部分材料类专业术语的英文解释.doc

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1、Adsorb or AdsorptionThe adhesion of a layer of molecules (gas or liquid) to the surface of a solid.Adsorb is not the same as absorb, an action in which molecules are taken into pores in the surface of a solid. Fumed silica is non-porous.AgglomeratesA collection of smaller particles held together by

2、weak forces, such as mechanical entanglement. For example, individual tree branches trimmed off a tree and thrown into a pile will form an agglomerate.The agglomerates formed in the fumed silica process are generally easy to disperse and can be broken down by proper dispersion equipment. The typical

3、 mean agglomerate size of Cabots fumed silicas is 25 to 30 microns.AggregatesA collection of smaller particles that have been permanently joined together.In fumed silica, the primary particles have sintered together to form an aggregate, which is extremely strong. The typical mean aggregate size of

4、Cabots fumed silica is 0.2 to 0.3 microns. The aggregate is the smallest particle to which fumed silica can be dispersed.AmorphousNon-crystalline, not having a definite repeating structure.Glass is an example of amorphous silica. Examples of crystalline forms of silica are quartz, cristobalite and t

5、ridymite. Amorphous silica is very stable and it is impossible for it to crystallize, except after exposure to very high temperatures and pressure for extremely long periods of time.Anti-blockingThe prevention of fusion or sticking between two surfaces.Fumed silica prevents blocking by providing mic

6、ro-roughness to the surface, thus preventing actual contact between the two surfaces. Applications for this are in coatings, plastic films and continuous metal casters.Anti-cakingThe ability to prevent the formation of clumps in a powder.Fumed silica prevents caking or acts as an anti-caking agent i

7、n dry powders such as those used in cosmetics, food, nutraceuticals and pharmaceuticals.Anti-mistingThe ability to prevent misting.In high speed printing processes, such as gravure and letterpress, small droplets of ink can be thrown from the rolls by centrifugal force, developing a mist. This mist

8、of ink causes cleaning problems, and it can also cause dirty print. Fumed silica will reduce misting in inks by providing thixotropic behavior.Anti-sagThe ability to support a certain amount of material against the pull of gravity and not have the material flow.Fumed silica imparts sag resistance to

9、 liquids, which is important in applications such as coatings, sealants, adhesives and reinforced plastics.Anti-settlingPrevention of an accumulation of particles on the bottom a container from a dispersion of particles in liquid.Fumed silicas prevent settling by forming a network in liquid systems.

10、 This network can support most pigments and prevent them from being pulled to the bottom of the container by gravity. Anti-settling is important in paint, ink and cosmetic applications.ASTMAmerican Society for Testing and MaterialsThis organization sets the standards of measurement for many industri

11、es in the USA. ASTM measurement tests are categorized by industry and each is assigned a number.AtomizationTo be separated into very fine particles (solids) or a very fine spray (liquids).When paint is sprayed, the thixotropic action of fumed silica allows the viscosity to fall. This allows the liqu

12、id to be atomized easily into small droplets. These small droplets are easily conveyed to the substrate and can form a smooth continuous film.Bulk densityThe quantity or mass of a substance per unit volume.Fumed silicas are very light and fluffy and have bulk densities of 2 to 2.5 pounds per cubic f

13、oot (35 to 48 g/l), accounting for the large 10-pound bags and the dusty nature of fumed silicas.Calcine/CalciningTo heat a powder to a high temperature, but not hot enough to melt it.Fumed silica is calcined in a rotary kiln. Hot air is blown through the kiln to desorb the hydrochloric acid from th

14、e surface of the silica.ChlorosilanesSilanes are chemical compounds consisting of a single atom of silicon combined with other elements or chemical groups. Chlorosilanes have one or more of the four available positions occupied by chlorine.The chlorosilanes used by Cabot for the manufacture of fumed

15、 silica are mainly silicon tetrachloride (SiCl4), some methyl trichlorosilane (Si(CH3)Cl3) and trichlorosilane (SiHCl3). The exact blend used by each manufacturing facility varies due to local availability.Co-solventsAn organic solvent that is water miscible.Examples of co-solvents are ethyl and iso

16、propyl alcohol, ethylene and propylene glycol, and most glycol ether solvents.Defoaming agentAn agent that makes bubbles burst and dissipate.Fumed silica can form an effective base for defoamers because of its small particle size.DensedMechanically compressed.Densed grades of fumed silica are formed

