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Plastisol
A plastisol is a colloidal dispersion of small polymer particles, usually polyvinyl chloride (PVC), in a liquid plasticizer. When heated to around , the plastic particles absorb the plasticizer, causing them to swell and fuse together forming a viscous gel. Once this is cooled to below it becomes a flexible, permanently plasticized solid product.Schey, J.A. "Introduction to Manufacturing Processes", ''The McGraw-Hill Companies'' (3rd Edition, 2000). Page 555. This process is called ' curing'. Commercial plastisols have good compatibility with pigments and dyes allowing for brightly coloured finished products. Before being cured they flow as a liquid, and can easily be poured into a mould, used for dip-coatings or as a textile ink for screen-printing. Once cured it has a flexible, rubbery consistency. They are commonly used for coatings, particularly in outdoor applications (roofs, furniture) or grips for tools. Mattel Toys used plastisols for years in creating such things as Ba ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Screen-printing
Screen printing is a printing technique where a mesh is used to transfer ink (or dye) onto a Substrate (printing), substrate, except in areas made impermeable to the ink by a blocking stencil. A blade or squeegee is moved across the screen in a "flood stroke" to fill the open mesh apertures with ink, and a reverse stroke then causes the screen to touch the substrate momentarily along a line of contact. This causes the ink to wet the substrate and be pulled out of the mesh apertures as the screen springs back after the blade has passed. One colour is printed at a time, so several screens can be used to produce a multi-coloured image or design. Traditionally, silk was used in the process. Currently, synthetic threads are commonly used. The most popular mesh in general use is made of polyester. There are special-use mesh materials of nylon and stainless steel available to the screen-printer. There are also different types of mesh size which will determine the outcome and look o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Polyvinyl Chloride
Polyvinyl chloride (alternatively: poly(vinyl chloride), colloquial: vinyl or polyvinyl; abbreviated: PVC) is the world's third-most widely produced synthetic polymer of plastic (after polyethylene and polypropylene). About 40 million tons of PVC are produced each year. PVC comes in rigid (sometimes abbreviated as RPVC) and flexible forms. Rigid PVC is used in construction for pipes, doors and windows. It is also used in making plastic bottles, packaging, and bank or membership cards. Adding plasticizers makes PVC softer and more flexible. It is used in plumbing, electrical cable insulation, flooring, signage, phonograph records, inflatable products, and in rubber substitutes. With cotton or linen, it is used in the production of canvas. Polyvinyl chloride is a white, brittle solid. It is soluble in ketones, chlorinated solvents, dimethylformamide, THF and DMAc. Discovery PVC was synthesized in 1872 by German chemist Eugen Baumann after extended investigation and experimenta ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Solid Rocket Motor
A solid-propellant rocket or solid rocket is a rocket with a rocket engine that uses solid propellants (fuel/oxidizer). The earliest rockets were solid-fuel rockets powered by gunpowder. The inception of gunpowder rockets in warfare can be credited to the ancient Chinese, and in the 13th century, the Mongols played a pivotal role in facilitating their westward adoption. All rockets used some form of solid or powdered propellant until the 20th century, when liquid-propellant rockets offered more efficient and controllable alternatives. Because of their simplicity and reliability, solid rockets are still used today in military armaments worldwide, model rockets, solid rocket boosters and on larger applications. Since solid-fuel rockets can remain in storage for an extended period without much propellant degradation, and since they almost always launch reliably, they have been frequently used in military applications such as missiles. The lower performance of solid propellants (a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Curing (chemistry)
Curing is a chemical process employed in polymer chemistry and process engineering that produces the toughening or hardening of a polymer material by cross-linking of polymer chains. Even if it is strongly associated with the production of thermosetting polymers, the term "curing" can be used for all the processes where a solid product is obtained from a liquid solution, such as with PVC plastisols. Curing process During the curing process, single monomers and oligomers, mixed with or without a curing agent, react to form a tridimensional polymeric network. In the very first part of the reaction Branching (polymer chemistry), branches of molecules with various architectures are formed, and their molecular weight increases in time with the extent of the reaction until the network size is equal to the size of the system. The system has lost its solubility and its viscosity tends to infinite. The remaining molecules start to coexist with the macroscopic network until they react wit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Copper Chromite
Copper chromite often refers to inorganic compounds with the formula . They are black solids. is a well-defined material. The other copper chromite often is described as . It is used to catalyze reactions in organic chemistry. History Copper chromite was first described in 1908. The catalyst was further developed by Homer Burton Adkins and Wilbur Arthur Lazier, partly based on interrogation of German chemists after World War II in relation to the Fischer–Tropsch process. For this reason it is sometimes referred to as the Adkins catalyst or the Lazier catalyst. Adkins was the first to incorporate barium into the structure, which prevents the catalyst from being reduced to an inactive form during hydrogenation reactions. Chemical structures The stoichiometry of the Laziar or Adkins catalyst is not well defined, thus the structure of their material is not defined either. The oxidation states for the constituent metals in Cu2Cr2O4 are Cu(II) and Cr(III). A variety of compo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oxidizer
