suspension'' is distinguished from colloids by larger particle size). A colloid has a dispersed phase (the suspended particles) and a continuous phase (the medium of suspension). The dispersed phase particles have a diameter of approximately 1 nanometre to 1 micrometre. Some colloids are translucent because of the Tyndall effect, which is the scattering of light by particles in the colloid. Other colloids may be opaque or have a slight color. Colloidal suspensions are the subject of interface and colloid science. This field of study began in 1845 by Franc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Flory–Huggins Solution Theory
Flory–Huggins solution theory is a lattice model (physics), lattice model of the thermodynamics of polymer solutions which takes account of the great dissimilarity in molecule, molecular sizes in adapting the usual expression (mathematics), expression for the entropy of mixing. The result is an equation for the Gibbs free energy change \Delta G_ for mixing a polymer with a solvent. Although it makes simplifying assumptions, it generates useful results for interpreting experiments. Theory The thermodynamic potentials, thermodynamic equation for the Gibbs energy change accompanying mixing at constant temperature and (external) pressure is : \Delta G_ = \Delta H_ - T\Delta S_ A change, denoted by \Delta, is the number, value of a Variable (mathematics), variable for a Solution (chemistry), solution or mixture minus the values for the pure Component (thermodynamics), components considered separately. The objective is to find explicit formulas for \Delta H_ and \Delta S_, the en ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hydraulic Fracturing
Fracking (also known as hydraulic fracturing, fracing, hydrofracturing, or hydrofracking) is a well stimulation technique involving the fracturing of Formation (geology), formations in bedrock by a pressurized liquid. The process involves the high-pressure injection of "fracking fluid" (primarily water, containing sand or other hydraulic fracturing proppants, proppants suspended with the aid of thickening agents) into a wellbore to create cracks in the deep-rock formations through which natural gas, petroleum, and brine will flow more freely. When the hydraulic pressure is removed from the well, small grains of hydraulic fracturing proppants (either sand or aluminium oxide) hold the fractures open. Fracking, using either hydraulic pressure or acid, is the most common method for well stimulation. Well stimulation techniques help create pathways for oil, gas or water to flow more easily, ultimately increasing the overall production of the well. Both methods of fracking are classe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Guar
The guar (from : gvār) or cluster bean, with the botanical name ''Cyamopsis tetragonoloba'', is an annual plant, annual legume and the source of guar gum. It is also known as gavar, gawar, or guvar bean. The genus name ''Cyamopsis'' means ''bean-like'' (from : kýamos "bean" + : ópsis "view'). The specific name is from meaning ''four-lobed''. The origin of ''Cyamopsis tetragonoloba'' is unknown, since it has never been found in the wild.Whistler R. L. and Hymowitz T. 1979. Guar: agronomy, production, industrial use and nutrition. Purdue University Press, West Lafayette It is assumed to have developed from the African species ''Cyamopsis senegalensis''. It was further domesticated in South Asia, where it has been cultivated for centuries. Guar grows well in semiarid areas, but frequent rainfall is necessary. This legume is a valuable plant in a crop rotation cycle, as it lives in symbiosis with nitrogen-fixing bacteria.Undersander D. J., Putnam D. H., Kaminski A. R., Dol ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Light-emitting Diode
A light-emitting diode (LED) is a semiconductor device that emits light when current flows through it. Electrons in the semiconductor recombine with electron holes, releasing energy in the form of photons. The color of the light (corresponding to the energy of the photons) is determined by the energy required for electrons to cross the band gap of the semiconductor. White light is obtained by using multiple semiconductors or a layer of light-emitting phosphor on the semiconductor device. Appearing as practical electronic components in 1962, the earliest LEDs emitted low-intensity infrared (IR) light. Infrared LEDs are used in remote-control circuits, such as those used with a wide variety of consumer electronics. The first visible-light LEDs were of low intensity and limited to red. Early LEDs were often used as indicator lamps, replacing small incandescent bulbs, and in seven-segment displays. Later developments produced LEDs available in visible, ultraviolet (U ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Polymer Material
Polymer engineering is generally an engineering field that designs, analyses, and modifies polymer materials. Polymer engineering covers aspects of the petrochemical industry, polymerization, structure and characterization of polymers, properties of polymers, compounding and processing of polymers and description of major polymers, structure property relations and applications. History The word “polymer” was introduced by the Swedish chemist J. J. Berzelius. He considered, for example, benzene (C6H6) to be a polymer of ethyne (C2H2). Later, this definition underwent a subtle modification. The history of human use of polymers has been long since the mid-19th century, when it entered the chemical modification of natural polymers. In 1839, Charles Goodyear found a critical advance in the research of rubber vulcanization, which has turned natural rubber into a practical engineering material. In 1870, J. W. Hyatt uses camphor to plasticize nitrocellulose to make nitrocellulose pl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Paint
Paint is a material or mixture that, when applied to a solid material and allowed to dry, adds a film-like layer. As art, this is used to create an image or images known as a painting. Paint can be made in many colors and types. Most paints are either oil-based or water-based, and each has distinct characteristics. Primitive forms of paint were used tens of thousands of years ago in cave paintings. Clean-up solvents are also different for water-based paint than oil-based paint. Water-based paints and oil-based paints will cure differently based on the outside ambient temperature of the object being painted (such as a house). History Paint was used in some of the earliest known human artworks. Some cave paintings drawn with red or yellow ochre, hematite, manganese oxide, and charcoal may have been made by early ''Homo sapiens'' as long as 40,000 years ago. Paint may be even older. In 2003 and 2004, South African archeologists reported finds in Blombos Cave of a 100,000-y ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lacquer
Lacquer is a type of hard and usually shiny coating or finish applied to materials such as wood or metal. It is most often made from resin extracted from trees and waxes and has been in use since antiquity. Asian lacquerware, which may be called "true lacquer", are objects coated with the treated, dyed and dried sap of ''Toxicodendron vernicifluum'' or related trees, applied in several coats to a base that is usually wood. This dries to a very hard and smooth surface layer which is durable, waterproof, and attractive in feel and look. Asian lacquer is sometimes painted with pictures, inlaid with shell and other materials, or carved lacquer, carved, as well as maki-e, dusted with gold and given other further decorative treatments. In modern techniques, lacquer means a range of clear or pigmented coatings that dry by solvent evaporation to produce a hard, durable finish. The finish can be of any sheen level from ultra wikt:matte, matte to high Gloss (material appearance), glos ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Glue
Adhesive, also known as glue, cement, mucilage, or paste, is any non-metallic substance applied to one or both surfaces of two separate items that binds them together and resists their separation. The use of adhesives offers certain advantages over other binding techniques such as sewing, mechanical fastenings, and welding. These include the ability to bind different materials together, the more efficient distribution of stress across a joint, the cost-effectiveness of an easily mechanized process, and greater flexibility in design. Disadvantages of adhesive use include decreased stability at high temperatures, relative weakness in bonding large objects with a small bonding surface area, and greater difficulty in separating objects during testing. Adhesives are typically organized by the method of adhesion followed by ''reactive'' or ''non-reactive'', a term which refers to whether the adhesive chemically reacts in order to harden. Alternatively, they can be organized eithe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