17、 by mechanically compressing the fumed silica. This increases the bulk density from 2.2 to 3 pounds per cubic foot (35 to 48 grams per liter) up to 4.5 to 5 pounds per cubic foot (72 to 80 grams per liter).DimerThe reaction product of two smaller units, monomers.In the TS-610 process, two molecules

18、of hydrolyzed DiMeDi, dimethyl dihydroxy saline, condense together to form a dimer. One hydroxyl group on one monomer reacts with a hydroxyl group on the other monomer to create a Si-O-Si bond, jointing them together. A water molecule, H-O-H is also formed in this reaction.DimethyldichlorosilaneChem

19、ical with the formula (CH3)2SiCl2.Dimethyldichlorosilane is the treating agent for TS-610.DipoleA pair of equal and opposite electric charges or magnetic poles of opposite sign separated by a short distance.See van der Waals Forces.DispersibilityThe relative ease with which the agglomerates of fumed

20、 silica are broken into smaller sizes.The dispersibility of fumed silica is vital to its performance in the manufacturing process. If not dispersed properly, fumed silica may not exhibit its highest efficiency.Dry carrierAn agent that turns liquids into dry powders.Fumed silica is an excellent adsor

21、bent and dry carrier for many substances, such as essential oils and stabilizers. These materials can easily be turned into free flowing dry powders, making them convenient to handle and mix into formulations.Durometer (Hardness)A measure of hardness based on the penetration of the indentor point of

22、 the durometer into the material under investigation.High values of durometer hardness indicate harder materials. Fumed silica improves measures of durometer hardness in elastomers and silicone rubbers.ElastomersA substance that can be stretched to at least twice its original length and can return v

23、ery rapidly to its original length when released.Elastomeric applications that use fumed silica include automotive spark plug boots and gaskets, weatherstripping, O-rings and bathtub caulk.ElongationThe percentage increase in length of a test specimen when it is stretched until it breaks.Fumed silic

24、a improves the elongation properties of elastomers or silicone rubbers.EmulsificationPromoting the formation of a stable emulsion.Fumed silica performs well as an emulsification agent for oil in water systems. It acts as a surfactant, coating the oil droplets and forming a stable emulsion.Epoxy resi

25、nA class of thermosetting polymers based upon the reactivity of the epoxide group.The most common type is a condensation product of epichlorohydrin and bisphenol-A. Epoxy resins exhibit excellent adhesion, strength, chemical resistance and electrical properties.FlocculationThe coming together of man

26、y small particles to form a large mass.The particles of fumed silica flocculate together via hydrogen bonding to form a network in a liquid. Within this network of fumed silica, the other particles in the material, such as the color pigments in a coating, are prevented from flocculating together and

27、 settling to the bottom of the container.Flow and levelingThe ability to form a smooth surface.Flow and leveling behavior is in dynamic balance with sag resistance. Increasing one behavior generally decreases the other.FluidizationThe ability of a powder to be easily picked up, suspended and moved a

28、bout by a stream of gas, such as air.Fumed silica can greatly improve the fluidization characteristics of fine powders, such as powder coatings. This greatly improves their application properties.Free-flowThe ability of a powder to move easily through orifices, pipes and other equipment without the

29、application of external forces (only gravity is needed).Fumed silica improves the flowability of powders, allowing them to flow easily out of bins and tanks, through valves and piping and it prevents the formation of clumps and lumps of material. A commonly used method of quantifying the flowability

30、 of a powder is the angle of repose test.GelcoatThe topcoat applied to composites to provide a smooth high appearance surface; these are almost always pigmented to provide the final color.Fumed silica is used primarily as an anti-sag agent in gelcoat formulations. It also provides anti-settling beha

31、vior for the color pigments used in the gelcoat.GlidantA term used in the pharmaceutical industry to describe materials that improve the flow characteristics of powder particles and granulations by reducing the friction between the particles.Grade M-5P is recommended for use in pharmaceutical tablet

32、 manufacturing to improve the flow of powdered drug formulations from the feed hopper to the die cavity of the tablet press.GradesTerm used by Cabot to distinguish between the many fumed silica products we manufacture.The untreated grades are divided by surface area whether they are densed or not. T

