Water Vapor Transmission Rate
Water Vapor Transmission Rate - Related Videos
02:34
Vapor Pressure
0 Views •
2020
When a liquid vaporizes in a closed container, gas molecules cannot escape. As these gas phase molecules move randomly about, they will occasionally collide with the surface of the condensed phase, and in some cases, these collisions will result in the molecules re-entering the condensed phase. The change from the gas phase to the liquid is called condensation. When the rate of condensation becomes equal to the rate of vaporization, neither the amount of the liquid nor the amount of the vapor...
01:18
Vaporization
0 Views •
2019
The physical form of a substance changes by changing its temperature. For example, raising the temperature of a liquid causes the liquid to vaporize (convert into vapor). The process is called vaporization—a surface phenomenon. For vaporization to occur, kinetic energy must be greater than the intermolecular forces that keep molecules bonded. The amount of energy needed to vaporize a quantity of liquid at a given pressure and a constant temperature is called the heat of vaporization. When...
03:28
Vapor Pressure Lowering
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2020
The equilibrium vapor pressure of a liquid is the pressure exerted by its gaseous phase when vaporization and condensation are occurring at equal rates: Dissolving a nonvolatile substance in volatile liquid results in a lowering of the liquid’s vapor pressure. This phenomenon can be explained by considering the effect of added solute molecules on the liquid's vaporization and condensation processes. To vaporize, solvent molecules must be present at the surface of the solution. The presence of...
06:33
A Rapid Protocol for Integrating Extrachromosomal Arrays With High Transmission Rate into the C. elegans Genome
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Cited by 59 •
2013
This protocol describes a rapid and low material consuming procedure for the integration of transgenic extrachromosomal arrays into the Caenorhabditis elegans genome using ultra violet (UV) irradiation. Furthermore, this protocol is particularly well suited for transgenic lines that transmit extrachromosomal arrays at a high rate.
11:32
Vapor-liquid Equilibrium
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2023
Source: Michael G. Benton and Kerry M. Dooley, Department of Chemical Engineering, Louisiana State University, Baton Rouge, LA Vapor-liquid equilibrium is paramount in engineering applications such as distillation, environmental modeling, and general process design. Understanding the interactions of components in a mixture is very important in designing, operating and analyzing such separators. The activity coefficient is an excellent tool for relating molecular interactions to mixture...
FAQs
The vapor-pressure gradient provides the driving force for molecular diffusion through a material. Water vapor moves from the side with higher vapor pressure toward the side with lower vapor pressure, so changing the humidity conditions can alter the measured transmission rate. Engineers must therefore control and report the temperature and humidity gradient when comparing barrier performance.
Material thickness and internal structure influence the path that water-vapor molecules must travel. A thicker or less permeable barrier generally restricts molecular movement, while structural features that permit easier transport can increase passage through the material. Evaluating these factors helps engineers compare films, coatings, membranes, and enclosure materials under defined testing conditions.
Temperature and humidity establish the vapor-pressure conditions that drive transmission, making them essential parts of a meaningful measurement. If either condition changes, the amount of vapor moving through the material may also change. Specifying these variables allows engineers to interpret results consistently and relate barrier performance to a particular operating environment.
A basic evaluation establishes a controlled temperature and humidity gradient across the material, allows vapor to pass through by molecular diffusion, and determines the transmitted amount over a specified time and area. The resulting value is interpreted alongside the material’s thickness, structure, and permeability to assess its barrier behavior.
Engineers apply this measurement to barrier films, packaging, coatings, membranes, and electronic enclosures. These materials differ in structure and intended function, but each may need to limit moisture movement to maintain performance. Comparing their transmission behavior helps guide material selection and evaluate whether a design provides the required protection against water vapor.
The measurement helps engineers determine whether a material can protect moisture-sensitive products, preserve food and pharmaceuticals, or shield electronic systems. It also supports evaluation of building materials and the durability of engineered systems. In each case, the result connects moisture transport with practical concerns such as product protection, material performance, and service life.