Best nylon for fabrics under hot/wet environments
Best nylon for fabrics under hot/wet environments
(OP)
Doing some research, again, to find a fabric that can withstand 220-230 deg. F, wet (pressurized hot water) environment. The pH condition of the water can be assumed neutral (rare) to fairly strongly alkaline (to pH of 10, but could be limited to less than that if it improves the longevity of the fabric).
This is to form a reinforcement fabric for an EPDM rubber seal. The current winner in these conditions is meta-polyaramid (Nomex), but this material has become difficult to source.
PET fabric has been tried in the past, and come up a failure due to fairly rapid hydrolysis degradation of the fabric. The recent discussion here of PEN and its use for fibers has me thinking about running some trials with that material.
Nylon, or rather polyamides, come up as possibly good for these conditions. Is there a preferred resin that gives the best combination of hydrolysis resistance and can be fiber-spun?
This is to form a reinforcement fabric for an EPDM rubber seal. The current winner in these conditions is meta-polyaramid (Nomex), but this material has become difficult to source.
PET fabric has been tried in the past, and come up a failure due to fairly rapid hydrolysis degradation of the fabric. The recent discussion here of PEN and its use for fibers has me thinking about running some trials with that material.
Nylon, or rather polyamides, come up as possibly good for these conditions. Is there a preferred resin that gives the best combination of hydrolysis resistance and can be fiber-spun?





RE: Best nylon for fabrics under hot/wet environments
Nylon 6.6 can be stabilised reasonably well to hydrolysis, but will still be plasticised by the water at those temps, as will the 11 and 12, but to only about half the extent.
Data for both hydrolysis and properties after water absorption at those temperatures will be hard to come by. Data at 100 dec C will be available. I may even have it in my library.
Regards
Pat
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RE: Best nylon for fabrics under hot/wet environments
RE: Best nylon for fabrics under hot/wet environments
The number in nylon names equals the number of carbons between functional groups and it's the functional groups that are attractive to water and also degraded by it. Higher number means less influence from water.
Also, as a general rule, the more the functional groups and the more evenly spaced, the more crystalline and therefore the more short term temperature resistance and strength.
Regards
Pat
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RE: Best nylon for fabrics under hot/wet environments
What about oriented polypropylene fibers or fabric? That would have great chemical resistance, pH insensitive and more compatible with EPDM so you can get better adhesion.
Chris DeArmitt - PhD FRSC CChem
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RE: Best nylon for fabrics under hot/wet environments
http://www.propexbrands.com/
Chris DeArmitt - PhD FRSC CChem
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RE: Best nylon for fabrics under hot/wet environments
Are poly-aramids not considered polyesters? Maybe they are a unique class. I know Nomex holds up well for us, we are trying to see if there are similar textile polymers we could substitute.
Dunno why they limited my stars. Will try it again...
RE: Best nylon for fabrics under hot/wet environments
RE: Best nylon for fabrics under hot/wet environments
For PP fabric check here
http://www.curvonline.com/
The datasheet says the PP material softens at 175C.
Chris DeArmitt - PhD FRSC CChem
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RE: Best nylon for fabrics under hot/wet environments
From memory, I thought Aramid was sensitive to hydrolysis but maybe I am thinking para aramid or Kevlar type. The memories are getting dimmer.
I always thought of aramid as a thermoset polyamide in effect.
BT
Have you tried Technora from Teijin or Akzo Nobel or whoever now handles it in the US, that is if the trade embargo implemented by DuPont has lifted. DuPont can hardly continue to claim commercial damage from imports if they cannot supply the market.
My data is nearly 20 years old, so there may be other players. I have vague memories of a second Japanese source and an Italian source, but both where pilot plant status and they may have been para only, not meta.
Regards
Pat
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RE: Best nylon for fabrics under hot/wet environments
There's a new high modulus PP fiber on the market called Innegra S.
http://www.innegrity.com/index.php
It has a kind of micro porous surface structure that I havent seen before in any fiber. They claim it provides a better grip for rigid composites and perhaps works with EPDM as well.
regards,
Claus
RE: Best nylon for fabrics under hot/wet environments
Yes, I've been watching the Teijin stuff rattle out, not sure but I think they are the current supplier for our supplier. I know DuPont now uses the Technora patent to produce aramids, as it is a cheaper/more efficient method (according to wiki and other online sources).
All,
Looking at PP a bit more closely, but everything I see shows the higher-load heat deflection temperature down below our use temperature. Would probably make a lovely reinforcement at more moderate temperatures, though, and as Chris noted, should play nicely with EPDM.
Thanks, we have some new avenues to explore.