An oxidizing agent (also known as an oxidant, oxidizer, electron recipient, or electron acceptor) is a substance in a redox chemical reaction that gains or " accepts"/"receives" an electron from a (called the , , or ''electron donor''). In other words, an oxidizer is any substance that oxidizes another substance. The oxidation state, which describes the degree of loss of electrons, of the oxidizer decreases while that of the reductant increases; this is expressed by saying that oxidizers "undergo reduction" and "are reduced" while reducers "undergo oxidation" and "are oxidized". Common oxidizing agents are oxygen, hydrogen peroxide, and the halogens. In one sense, an oxidizing agent is a chemical species that undergoes a chemical reaction in which it gains one or more electrons. In that sense, it is one component in an oxidation–reduction (redox) reaction. In the second sense, an oxidizing agent is a chemical species that transfers electronegative atoms, usually oxygen, to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ammonium Perchlorate
Ammonium perchlorate ("AP") is an inorganic compound with the formula . It is a colorless or white solid that is soluble in water. It is a powerful oxidizer. Combined with a fuel, it can be used as a rocket propellant called ammonium perchlorate composite propellant. Its instability has involved it in accidents such as the PEPCON disaster. Production Ammonium perchlorate (AP) is produced by reaction between ammonia and perchloric acid. This process is the main outlet for the industrial production of perchloric acid. The salt also can be produced by salt metathesis reaction of ammonium salts with sodium perchlorate. This process exploits the relatively low solubility of NH4ClO4, which is about 10% of that for sodium perchlorate.Helmut Vogt, Jan Balej, John E. Bennett, Peter Wintzer, Saeed Akbar Sheikh, Patrizio Gallone "Chlorine Oxides and Chlorine Oxygen Acids" in Ullmann's Encyclopedia of Industrial Chemistry 2002, Wiley-VCH. AP crystallises as colorless rhombohedra. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aluminium
Aluminium (or aluminum in North American English) is a chemical element; it has chemical symbol, symbol Al and atomic number 13. It has a density lower than that of other common metals, about one-third that of steel. Aluminium has a great affinity towards oxygen, passivation (chemistry), forming a protective layer of aluminium oxide, oxide on the surface when exposed to air. It visually resembles silver, both in its color and in its great ability to reflect light. It is soft, magnetism, nonmagnetic, and ductility, ductile. It has one stable isotope, 27Al, which is highly abundant, making aluminium the abundance of the chemical elements, 12th-most abundant element in the universe. The radioactive decay, radioactivity of aluminium-26, 26Al leads to it being used in radiometric dating. Chemically, aluminium is a post-transition metal in the boron group; as is common for the group, aluminium forms compounds primarily in the +3 oxidation state. The aluminium cation Al3+ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Magnesium
Magnesium is a chemical element; it has Symbol (chemistry), symbol Mg and atomic number 12. It is a shiny gray metal having a low density, low melting point and high chemical reactivity. Like the other alkaline earth metals (group 2 of the periodic table), it occurs naturally only in combination with other elements and almost always has an oxidation state of +2. It reacts readily with air to form a thin Passivation (chemistry), passivation coating of magnesium oxide that inhibits further corrosion of the metal. The free metal burns with a brilliant-white light. The metal is obtained mainly by electrolysis of magnesium Salt (chemistry), salts obtained from brine. It is less dense than aluminium and is used primarily as a component in strong and lightweight magnesium alloy, alloys that contain aluminium. In the cosmos, magnesium is produced in large, aging stars by the sequential addition of three Helium nucleus, helium nuclei to a carbon nucleus. When such stars explo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oxamide
Oxamide is the organic compound with the formula . This white crystalline solid is soluble in ethanol, slightly soluble in water and insoluble in diethyl ether. Oxamide is the diamide derived from oxalic acid, and the hydrate of cyanogen. Preparation Oxamide is produced from hydrogen cyanide, which is oxidized to cyanogen, which is then hydrolyzed.. It can also be prepared from formamide by glow-discharge electrolysis. Application The main application is as a substitute for urea in fertilizers. Oxamide hydrolyzes (releases ammonia) very slowly, which is sometimes preferred vs the quick release by urea. It is used as a stabilizer for nitrocellulose preparations. It also finds use in APCP rocket motors as a high performance burn rate suppressant. The use of oxamide in concentrations of 1-3 wt% has shown to slow the linear burn rate while having minimal impact on propellant specific impulse. ''N'',''N'-''substituted oxamides are supporting ligands for the copper-catalyzed ami ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dibutyl Sebacate
Dibutyl sebacate (DBS) is an organic chemical, a di butyl ester of sebacic acid. Its main use is as a plasticizer in production of plastics, namely cellulose acetate butyrate, cellulose acetate propionate, ethyl cellulose, polyvinyl butyral, polyvinyl chloride, polystyrene, and many synthetic rubbers (especially nitrile rubber and neoprene) and other plastics. It can be used for plastics in use in the food packaging industry, in plastics used for medical devices, and for pharmaceutical applications, e.g. as a plasticizer for film coating of tablets, beads, and granules.chemicalland21.co''Dibutyl Sebacate'' It is also used as a lubricant in shaving lotions, and a flavoring additive in non-alcoholic beverages, ice cream, ices, candy Candy, alternatively called sweets or lollies, is a Confectionery, confection that features sugar as a principal ingredient. The category, also called ''sugar confectionery'', encompasses any sweet confection, including chocolate, ch ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
