Instruments or test equipment are designed for adsorption and desorption studies. Adsorption is the physicochemical adhesion of a substance (liquid, gas, or dissolved solids sorbate) onto the surface of a solid or liquid. Adsorption results in the accumulation of molecules of gases, or ions or molecules of liquids, at the surfaces of contacting solids or liquids.
Desorption is the release of the molecular layer of the adsorbed on the surface of an absorbent. Desorption can be caused by high temperature, high humidity, or scalping.
Chemisorption is the process by which sorbates are adsorbed and chemically changed by a reaction with the sorbent material.
Physisorption is the process where molecules are physically bonded to the surface by Van der Vals and weak dipole forces. Physisorption processes are more reversible, and weaker bonds are formed compared to chemisorption processes. Sorption, adsorption, and desorption can be determined by measuring weight changes of the sorbate material.
Testers evaluate the amount of water absorbed by a material. Note that absorption differs from adsorption. Absorption takes in water past the surface and into the material itself. Adsorption is the accumulation of vapor or water onto the surface of a material. Plastics and paper materials can have varying degrees of water absorption. Typically, COBB testers are used in the paper industry to determine water absorption characteristics.
Brittleness or friability is a measure of how easily a material can be fractured, crushed, or broken. Brittleness can be determined by impacting the material with a controlled load. A very friable plastic, mineral, or abrasive would be considered weak and easily crushed or broken. A low-friability abrasive or mineral would be considered tougher and more difficult to mill or crush. The brittle point or ductile-to-brittle transition temperature is determined by testing a material at a series of decreasing temperatures until brittle behavior is observed.
Testers or test equipment determine the cohesion or internal friction of materials. These properties can be important in understanding the processing or end-use function of powders, soils, sands, rocks, and granular materials. In geophysical applications, bore hole or shear tests are used to determine cohesion and internal friction.
Testers or test equipment determine the compactability or compressibility of materials. These properties can be important in understanding the processing or end-use function of powders, foams, filter media and other compressible or porous materials.
Consistency is the amount of dry solids (% solids) or fibers in pulp or paper stock. It determines how the pulp can be formed and processed into paper. If the consistency is too thin or too thick, a paper web will not form properly. The specific consistency required depends on the paper-forming equipment used and the product being formed.
Contamination analysis determines the amount of dirt, inclusion, slag, shives, swarf, grinding debris, bacterial, microbial or other undesirable foreign contaminants in a material. The amount of shives, dirt and stickle in pulp or paper can influence processability. Contaminants in a coating, ink, or adhesive mixture can result in streaks or repeating defects in the finished product.
An evaluation of the cleanliness, hygiene, or level of sterilization is very important for food, beverages, cosmetics, drugs, medical, biotech and pharmaceutical products. Specialized instruments or test equipment may be used to evaluate the cleanliness, hygiene, or level of sterilization applied to a material. Testers often use the detection of bacteria or ATP to determine cleanliness or sanitary properties. UV light sources can also be useful.
Test equipment is designed for core sampling or analysis. Coring or core sampling is done on powder bodies, soils, and geological materials to capture a true picture of variation through the material. Testing a powder or granular material by "scooping" from the surface can be misleading due to settlement and segregation effects.
Loose packed density (LPD) or aerated density is the density of the powder or particulate body without any settlement, mechanical agitation, vibration, or tapping. Usually, loose packed density measurements are made by determining the mass of powder in a sample container of known volume.
Tap or packed density is the density of the powder or particulate body after settlement from tapping, mechanical agitation, vibration, or light packing (not compaction or consolidation). Often, both loose packed and tap density measurements are made to determine the Hausner ratio, which is calculated by dividing the loose-packed density by the tap density. Carr index is also related to loose packed and tap densities. The Carr index and Hausner ratio provide an indication of flowability.
Disintegration or dissolution is the rate at which a chemical, material, drug, or pharmaceutical dissolves when put into water, another solvent or a simulated oral, digestive, or circulatory environment.
Flash point is the lowest temperature at which a liquid can form an ignitable mixture in air near the surface of the liquid. The lower the flash point, the easier it is to ignite the material.
Flammability is a measure of how quickly a material will ignite and propagate combustion. Underwriters Laboratories (UL) and the National Fire Protection Association (NFPA) have standards for the fire testing of materials. The UL 94 standard for flammability testing describes 12 flame classifications based on small-scale flame tests. UL 94 determines a material’s tendency to either propagate or extinguish a flame on an ignited and burning sample. UL 746A determine a material’s resistance to ignition.
