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Flame Treatment
Flame treatment is the application of a gas flame to the surface of a material to improve adhesion. Polyolefins, especially polyethylene and polypropylene bond poorly, because they consist of long non- polar molecules. Without special treatment, adhesives, ink, and other coatings cannot be applied to these materials. By rapidly applying intense heat to a surface, molecular chains are broken and polar functional groups are added. Flame treatment also burns off dust, fibers, oils, and other surface contaminants. Process Flame treatment is a method where exothermic reactions between oxygen and fuel gas create thermally activated radical atoms and molecules, such as atomic oxygen (O), hydroxyl (OH), imidogen (NH), Nitric oxide (NO), and cyanide (CN). The most used gases in flame treatment are propane (C3H8), natural gas or methane (CH4), and butane (C4H10). These gases burn with atmospheric oxygen, producing water and carbon dioxide. The flame has three zones; the precombustion zo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Adhesion
Adhesion is the tendency of dissimilar particles or interface (matter), surfaces to cling to one another. (Cohesion (chemistry), Cohesion refers to the tendency of similar or identical particles and surfaces to cling to one another.) The forces that cause adhesion and cohesion can be divided into several types. The intermolecular forces responsible for the function of various kinds of stickers and sticky tape fall into the categories of chemical adhesion, dispersive adhesion, and diffusive adhesion. In addition to the cumulative magnitudes of these intermolecular forces, there are also certain emergent mechanical effects. Surface energy Surface energy is conventionally defined as the work (physics), work that is required to build an area of a particular surface. Another way to view the surface energy is to relate it to the work required to cleave a bulk sample, creating two surfaces. If the new surfaces are identical, the surface energy γ of each surface is equal to h ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oxidizing Agent
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, t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Surface Finishing
Surface finishing is a broad range of industrial processes that alter the surface of a manufactured item to achieve a certain property. Finishing processes may be employed to: improve product appearance, adhesion or wettability, solderability, corrosion resistance, tarnish resistance, the chemical resistance, the wear resistance, hardness, modify electrical conductivity, remove burrs and other surface flaws, and control the surface friction.. In limited cases some of these techniques can be used to restore original dimensions to salvage or repair an item. An unfinished surface is often called '' mill finish''. These processes can improve the durability, performance and even the appearance of the surface being finished. Surface finishing is often one of the final steps taken when working metal and is essential for guaranteeing that metal components meet the requirements of the necessary finish. Surface finishing processes can be categorized by how they affect the workpiece: ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stone Flaming
Stone flaming or thermaling is the application of high temperature to the surface of stone to make it look like natural weathering. The sudden application of a torch to the surface of stone causes the surface layer to expand and flake off, exposing rough stone. Flaming works well on granite, because granite is made up of minerals with differing heat expansion rates. Process After removing a rock from a quarry, the rock is sliced into multiple flat slabs using a diamond gang saw. The saw leaves flat surfaces with circular marks. Flaming is done by wetting, and then running an oxygen-acetylene or oxygen-propane torch over the surface. As shown in both pictures, the torch is usually held at a 45-degree angle to the stone, so that released glowing sand grains are blown away in a harmless direction. Alternatives Alternative techniques for creating a rough surface on sawed stone include: * bush hammering * sandblasting Sandblasting, sometimes known as abrasive bla ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Polymeric Surface
Polymeric materials have widespread application due to their versatile characteristics, cost-effectiveness, and highly tailored production. The science of polymer synthesis allows for excellent control over the properties of a bulk polymer sample. However, surface interactions of polymer substrates are an essential area of study in biotechnology, nanotechnology, and in all forms of coating applications. In these cases, the surface characteristics of the polymer and material, and the resulting forces between them largely determine its utility and reliability. In biomedical applications for example, the bodily response to foreign material, and thus biocompatibility, is governed by surface interactions. In addition, surface science is integral part of the formulation, manufacturing, and application of coatings. __TOC__ Chemical methods A polymeric material can be functionalized by the addition of small moieties, oligomers, and even other polymers (grafting copolymers) ont ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Corona Treatment
Corona treatment (sometimes referred to as air plasma) is a surface modification technique that uses a low temperature corona discharge plasma to impart changes in the properties of a surface. The corona plasma is generated by the application of high voltage to an electrode that has a sharp tip. The plasma forms at the tip. A linear array of electrodes is often used to create a curtain of corona plasma. Materials such as plastics, cloth, or paper may be passed through the corona plasma curtain in order to change the surface energy of the material. All materials have an inherent surface energy. Surface treatment systems are available for virtually any surface format including dimensional objects, sheets and roll goods that are handled in a web format. Corona treatment is a widely used surface treatment method in the plastic film, extrusion, and converting industries. History The corona treatment was invented by the Danish engineer Verner Eisby in 1951. Eisby had been asked b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Plasma Activation
