Permeability of oxygen in polypropylene  


Posting by pantelis pantani on April 17, 2008 at 15:36:08.

As you might know most of the fabricants of hydronic underfloor heating systems use crosslinked polyethylene (PEX) pipe with an Oxygen diffusion barrier made by an EVAL layer, outside the pipe. In separate cases, very few fabricants use Random Copolymer Polypropylene (PP) (Like the German Multibeton).

This pipe is not provided with a separate Oxygen barrier, while the fabricants do not provide information about the degree of oxygen diffusivity through the walls of these pipes (or I was not able to find it ). Do you have anything about this case?

Regards,
Pantelis Pantani


          follow up posts
    On 04/20/2008 suleyman deveci posts: dear pantelis,

    you could use Dab, diffusion coeff. of O2 through PP to calculate total transport of O2 throug the pipe walls via fick's 1. law. the main problem is to find out Dab.

    i have found Dab for O2 through PPRC experimentally and it is about1.9 * 10^-12 m2/s.

    you can also measure the oxygen transport in accordance
    with DIN 4726 / DIN 4729
    [responses: 3]

      On June 29, 2008 at 14:34:52 Suneetha Burla posts:
      I am interested in the diffusion coefficient and permeation rate of butane and propene in polypropylene. With this regard I need some detailed information regarding the following topics:

      1. Diffusion of liquids and gases through thermoplastic polymers. The
      temperature at which diffusion occurs would be below the polymer glass
      transition temperature. In other words, the polymer is glassy. The
      polymer may be amorphous or semicrystalline. Candidate polymers of
      interest are polypropylene and polyacrylonitrile. Candidate diffusing
      molecules are butane gas and hexane as a liquid. Also, water and
      alcohol. Diffusion could be Fickian (case I) or non-Fickian (case II).

      2. What are the most common experimental techniques used? How does one
      analyze the data? How does one compute solubility, diffusivity and
      permeability?

      3. What theories can be used to correlate and predict diffusion through
      polymers? Can we do any accelerated experiments?

      4. What happens to the polymer (i.e. what physical and chemical
      structural chages occur and why) when glassy polymers or rubber gaskets
      come in contact with hydrocarbon gases and liquids? What happens when
      they come in contact with water or alcohol containing either fragrences
      or insecticides?

      5. Diffusion of a liquid through a polymer film when the liquid
      contains two dissolved solutes.

      Thanks for your effort!

      Suneetha
      [responses: 0]


      On 04/23/2008 composite agency posts: Dear Suleyman Deveci,

      Many thanks for sharing your knowledge on diffusion and permeation with us! If you want to subscribe to our interesting forum topics notification, please let me know (in that case, you can easily join any discussion you would like to, straight from your mailbox!).

      I am sure your feedback and remarks will be highly appreciated by other colleagues in this area!

      Thanks

      Kind Regards,
      Sijmon
      Composite Agency
      [responses: 1]



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