33、he densed untreated grades have a D as the last letter in the name. The treated grades are divided by the treatment applied and all their names begin with the letters TS.HexamethyldisilazaneChemical with the formula: (CH3)3-Si-NH-Si-(CH3)3.Hexamethyldisilazane is the treating agent for TS-500/TS-530

34、. It is a volatile liquid at room temperature.HoldoutThe ability of a coating or ink to stay on the surface of the substrate it has been applied over and not to sink into or be drawn down into any pores in the substrate.The anti-sag behavior imparted by fumed silica prevents the coating from flowing

35、 into the pores of the substrate or being drawn into pores by capillary action.HydrolysisA chemical reaction where a substance reacts with water and changes into a new compound(s).In the fumed silica process, the chlorosilanes are hydrolyzed to form silica and hydrochloric acid.HydrolyzeTo convert b

36、y hydrolysis see hydrolysis.HydrophilicCapable of being wetted by or taking up water.The surface chemistry of untreated fumed silica is hydrophilic. Untreated grades are easily wetted by water and will adsorb water from the humidity in the air.HydrophobicNot capable of being wetted by water or takin

37、g up water.The treated grades of fumed silica (the TS grades) cannot be wetted by water (they will float on water) without the use of surfactants or co-solvents and will not adsorb moisture from the humidity in the air during storage.HydrophobicityHaving hydrophobic characteristics see hydrophobic.H

38、ygroscopicReadily taking up and retaining moisture.Fumed silica improves free flow and prevents clumps in hygroscopic materials. The untreated grades of fumed silica are hygroscopic and will adsorb moisture from the humidity in the air.Index of RefractionThe amount a beam of light is bent in a parti

39、cular substance as compared with the light traveling in a vacuum.The index of refraction of fumed silica is 1.46. The index of refraction of air is 1.0. This index of refraction mismatch causes fumed silica to scatter light, giving it a white color in air. When fumed silica is incorporated into orga

40、nic resins and elastomers, most of which have an index of refraction close to 1.46, it will be colorless.Laminating applicationIn composites, this is the resin that is used to bind together the reinforcing fibers, such as fiberglass.Fumed silica provides anti-sag behavior to these resins to prevent

41、the resin from draining off the reinforcing fibers before the resin cures. It is used in both hand lay-up and sprayed chopped glass fabrication techniques.LSRLiquid Silicone Rubber.A class of silicone rubber compounds characterized by their low viscosity. They are able to cure via the addition of a

42、metal catalyst (typically platinum) to form solid highly elastomeric solid polymers.MattingThe reduction in the gloss (shininess) of the surface of a coating or ink.Fumed silica can provide a matting effect in coatings or inks if it is deliberately underdispersed. Fumed silica is not cost effective

43、against most other matting agents except in the satin range (30 to 40% specular gloss). Grade M-7D is recommended for this application.MistingFine droplets of inks flung off the rolls of high speed printing presses.Fumed silica can provide anti-misting. The thixotropic effect prevents the formation

44、of very fine droplets that can carry long distances. These stray droplets will create a cleaning problem and may blemish final printed products.ModulusThe expression of the ratio of tensile strength to elongation.Modulus is a measure of the stiffness of an elastomer, or how easily the elastomer can

45、be stretched. Adding fumed silica generally increases the modulus of the elastomer, making it stiffer and more difficult to deform.MorphologyThe structure or form of fumed silica at a particle or molecular level.The highly branched, chain-like aggregate structure of fumed silica gives it a unique mo

46、rphology.Polydimethylsiloxane (Silicone Fluid or Silicone Oil)Chemical with the formula (CH3)3-Si-O- (CH3)2-Si-On- Si-(CH3)2.Polydimethylsiloxane, also known as silicone oil, is the treating agent for TS-720.PolyolA substance that has more than one hydroxyl group per molecule.Low to medium molecular

47、 weight polyols are commonly used in making polyurethane elastomers, coatings and adhesives.PolyurethaneA class of polymers known for flexibility and chemical resistance.Polyurethanes come in one- and two-part formulas. In one-part polyurethanes, TS-720 should be used because these materials are sen

48、sitive to moisture. Both treated and untreated grades can be used in the polyol portion of two-part polyurethanes.PrecursorA substance, chemical, or chemical component from which another substance, chemical, or chemical component is formed.Chlorosilanes, such as silicon tetrachloride, are the precursor in the formation of fumed silica. Untreated fumed silicas are used