Plasma activation (or plasma functionalization) is a method of surface functionalization, surface modification employing plasma processing, which improves surface adhesion properties of many materials including metals, glass, ceramics, a broad range of polymers and textiles and even natural materials such as wood and seeds. Plasma functionalization also refers to the introduction of functional groups on the surface of exposed materials. It is widely used in industrial processes to prepare surfaces for bonding, gluing, coating and painting. Plasma processing achieves this effect through a combination of reduction of metal oxides, ultra-fine plasma cleaning , surface cleaning from organic contaminants, modification of the surface topography and deposition of functional chemical groups. Importantly, the plasma activation can be performed at atmospheric pressure using air or typical industrial gases including hydrogen, nitrogen and oxygen. Thus, the surface functionalization is achieved ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chemistry Of Pressure-sensitive Adhesives
The chemistry of pressure-sensitive adhesives describes the chemical science associated with pressure-sensitive adhesives (PSA). PSA tapes and labels have become an important part of everyday life. These rely on adhesive material affixed to a backing such as paper or plastic film. Because of the inherent tackiness of the adhesive material and low surface energy, these tapes can be placed onto a variety of substrates when light pressure is applied, including paper, wood, metals, and ceramics. The design of tapes requires a balance of the need for long service life and adaptation to a variety of environmental and human effects, including temperature, UV exposure, mechanical wear, contamination of the substrate surface, and adhesive degradation.Werner Karmann and Andreas B. Kummer "Tapes, Adhesive" in Ullmann's Encyclopedia of Industrial Chemistry, Wiley-VCH, Weinheim, 2000. Composition A typical PSA tape consists of a pressure-sensitive adhesive (the sticky part of the tape) ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chemical Species
Chemical species are a specific form of chemical substance or chemically identical molecular entities that have the same molecular energy level at a specified timescale. These entities are classified through bonding types and relative abundance of isotopes. Types of chemical species can be classified based on the type of molecular entity and can be either an atomic, molecular, ionic or radical species. Classification Generally, a chemical species is defined as a chemical identity that has the same set of molecular energy levels in a defined timescale (i.e. an experiment). These energy levels determine the way the chemical species will interact with others through properties such as bonding or isotopic compositions. The chemical species can be an atom, molecule, ion, or radical, with a specific chemical name and chemical formula. In supramolecular chemistry, chemical species are structures created by forming or breaking bonds between molecules, such as hydrogen bonding, dipole ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Butane
Butane () is an alkane with the formula C4H10. Butane exists as two isomers, ''n''-butane with connectivity and iso-butane with the formula . Both isomers are highly flammable, colorless, easily liquefied gases that quickly vaporize at room temperature and pressure. Butanes are a trace components of natural gases (NG gases). The other hydrocarbons in NG include propane, ethane, and especially methane, which are more abundant. Liquefied petroleum gas is a mixture of propane and some butanes. The name butane comes from the root but- (from butyric acid, named after the Greek word for butter) and the suffix -ane (for organic compounds). History The first synthesis of butane was accidentally achieved by British chemist Edward Frankland in 1849 from ethyl iodide and zinc, but he had not realized that the ethyl radical dimerized and misidentified the substance. It was discovered in crude petroleum in 1864 by Edmund Ronalds, who was the first to describe its proper ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Materials Today
''Materials Today'' is a monthly peer-reviewed scientific journal, website, and journal family. The parent journal was established in 1998 and covers all aspects of materials science. It is published by Elsevier and the editors-in-chief are Jun Lou (Rice University) and Gleb Yushin (Georgia Institute of Technology). The journal principally publishes invited review articles, but other formats are also included, such as primary research articles, news items, commentaries, and opinion pieces on subjects of interest to the field. The website publishes news, educational webinars, podcasts, and blogs, as well as a jobs and events board. According to the ''Journal Citation Reports'', the journal has a 2020 impact factor The impact factor (IF) or journal impact factor (JIF) of an academic journal is a type of journal ranking. Journals with higher impact factor values are considered more prestigious or important within their field. The Impact Factor of a journa ... of 31.041. The jour ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Methane
Methane ( , ) is a chemical compound with the chemical formula (one carbon atom bonded to four hydrogen atoms). It is a group-14 hydride, the simplest alkane, and the main constituent of natural gas. The abundance of methane on Earth makes it an economically attractive fuel, although capturing and storing it is difficult because it is a gas at standard temperature and pressure. In the Earth's atmosphere methane is transparent to visible light but absorbs infrared radiation, acting as a greenhouse gas. Methane is an Organic chemistry, organic Organic compound, compound, and among the simplest of organic compounds. Methane is also a hydrocarbon. Naturally occurring methane is found both below ground and under the seafloor and is formed by both geological and biological processes. The largest reservoir of methane is under the seafloor in the form of methane clathrates. When methane reaches the surface and the Atmosphere of Earth, atmosphere, it is known as atmospheric methane. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
