What is the WVTR of polyethylene?
As shown in Table 9, gauge for gauge, OPP provides the best WVTR of all common polymer packaging films….Relevance to package performance.
| Film Type | WVTR @ 100°F (38°C), 90% RH for 1 mil film | |
|---|---|---|
| (g/100 in2/24 hr) | (g/m2/24 hr) | |
| LDPE (low density polyethylene) | 1.0 – 1.5 | 16 – 23 |
How is WVTR calculated?
The water vapour transmission rate (WVTR) is the rate of water vapour permeating through the film. In this work, the WVTR is determined from the slope of the regression line of sample weight versus time graph whereby the slope is then divided by the area of the film being exposed to the transmission (Equation 10).
What is WVTR packaging?
Definition: Water Vapor Transmission Rate (WVTR) or Moisture Vapor Transmission Rate (MVTR) is the rate at which water vapor will permeate through solid material over a specific period of time. Rate in Packaging: When referring to packaging, WVTR is the rate at which water vapors will permeate the package wall.
Is plastic permeable to air?
plastics are permeable to oxygen and water vapor to a certain degree [24]. Table 3 shows the water vapor and oxygen permeability for selected films used for food-packaging applications [22,26]. …
What is WVTR and OTR?
Oxygen Transmission Rate (OTR) is the measurement of the amount of oxygen gas that passes through a substance over a given time period. Moisture (Water) Vapor Transmission Rate (MVTR/WVTR) is the measurement of amount of water vapor that permeates through the substance over a given time period.
What is ASTM E96?
Water Vapor Transmission ASTM E96. Scope: The test evaluates the water vapor transfer through semi-permeable and permeable samples. The data can be used by manufacturers and designers and is often important in packaging applications.
What is water Vapour Permeance?
vapor permeance – the. time rate of water vapor transmission through unit area of flat material or construction. induced by unit vapor pressure difference between two specific surfaces, under. specified temperature and humidity conditions.
Why is WVTR important in packaging?
Increasing WVTR values indicate greater permeability, and lower ability to keep dry products dry, and moist products moist. When choosing a packaging film, MVTR is often balanced with oxygen transmission rate (OTR) to provide the most appropriate barrier characteristics for a particular product’s needs.
Is HDPE permeable to water?
5 High Density Polyethylene (HDPE) Oxygen barrier in extruded PC/HDPE (90/10, 40 μm) film was 2.9 ± 0.2 barrer, while recrystallization at 128°C showed oxygen permeability of 1.2 ± 0.1 barrer. The water permeability also decreased from 5.3 ± 0.2 g mil/100 in.
Are all plastics permeable?
In contrast to glass or metal packaging materials, packages made with plastic are permeable at different degrees to small molecules like gases, water vapour, and organic vapour and to other low molecular weight compounds like aromas, flavour, and additives present into food.
What does Mvtr stand for?
A moisture vapor transmission rate (MVTR), also referred to as a water vapor transmission rate, is the rate that water vapor will transfer through a given substance.
What does OTR mean in packaging?
oxygen transmission rate
The oxygen transmission rate (OTR) is determined using ASTM Standard D 3985-81 and the water vapor transmission rate (WVTR) is measured as per ASTM Standard F 372-78. Permeation of gases and water vapor through polymers is of particular interest in the packaging industry.
How does the thickness of an OPP affect WVTR?
The most obvious factor that impacts WVTR is thickness: if one OPP is twice as thick as another OPP with the same product design, the thicker film’s WVTR will be half the value of the thinner one; this is because WVTR is an inherent, bulk film property of OPP.
How are additives and copolymers related to WVTR?
Additives and copolymer resin layers can account for differences of up to 30%. Process: Normal differences in process conditions between one orienter and another account for about 5% variation in WVTR values. (WVTR is reduced through orientation, because the crystalline regions of the polymer matrix are aligned.
Why is WVTR used to measure moisture protection?
WVTR is the standard measurement by which films are compared for their ability to resist moisture transmission, with lower values indicating better moisture protection. Only values reported at the same temperature and humidity can be compared, because transmission rates are directly affected by both of these parameters.
How does WVTR affect the performance of an OLED?
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 with increasing temperature.
https://www.youtube.com/watch?v=v6AstbY1Gx0