We know the properties & pros/cons of nylon vs. dyneema. What about polyester and polyethylene?

So, regarding certain climbing softgoods - mostly slings and dogbones - most of us know about the respective properties of nylon (not as static, absorbs more water, handles repeated flexing very well, etc.) vs. dyneema (more static, absorbs less water, more slippery, stronger per unit of mass - so less material is needed to achieve the same strength ratings, etc.)

How about polyester?  Petzl has a few slings and dogbones that, upon first glance seem to be made of nylon, but are actually made of polyester

- https://www.petzl.com/CA/en/Sport/Anchors/ANNEAU

- https://www.petzl.com/CA/en/Sport/Carabiners-and-quickdraws/EXPRESS

- https://www.petzl.com/CA/en/Sport/Carabiners-and-quickdraws/AXESS

How about polyethylene?  Petzl has a sling made from "high-modulus polyethylene"

- https://www.petzl.com/CA/en/Professional/Anchors/PUR-ANNEAU

Anyone know how these materials compare to nylon and dyneema?

Polyester is typically stiffer and more durable than nylon. 

Dyneema is high modulus polyethylene 

I'm glad you asked because I was wondering. My Camp photon quickdraws dogbones are polyester.

PE comes in a few forms there is LMWPE which is used in your plastic shopping bags and then there is the stuff we use in climbing which is UHMWPE as 20kn said above lots of people sell UHMWPE as soft goods under many brands names dyneema and sprectra being the most recognizable to us.

Polyester is actually slighty weaker than Polyamide only just but good polyester has a tenacity of 7gm/den where as load bearing nylon is over 7.5gm/den and up to 8.5gm/den but despite the lower tensile strength it appears to be quite a bit more abrasion resistant i wish i could find it but i saw a abrasion test with polyester vs nylon ropes (for industrial uses of course) and polyester beat nylon hands down now of course construction of the rope will have a large part to play but the polyester really did wipe the floor with the nylon ropes. Polyester absorbs 0.4% of it's weight in water where nylon it's as much as 5% nylon is well know for getting weaker when wet where as polyester as far as i'm aware doesn't have the same issue so allot of caving ropes are polyester. Nylon is significantly more elastic than polyester with polyester while not completely static like dyneema it still has very low stretch and is used in super static ropes. Why are we seeing it in slings? No idea it's probably a bit cheaper to make and with better textile technology we are probably able to use polyester better.

That's all i know if anyone who has a formal education in textiles, material sciences or is in the industry would like to chime in it would be greatly appreciated.

that guy named seb wrote:

Polyester absorbs 0.4% of it's weight in water where nylon it's as much as 5% nylon is well know for getting weaker when wet where as polyester as far as i'm aware doesn't have the same issue so allot of caving ropes are polyester. Nylon is significantly more elastic than polyester with polyester while not completely static like dyneema it still has very low stretch and is used in super static ropes. 

That's all i know if anyone who has a formal education in textiles, material sciences or is in the industry would like to chime in it would be greatly appreciated.

Polyester is hydrophobic and has minimal loss of strength when wet.  I asked a friend in the industry about polyester static lines a few months ago and he said 'these will likely become more standard at some point once the wear cycles improve and durability catches up'. 

sfotex wrote:

Polyester is hydrophobic and has minimal loss of strength when wet.  I asked a friend in the industry about polyester static lines a few months ago and he said 'these will likely become more standard at some point once the wear cycles improve and durability catches up'. 

I think the main problem with polyester cords is they are stiff and the handling is rough. If that could be overcome with some new way of creating the fibers then I think polyester static lines could be really great. 

Static ropes designed for canyoneering (used for rappelling only, in wet/sandy conditions)  are usually 100% polyester.

Ryan Hamilton wrote:

I think the main problem with polyester cords is they are stiff and the handling is rough. 

When it comes to nylon vs polyester, I think the knotability and handling is more a function of their construction and intended use than the actual material. Cordage made with double-braid kernmantle construction tends have a lot softer hand, and is much easier to knot and work with, even in polyester. 

eg, Yale Blaze/Bandit is an all-polyester 11mm arborist climbing line. It's significantly softer and more knotable compared to the all-nylon PMI EZ-Bend. 

Bluewater accessory cordage is either nylon/nylon or poly/nylon (Cordelette). They're both much stiffer than all-polyester accessory cordage from other manufacturers. 

If the rope is stiff, it's because of a compromise vs other desirable properties - eg, tight sheath for abrasion resistance, or reduced elongation. 

Brian Abram wrote:

Dyneema is high modulus polyethylene 

D'oh!  I knew that, and I forgot that Dyneema is simply a brand name for UHMWPE.

Given that Petzl has slings that they specifically identify as Dyneema (https://www.petzl.com/CA/en/Sport/Anchors/ST-ANNEAU) I'm guess that this Pur Anneau is a non Dyneema branded material so Petzl is simply calling "high modulus PE"

Thanks for all the info, everyone!

And BIG THANKS to 20 kN and Ryan for filling us in on the properties and benefits of polyester! It sounds like Petzl made the right choice in going with polyester for some of their dog bones.