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Ethylene Propylene Rubber
Ethylene propylene rubber (EPR, sometimes called EPM referring to an ASTM standard) is a type of synthetic elastomer that is closely related to EPDM rubber. Since introduction in the 1960s, annual production has increased to 870,000 metric tons. http://www.azom.com/article.aspx?ArticleID=1822 ''Azom.com'', ''Ethylene Propylene Rubbers'', Thursday 19 April 2012http://www.iisrp.com/webpolymers/10epdmsep11.pdf ''iisrp'', ''Ethylene-Propylene Rubbers & Elastomers'', Thursday 19 April 2012 EPR is used in electrical cable insulation, and in many flexible rubber goods such as hoses or weatherstripping. Properties EPM is considered a valuable elastomer due to its useful chemical and physical properties; it is resistant to heat, oxidation, ozone and the weather (owing to its stable, saturated backbone) and it is also not susceptible to color loss. As a non-polar compound, EPM is an electrical resistor and it is insoluble in many polar solvents, both protic and aprotic. Amorphous forms ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Organic Compound
In chemistry, organic compounds are generally any chemical compounds that contain carbon-hydrogen or carbon-carbon bonds. Due to carbon's ability to catenate (form chains with other carbon atoms), millions of organic compounds are known. The study of the properties, reactions, and syntheses of organic compounds comprise the discipline known as organic chemistry. For historical reasons, a few classes of carbon-containing compounds (e.g., carbonate salts and cyanide salts), along with a few other exceptions (e.g., carbon dioxide, hydrogen cyanide), are not classified as organic compounds and are considered inorganic. Other than those just named, little consensus exists among chemists on precisely which carbon-containing compounds are excluded, making any rigorous definition of an organic compound elusive. Although organic compounds make up only a small percentage of Earth's crust, they are of central importance because all known life is based on organic compounds. Living t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Amorphous
In condensed matter physics and materials science, an amorphous solid (or non-crystalline solid, glassy solid) is a solid that lacks the long-range order that is characteristic of a crystal. Etymology The term comes from the Greek ''a'' ("without"), and ''morphé'' ("shape, form"). In some older articles and books, the term was used synonymously with glass. Today, "glassy solid" or "amorphous solid" is considered the overarching concept. Polymers are often amorphous. Structure Amorphous materials have an internal structure comprising interconnected structural blocks that can be similar to the basic structural units found in the corresponding crystalline phase of the same compound. Unlike crystalline materials, however, no long-range order exists. Localized order in amorphous materials can be categorized as short or medium range order. By convention, short range order extends only to the nearest neighbor shell, typically only 1-2 atomic spacings. Medium range order is then de ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Abrasion Resistance
Abrasion is the process of scuffing, scratching, wearing down, marring, or rubbing away. It can be intentionally imposed in a controlled process using an abrasive. Abrasion can be an undesirable effect of exposure to normal use or exposure to the elements. In stone shaping Ancient artists, working in stone, used abrasion to create sculptures. The artist selected dense stones like carbonite and emery and rubbed them consistently against comparatively softer stones like limestone and granite. The artist used different sizes and shapes of abrasives, or turned them in various ways as they rubbed, to create effects on the softer stone's surface. Water was continuously poured over the surface to carry away particles. Abrasive technique in stone shaping was a long, tedious process that, with patience, resulted in eternal works of art in stone. Models The Archard equation is a simple model used to describe sliding wear and is based on the theory of asperity contact. Q = \frac H whe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tear Resistance
Tear resistance (or tear strength) is a measure of how well a material can withstand the effects of tearing. It is a useful engineering measurement for a wide variety of materials by many different test methods. Discussion For example, with rubber, tear resistance measures how the test specimen resists the growth of any cuts when under tension, it is usually measured in kN/ m.Tear Resistance., , 15 June 2012 Tear resistance can be measured by the ''ASTM D 412'' method (the same used to measure tensile strength, modulus and elongation). ASTM D 624 can be used to measure the resistance to the formation of a tear (tear initiation) and the resistance to the expansion of a tear (tear propagation). Regardless of which of these two is being measured, the sample is held between two holders and a uniform pulling force applied until the aforementioned deformation occurs. Tear resistance is then calculated by dividing the force applied by the thickness of the material. Materials with low ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Compression Set
The compression set ( ASTM D395) of a material is the permanent deformation remaining after squashing it. In specific methods, temperatures and percent compression are specified. The term is normally applied to soft materials such as elastomers An elastomer is a polymer with viscoelasticity (i.e. both viscosity and elasticity) and with weak intermolecular forces, generally low Young's modulus and high failure strain compared with other materials. The term, a portmanteau of ''elastic p ... and foams. Compression is normally measured in two ways: ''compression set'' ''A'' and ''compression set'' ''B''. Compression Set A This has the formal name compression set under constant force in air. In ''compression set A'' a force of 1.8 kN is applied to the specimen for a set time at a set temperature. ''Compression set A'' is defined as the percentage of original specimen thickness after the specimen has been left in normal (uncompressed) conditions for 30 minutes. CA, the ''compressi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Deformation (mechanics)
