Posted by Diffusion in Polymers Platform on November 14, 2004 at 11:52:57:

In Reply to: inroganic fillers and water permeation posted by Olivier Pinto on November 08, 2004 at 19:21:16:

Dear Olivier Pinto,

When you are dealing with a 50/50 w/w LDPE (low density polyethylene) -Aluminium Hydroxide (ATH) / Silica Particles compound, the following can be stated:

The interface of these particles with the polymer matrix is often insufficient to let the material act as a composite from the diffusion viewpoint. This means that small molecules, like helium, hydrogen, methane, water, etc, accumulate at the interface of the filler particles. This enhances the solubility of the respective molecule in the composite material, and seemingly decreases the diffusivity coefficient due to the fact that a some part gets immobilized at the particle interface and another part diffuses through the polymer matrix. Thus the particles act for example as moisture scavengers. From our viewpoint such a moisture scavenger is not positive: the overall weight increases and the composite properties will behave unstable when system temperature and pressure change rapidly. Moreover mind that a chemical reaction with the polymer chains results in the same phenomenon.

Best Regards,
Diffusion in Polymers

: Hello,

: could you please give a general statement with regard to the impact of inorganic fillers dispersed within polymeric matrixes on the resulting water permeation properties of the composite ?

: I have in mind that increasing filler content will decrease permeation, but I would appreciate a more detailed theoretical understanding of the phenomena involved.

: Thanks in advance.
: best regards,