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Water Vapor Transmission Rate
Moisture vapor transmission rate (MVTR), also water vapor transmission rate (WVTR), is a measure of the passage of water vapor through a substance. It is a measure of the permeability for vapor barriers. There are many industries where moisture control is critical. Moisture sensitive foods and pharmaceuticals are put in packaging with controlled MVTR to achieve the required quality, safety, and shelf life. In clothing, MVTR as a measure of breathability has contributed to greater comfort for wearers of clothing for outdoor activity. The building materials industry also manages the moisture barrier properties in architectural components to ensure the correct moisture levels in the internal spaces of buildings. Optoelectronic devices based on organic material, generally named OLEDs, need an encapsulation with low values of WVTR to guarantee the same performances over the lifetime of the device. MVTR generally decreases with increasing thickness of the film/barrier, and increases ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Permeation
In physics and engineering, permeation (also called imbuing) is the penetration of a wikt:permeate#English, permeate (a fluid such as a liquid, gas, or vapor) through a solid. It is directly related to the concentration gradient of the permeate, a material's intrinsic permeability, and the materials' mass diffusivity. Permeation is modeled by equations such as Fick's laws of diffusion, and can be measured using tools such as a minipermeameter. Description The process of permeation involves the diffusion of molecules, called the permeant, through a membrane or interface. Permeation works through diffusion; the permeant will move from high concentration to low concentration across the interface. A material can be semipermeable, with the presence of a semipermeable membrane. Only molecules or ions with certain properties will be able to diffuse across such a membrane. This is a very important mechanism in biology where fluids inside a blood vessel need to be regulated and controlle ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Perm (unit)
A perm is a unit of permeance or "water vapor transmission" given a certain differential in partial pressures on either side of a material or membrane. Definitions ;U.S. perm :The U.S. perm is defined as 1 grain of water vapor per hour, per square foot, per inch of mercury. : ;Metric perm :The metric perm (not an SI unit) is defined as 1 gram of water vapor per day, per square meter, per millimeter of mercury. : ;Equivalent SI unit :The equivalent SI measure is the nanogram per second per square meter per pascal. : The base normal SI unit for permeance is the kilogram per second The second (symbol: s) is a unit of time derived from the division of the day first into 24 hours, then to 60 minutes, and finally to 60 seconds each (24 × 60 × 60 = 86400). The current and formal definition in the International System of U ... per square meter per pascal. : German Institute for Standardization unit A variant of the metric perm is used in DIN Standard 53122, where p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Drug Manufacturing
Pharmaceutical manufacturing is the process of industrial-scale synthesis of pharmaceutical drugs as part of the pharmaceutical industry. The process of drug manufacturing can be broken down into a series of unit operations, such as milling Milling may refer to: * Milling (minting), forming narrow ridges around the edge of a coin * Milling (grinding), breaking solid materials into smaller pieces by grinding, crushing, or cutting in a mill * Milling (machining), a process of using ro ..., Granulation (process), granulation, Coated tablet, coating, tablet pressing, and others. Scale-up considerations Cooling While a laboratory may use dry ice as a cooling agent for reaction selectivity, this process gets complicated on an industrial scale. The cost to cool a typical reactor to this temperature is large, and the viscosity of the reagents typically also increases as the temperature lowers, leading to difficult mixing. This results in added costs to stir harder and replace part ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Food Technology
Food technology is a branch of food science that addresses the production, preservation, quality control and research and development of food products. It may also be understood as the science of ensuring that a society is food secure and has access to safe food that meets quality standards. Early scientific research into food technology concentrated on food preservation. Nicolas Appert's development in 1810 of the canning process was a decisive event. The process wasn't called canning then and Appert did not really know the principle on which his process worked, but canning has had a major impact on food preservation techniques. Louis Pasteur's research on the spoilage of wine and his description of how to avoid spoilage in 1864, was an early attempt to apply scientific knowledge to food handling. Besides research into wine spoilage, Pasteur researched the production of alcohol, vinegar, wines and beer, and the souring of milk. He developed pasteurization – the proces ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Psychrometrics
Psychrometrics (or psychrometry, ; also called hygrometry) is the field of engineering concerned with the physical and thermodynamic properties of gas-vapor mixtures. History With the inventions of the hygrometer and thermometer, the theories of combining the two began to emerge during the sixteenth and seventeenth centuries. In 1818, a German inventor, Ernst Ferdinand August (1795-1870), patented the term “psychrometer”, from the Greek language meaning “cold measure”. The psychrometer is a hygrometer, hygrometric instrument based on the principle that dry air enhances evaporation, unlike wet air, which slows it. Common applications Although the principles of psychrometry apply to any physical system consisting of gas-vapor mixtures, the most common system of interest is the mixture of water vapor and air, because of its application in HVAC, heating, ventilation, and air-conditioning and meteorology. In human terms, our thermal comfort is in large part a consequence ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vapor Barrier