Flowability provides an indication of the flow characteristics of a powder, granular material, slurry, or liquid. Powder flowability is determine through Carr index, basic flow index (BFI), Hausner ratio, angle of repose, internal friction, degree of floodability and other specialized or proprietary flow tests. Floodability is the degree to which a powder self-aerates and flows like a liquid. Slump tests determine the flowability or workability of a concrete, mortar or cement based material.
Friction testers test friction force, the resisting force tangential to the interface between two bodies when, under the action of an external force, one body moves or tends to move relative to the other. Coefficient of friction (COF,) values are often determined. Friction force = () x (Normal Force). The COF can be dynamic (sliding) or static. Wall friction between a powder and die wall is important in understanding compaction for manufacturing pills, metal parts, ceramics, and other compacts.
Densometers are used for measuring porosity, air-permeability, or air resistance of sheet-like or bulk materials such as paper, woven cloth, porous plastics, nonwoven textiles, filtration media, and membranes. Densometers measure by determining the time required to drive or flow a fixed, known volume of air through a sample. Some densometers or densometry instruments also provide smoothness and softness indications through permeation measurements. Nuclear densometers are used to measure porosity, density, and moisture content in soil, asphalt, concrete and pavement field applications.
Porosimeters measure the pore volume and distribution in a bulk material. They use either liquid intrusion into pores or liquid extrusion from pores to measure pore volume. Porometers or bubble point testers determine the point at which pressure can overcome capillary action in a porous material.
The specific surface area of a powder is determined by physical adsorption of a gas on the surface of the solid, and by measuring the amount of adsorbate gas corresponding to a monomolecular layer on the surface.
Surface area can be determined by measuring the amount of material required to form a single layer - a monolayer - on the surface. If the area per molecule or ion adsorbed is known, then the total surface area from such a measurement can be calculated.
Surface tension instruments measure a fluid’s surface tension or energy, a tangential force that keeps a fluid together at the air/fluid interface. Lower surface energy materials are more easily wet by higher surface energy liquids. Wettability is determined by the relative surface and surface tension or energies of the materials in contact.
Contact or wetting angles are a measure of wettability. Contact angles are determined by the relative surface and surface tension or energies of the materials in contact. The equation that governs wetting angle () is SA (solid-air) - SA (Liquid-solid) = SA (liquid-air)cos() . SA (liquid-solid) is the surface energy of the liquid-solid interface or interfacial energy. SA (liquid-air) is the surface energy of the liquid-air interface or interfacial energy. SA (solid-air) is the surface energy of the solid-air interface or interfacial energy.
Other unlisted, specialized, or proprietary configurations.
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Devices test substances that coat, fasten, bond, or seal materials. Adhesives that bond and seal are called adhesive sealants. Coatings are thin layers of protective or decorative compounds that are bonded to the surface of a substrate by a variety of methods. Wetting and surface energy are key properties in the processing and function of coatings, adhesives, and sealants.
Ceramics consist of oxides, carbides, nitrides, carbon, and other non-metals with high melting points. Ceramics are suitable for applications requiring wear resistance, refractoriness, low electrical resistivity, or other specialized characteristics.
Devices are designed to evaluate the properties or workability of concrete, mortar, or cement products. Concrete is a mixture of Portland cement, water, and aggregate. Mortar contains these same ingredients along with hydrated lime and sand to facilitate workability and decrease working time.
Devices are designed to test metals or alloys with two or more metallic elements. As a category, metals include electropositive elements that are generally good conductors of heat and electricity, and that can be melted or fused, hammered into thin sheets, or drawn into wires.
Devices are designed to test polymers, plastics, and elastomers. Polymers are organic, synthetic, or processed materials typically consist of thermoplastic or thermosetting resins. Plastic testers or test equipment tests any of various organic compounds produced by polymerization. These materials can be molded, cast, or extruded into various shapes and films. Rubbers and elastomers are polymers that exhibit very high elasticity and resilience compared to plastic polymeric materials.
Other unlisted, specialized, or proprietary media.
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) values are often determined. Friction force = (
) is SA (solid-air) - SA (Liquid-solid) = SA (liquid-air)cos(