Of course silicone will repel liquid water, but we are talking here of
water in a gaseous phase and my experience is that it passes small
molecules, such as water, like a sieve. In the former case, it is a
question of the high surface tension of water, but single molecules, ata
a time, have no surface, therefore no surface tension.
Brian
Misner, Bruce wrote:
> Brian,
>
> This diaphram experiment does not take into account the surface
> wettability of Silicone which is supposed to be one of its major
> protective features (according to Dow) which precludes surface droplets
> from forming. Comments?
>
> Thanks,
> Bruce Misner
>
> -----Original Message-----
> From: Steve Gregory [mailto:[log in to unmask]]
> Sent: Monday, September 08, 2003 8:54 AM
> To: [log in to unmask]
> Subject: Re: [TN] Silicone conformal coating
>
> In a message dated 09/05/2003 2:03:30 AM Central Daylight Time,
> [log in to unmask] writes:
>
>
>> I thought I had reported the details of this in
>> my book, but could not find them today. Must have been somewhere else.
>
>
>
> Hi Brian!
>
> It is in your book, on page 329, at the bottom of the section where
> you talk about Silicone Elastomers.
>
> In your book you state that you made a diaphram of silicone that was
> 5mm thick, and 100mm in diameter. On one side the air was held at 40
> degrees C., and 95% RH, the other side at 5% RH. There was 1g of
> water vapor per day allowed to pass through the silicone diaphram.
> You stated that is 40 times worse than epoxies, and 20 times worse
> than polyurethanes.
>
> Do you have any idea about arcylics?
>
> Regards,
>
> -Steve Gregory-
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