A vapor barrier (or vapour barrier) is any material used for damp proofing, typically a plastic or foil sheet, that resists diffusion of moisture through the wall, floor, ceiling, or roof assemblies of buildings and of packaging to prevent interstitial condensation. Technically, many of these materials are only vapor retarders as they have varying degrees of Permeation, permeability. Materials have a moisture vapor transmission rate (MVTR) that is established by standard test methods. One common set of units is g/m2·day or g/100in2·day. Permeability can be reported in perm (unit), perms, a measure of the rate of transfer of water vapor through a material (1.0 US perm = 1.0 grain/square-foot·hour·inch of mercury ≈ 57 SI perm = 57 ng/s·m2·Pa). American building codes started classifying vapor retarders in the 2007 IRC supplement. They are Class I 570 SI perm) – such as unpainted gypsum board and plaster, unfaced fiber glass insul ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Shelf Life
Shelf life is the length of time that a commodity may be stored without becoming unfit for use, consumption, or sale. In other words, it might refer to whether a commodity should no longer be on a pantry shelf (unfit for use), or no longer on a supermarket shelf (unfit for sale, but not yet unfit for use). It applies to cosmetics, foods and beverages, medical devices, medicines, explosives, pharmaceutical drugs, chemicals, tyres, batteries, and many other perishable items. In some regions, an advisory ''best before'', mandatory ''use by'' or ''freshness date'' is required on packaged perishable foods. The concept of expiration date is related but legally distinct in some jurisdictions. Background Shelf life is the recommended maximum time for which products or fresh (harvested) produce can be stored, during which the defined quality of a specified proportion of the goods remains acceptable under expected (or specified) conditions of distribution, storage and display. Accordi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Permeation
In physics and engineering, permeation (also called imbuing) is the penetration of a wikt:permeate#English, permeate (a fluid such as a liquid, gas, or vapor) through a solid. It is directly related to the concentration gradient of the permeate, a material's intrinsic permeability, and the materials' mass diffusivity. Permeation is modeled by equations such as Fick's laws of diffusion, and can be measured using tools such as a minipermeameter. Description The process of permeation involves the diffusion of molecules, called the permeant, through a membrane or interface. Permeation works through diffusion; the permeant will move from high concentration to low concentration across the interface. A material can be semipermeable, with the presence of a semipermeable membrane. Only molecules or ions with certain properties will be able to diffuse across such a membrane. This is a very important mechanism in biology where fluids inside a blood vessel need to be regulated and controlle ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Packaging
Packaging is the science, art and technology of enclosing or protecting products for distribution, storage, sale, and use. Packaging also refers to the process of designing, evaluating, and producing packages. Packaging can be described as a coordinated system of preparing goods for transport, warehousing, logistics, sale, and end use. Packaging contains, protects, preserves, transports, informs, and sells. In many countries it is fully integrated into government, business, institutional, industrial, and for personal use. ''Package labeling'' (American English) or ''labelling'' (British English) is any written, electronic, or graphic communication on the package or on a separate but associated label. Many countries or regions have regulations governing the content of package labels. Merchandising, branding, and persuasive graphics are not covered in this article. History of packaging Ancient era The first packages used the natural materials available at the time: baskets of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oxygen Transmission Rate
Oxygen transmission rate (OTR) is the measurement of the amount of oxygen gas that passes through a substance over a given period. It is mostly carried out on non-porous materials, where the mode of transport is diffusion, but there are a growing number of applications where the transmission rate also depends on flow through apertures of some description. It relates to the permeation of oxygen through packaging to sensitive foods and pharmaceuticals. Measurement Standard test methods are available for measuring the oxygen transmission rate of packaging materials. Completed packages, however, involve heat seals, creases, joints, and closures which often reduce the effective barrier of the package. For example, the glass of a glass bottle may have an effective total barrier but the screw cap closure and the closure liner might not. ASTM standard test methods include: * F3136 Standard Test Method for Oxygen Gas Transmission Rate through Plastic Film and Sheeting using a Dynamic A ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Moisture Sorption Isotherm
The relationship between water content and equilibrium relative humidity of a material can be displayed graphically by a curve, the so-called moisture sorption isotherm. For each humidity value, a sorption isotherm indicates the corresponding water content value at a given temperature. If the composition or quality of the material changes, then its sorption behaviour also changes. Because of the complexity of sorption process the isotherms cannot be determined explicitly by calculation, but must be recorded experimentally for each product. The relationship between water content and water activity (aw) is complex. An increase in aw is usually accompanied by an increase in water content, but in a non-linear fashion. This relationship between water activity and moisture content at a given temperature is called the moisture sorption isotherm. These curves are determined experimentally and constitute the fingerprint of a food system. BET theory (Brunauer-Emmett-Teller) provides a calcu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Carbon Dioxide Transmission Rate
Carbon dioxide transmission rate (COTR) is the measurement of the amount of carbon dioxide gas that passes through a substance over a given period. It is mostly carried out on non-porous materials, where the mode of transport is diffusion, but there are a growing number of applications where the transmission rate also depends on flow through apertures of some description. See also * Moisture vapor transmission rate * Permeation * Oxygen transmission rate *Packaging Packaging is the science, art and technology of enclosing or protecting products for distribution, storage, sale, and use. Packaging also refers to the process of designing, evaluating, and producing packages. Packaging can be described as a coo ... Further reading * Yam, K. L., "Encyclopedia of Packaging Technology", John Wiley & Sons, 2009, * Massey, L. K., "Permeability Properties of Plastics and Elastomers", 2003, Andrew Publishing, Standards * ASTM D1434 - Standard Test Method for Determining Gas Permeability ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