In physics, deformation is the continuum mechanics transformation of a body from a ''reference'' configuration to a ''current'' configuration. A configuration is a set containing the positions of all particles of the body. A deformation can occur because of external loads, intrinsic activity (e.g. muscle contraction), body forces (such as gravity or electromagnetic forces), or changes in temperature, moisture content, or chemical reactions, etc. Strain is related to deformation in terms of ''relative'' displacement of particles in the body that excludes rigid-body motions. Different equivalent choices may be made for the expression of a strain field depending on whether it is defined with respect to the initial or the final configuration of the body and on whether the metric tensor or its dual is considered. In a continuous body, a deformation field results from a stress field due to applied forces or because of some changes in the temperature field of the body. The rel ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tensile Strength
Ultimate tensile strength (UTS), often shortened to tensile strength (TS), ultimate strength, or F_\text within equations, is the maximum stress that a material can withstand while being stretched or pulled before breaking. In brittle materials the ultimate tensile strength is close to the yield point, whereas in ductile materials the ultimate tensile strength can be higher. The ultimate tensile strength is usually found by performing a tensile test and recording the engineering stress versus strain. The highest point of the stress–strain curve is the ultimate tensile strength and has units of stress. The equivalent point for the case of compression, instead of tension, is called the compressive strength. Tensile strengths are rarely of any consequence in the design of ductile members, but they are important with brittle members. They are tabulated for common materials such as alloys, composite materials, ceramics, plastics, and wood. Definition The ultimate tensile streng ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Shore Durometer
The Shore durometer is a device for measuring the hardness of a material, typically of polymers. Higher numbers on the scale indicate a greater resistance to indentation and thus harder materials. Lower numbers indicate less resistance and softer materials. The term is also used to describe a material's rating on the scale, as in an object having a "'Shore durometer' of 90." The scale was defined by Albert Ferdinand Shore, who developed a suitable device to measure hardness in the 1920s. It was neither the first hardness tester nor the first to be called a ''durometer'' ( ISV '' duro-'' and '' -meter''; attested since the 19th century), but today that name usually refers to Shore hardness; other devices use other measures, which return corresponding results, such as for Rockwell hardness. Durometer scales There are several scales of durometer, used for materials with different properties. The two most common scales, using slightly different measurement systems, are the ASTM ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hardness
In materials science, hardness (antonym: softness) is a measure of the resistance to localized plastic deformation induced by either mechanical indentation or abrasion. In general, different materials differ in their hardness; for example hard metals such as titanium and beryllium are harder than soft metals such as sodium and metallic tin, or wood and common plastics. Macroscopic hardness is generally characterized by strong intermolecular bonds, but the behavior of solid materials under force is complex; therefore, hardness can be measured in different ways, such as scratch hardness, indentation hardness, and rebound hardness. Hardness is dependent on ductility, elastic stiffness, plasticity, strain, strength, toughness, viscoelasticity, and viscosity. Common examples of hard matter are ceramics, concrete, certain metals, and superhard materials, which can be contrasted with soft matter. Measuring hardness There are three main types of hardness measurements: ''scratch' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Specific Gravity
Relative density, or specific gravity, is the ratio of the density (mass of a unit volume) of a substance to the density of a given reference material. Specific gravity for liquids is nearly always measured with respect to water (molecule), water at its densest (at ); for gases, the reference is air at room temperature (). The term "relative density" (often abbreviated r.d. or RD) is often preferred in scientific usage, whereas the term "specific gravity" is deprecation, deprecated. If a substance's relative density is less than 1 then it is less dense than the reference; if greater than 1 then it is denser than the reference. If the relative density is exactly 1 then the densities are equal; that is, equal volumes of the two substances have the same mass. If the reference material is water, then a substance with a relative density (or specific gravity) less than 1 will float in water. For example, an ice cube, with a relative density of about 0.91, will float. A substance wi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mooney Viscosity
A Mooney viscometer is an instrument used for measuring the ''Mooney viscosity'' of rubbers.ACS Rubber Division Science & Technology Awards Invented by Melvin Mooney
Melvin Mooney (1893–1968) was an American physicist and rheologist.
Life
Mooney was born in Kansas City, Missouri.J. H. Dillon (1948) J. Colloid Sci. 4 (3) 187-8 "Introduction of Melvin Mooney as E. C. Bingham Medallist" He achieved an A. ... , it contains a rotating spindle and heated dies, the substanc ...
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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 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 with the network creating other c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
