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Tubular Kevlar degredation

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viciouspeanut

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Hey everyone,

I recently dug a rocket my of the garage that has a 1/2" tubular Kevlar shock cord on it. My question is with temperature (30-95 degrees) and humidity (often 80% or more) is this still good? Or do I need to replace it? I think it is on quick connects so not a big deal, just more of a curiosity.
 

Micromeister

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Hey everyone,

I recently dug a rocket my of the garage that has a 1/2" tubular Kevlar shock cord on it. My question is with temperature (30-95 degrees) and humidity (often 80% or more) is this still good? Or do I need to replace it? I think it is on quick connects so not a big deal, just more of a curiosity.
Low temps doesn't harm Kevlar. While Kevlar is Flame Retardent it is NOT Flame Proof. Each time it is subjected to ejection and afterburn temps over 426deg C or 900deg F it degrades a bit, eventually disintegrating to the point the Shock Cord will fail. Our ejection gases & after flame exceed this temperature.
 
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Handeman

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The storage in your garage should have no effect on the Kevlar at all.

Are you familiar with mule tape? It is usually a 1/4" to 1/2" flat braided tape pulled through conduit so wire can be pulled. What it used is twice as long as the conduit so when the wire is pulled through, there is still tape in the conduit. It is left in the until the next time it's needed. For dry, clean places they usually use nylon, but for wet, dirty places, Kevlar is used because it doesn't rot and break down like nylon does in challenging environments.

If you can sew the blocks with Kevlar thread or just tie knots, the 1/2" Kevlar mule tape makes very good and inexpensive shock cord.
 

CORZERO

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The storage in your garage should have no effect on the Kevlar at all.

Are you familiar with mule tape? It is usually a 1/4" to 1/2" flat braided tape pulled through conduit so wire can be pulled. What it used is twice as long as the conduit so when the wire is pulled through, there is still tape in the conduit. It is left in the until the next time it's needed. For dry, clean places they usually use nylon, but for wet, dirty places, Kevlar is used because it doesn't rot and break down like nylon does in challenging environments.

If you can sew the blocks with Kevlar thread or just tie knots, the 1/2" Kevlar mule tape makes very good and inexpensive shock cord.
Here is where I get mine:

http://aeroconsystems.com/cart/launch-recovery/kevlar-tape-for-recovery-bridles/
 

manixFan

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A flyer getting out of the hobby gave me a bunch of his old stuff. Most of it had been in his garage for 15 years or so, in the Texas heat. Lots of stuff fared poorly but the Kevlar was fine. It's very stable. I've reused it without issue and have no qualms about doing so.


Tony
 

Dave A

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Low temps don't harm Kevlar. While Kevlar is Flame Retardent it is NOT Flame Proof. Each time it is subjected to ejection and afterburn temps over 426deg C or 900deg F it degrades a bit, eventually disintegrating to the point the Shock Cord will fail. Our ejection gases & after flame exceed this temperature.
This is the reason I have cord protectors on all rockets (rigging) closest to the attachment point where hot gases will hit the cord.
 

viciouspeanut

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Awesome, thanks everyone. Glad it will be one less thing to work on!
 
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