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Q1 Permeation Products & Services Newsletter

Monday, April 8, 2024


 
 

Quarter 1 | March 2024

 
 

Pros and Cons of Masking While Testing

In an ideal scenario, we would test every film with the largest possible area since the larger the area, the better representation of the bulk material. However, there are often cases where one may have to mask the film to get any meaningful data. The effects of masking can be equally very beneficial and worrisome. Foil masks are most often used to increase the high-end of the instrument when testing poor barriers, or when there is limited material not large enough for a traditional test cell. When masking, one must be mindful that even if the instrument provides a test result, this value may not be accurate.

For example, results can be inaccurate in instances where the adhesive of the mask does not adhere properly to the material causing leakage at this interface. Also, some films may have thin spots or inconsistent coating which only become magnified when reducing the area (see figures below), so one should do their best to select an area that is a good representation of the material.

Masking also reduces the flux to the detector, which multiplies the high and low end of the instrument by the same factor. In cases where the structure is a good barrier, this may prove problematic if the unit loses sensitivity by a factor of 10. If the masked sample is near the “noise” of the instrument, an individual zero must be measured to subtract the background and ensure accuracy.

 

Convenient and Sustainable - Reduced Area Cartridges are a Reusable Permanent Mask

The industry standard permeation test cell size is 50 cm2. But if a customer has barrier film samples that are smaller in size, the film needs to be mounted in a mask to secure it in the standard test cell. Similarly, if the samples are a low barrier with a transmission rate that is above the normal range of the instrument using the standard 50 cm2 test cell, the sample needs to be mounted in a mask with a smaller area to be tested. To easily mount the sample, permeation masks have an adhesive backing that bond to the sample. This method of masking is one-time use only, so must be repeated for each test.

A preferred method is to take advantage of the exclusive interchangeable cartridge test cell system for MOCON's film permeation analyzers. The standard 50 cm2 test area cartridges come with every instrument. However, for applications where a smaller test area is required, MOCON offers reduced area cartridges with smaller test areas that mimic those of masks. The cartridges are available in a variety of sizes, allowing the customer to optimize the TR signal level for the samples to achieve the best test results. Since they are reusable, they also eliminate the disposal waste of using masks. The barrier sample is undamaged and can be used for other tests, thus reducing the waste.


To learn more about MOCON's reduced area cartridges, read the full product brochure below:

Read More


Humidity Effects Upon Transmission Rate

In our 2023 Q3 newsletter, we discussed how temperature impacts the transmission rate of gas through a material: Temperature Impact on Measured Gas Transmission Rate (ametekmocon.com). Likewise, humidity can influence a material’s measured transmission rate.

Some materials are fairly insensitive to moisture, while others can swell / change in the presence of humidity. Taken to extreme, some coated papers fall apart with very high humidity exposure. Understanding humidity impact upon the gas barrier properties of materials is key for characterizing a materials barrier performance for its intended storage and usage environment.

Below are OTR and WVTR graphs for two polymer materials. Material A is a “moisture sensitive” material that slightly swells with humidity exposure. Material B is fairly insensitive to humidity exposure.

For characterizing materials, one tool we find useful is MOCON’s Sequential Testing option:



Observations

Material A is very sensitive to humidity:

  • The 100%RH WVTR value is approximately 4X the WVTR of 50%RH. 
  • Additionally, the OTR has increased approximately 3X in value at 90%RH versus a moderate 50%RH OTR. 

Material B shows a linear relationship with WVTR:

  • The 100%RH value is 2X the 50%RH value.
  • What’s interesting is that for OTR, the transmission decreased as humidity rose. We see this with materials that are less affected by humidity.
  • One reason for this is that the high humidity does reduce the amount of oxygen in the test gas stream as the total test gas pressure is the sum of the oxygen and the water vapor molecules = atmospheric pressure. 

For characterizing materials, one tool we find useful is MOCON’s sequential testing option.

Summary

As with temperature, humidity conditions are important when defining the transmission rate test conditions. MOCON recommends using the conditions that are most appropriate for your project.

If the real-life test environment is unknown, the most common OTR test and CO2TR conditions are performed with dry gases, whereas the most common WVTR tests are conducted with 90%RH or 100%RH.
 


Resources

Revised or new application notes (click images below).

Curious for more? Uncover a wealth of knowledge on similar topics and industries in our Resource Library linked below:

Resource Library
Events

As "trade show season" in 2024 begins, we are excited to announce our attendance at multiple trade shows and conferences worldwide! Please see the schedule information below to check if we are located near you!

For customers located in the United States, we'll be at:

Cheese Expo 2024
  • Location: Milwaukee, WI
  • Days: Tuesday, April 16 - Thursday, April 18, 2024
  • Booth Number: 808
ASIC 2024
  • Location: Riverside, CA
  • Days: Tuesday, April 30 - Friday, May 3, 2024
  • Booth Number: 306
AIHA Connect 2024
  • Location: Columbus, OH
  • Days: Monday, May 20 - Wednesday, May 22, 2024
  • Booth Number: 1230
Global Pouch Forum
  • Location: Clearwater, FL
  • Days: Wednesday, May 29 - Friday, May 31, 2024
  • Booth Number: 302
Membrane Technology Forum
  • Location: St. Paul, MN
  • Days: Monday, June 10 - Wednesday, June 12, 2024
  • Booth Number: 31
Sensors Converge
  • Location: Santa Clara, CA
  • Days: Monday, June 24 - Wednesday, June 26, 2024
  • Booth Number: 1250
At this time, we are not attending any European shows or conferences in Q2 (April - June).

For customers located in Asia, we'll be at:

PACKCON 2024
  • Location: Shenzhen, China
  • Days: Wednesday, April 10 - Friday April 12, 2024
  • Booth Number: 7A300
CHINAPLAS 2024
  • Location: Shanghai, China
  • Days: Tuesday, April 23 - Friday, April 26, 2024
  • Booth Number: 5.2D35
Bakery China 2024
  • Location: Shanghai, China
  • Days: Tuesday, May 21 - Friday, May 24, 2024
  • Booth number: 21B76
APFE 2024
  • Location: Shanghai, China
  • Days: Monday, June 3 - Wednesday, June 5, 2024
  • Booth Number: 1T173
Hope to see you all in 2024!

Our list of 2024 trade shows and events is now final. Check the link below to our events page to see where we will be!

Events