Mammut slings question

[crackers]

Spectra and Dyneema are both HPPE, but they are not the same.

 

Uh, I'm not sure where you got this tidbit, but I'm willing to say its totally wrong.

 

Dyneema is a chemical invented (and patented) by DSM. They licensed the polymer but not the manufacturing process to Honeywell. Honeywell has a license to sell Dyneema as "spectra" inside of the USA. Under great demand from the government in 2001, DSM built a huge plant in NC to make Dyneema in the USA because Honeywell's production process was not and is not as efficient as the gel spinning done by DSM.

 

I buy Dyneema, not a lot, but enough to have had several conversations with DSM about the stuff.

 

And the people who I know who make kites and parachutes agree with me in that it has nothing to do with the material, abrasion resistance has to do with the size of the drawn fiber...both DSM and Honeywell make a large number of stock sizes now.

[still_climbin]

However, the melting point is much lower than Nylon. HPPE begins to lose strength at temperatures in the low 200's. So anything that causes friction against the sling can exceed this fairly quickly.

You're right on with this point. Be concerned with any friction application with Dyneema because melting will easily occure. Years ago while teaching climbing instructors in the military I saw an idiot trying to copy my team, who were using 1" nylon tubular web for rappelle harnesses, by purchasing look-alike polyethelyne webbing to make a harness. About 20 feet from the ground on a 120 ft. helicopter rappelle the binner he was using melted through his harness. Somehow he only broke his wrist. Dumb!

 

Polyethelene (and Dyneema/Spectra) melts at about 300 F while other tech fibers like Technora (modified aramide) and aramide (Kevlar) melt at about 930F. Nylon melts in the 480 F range.

Edited April 25, 2006 by still_climbin

[olyclimber]

I asked the Internet, and this is what some random person thinks:

 

"Both ‘Spectra’ and ‘Dyneema’ are HDPE (High Density Polyethylene) fibres. However, Dyneema (Manufactured in Europe and Asia by Toyobo/Dyneema, DMS), is recognized as being of a slightly ‘lower quality’ than the American version "Spectra". (The quality of Dyneema generally is very good). Also, the individual filaments that make up a Dyneema yarn are smaller than individual fibres in a spectra yarn; this translates to better abrasion resistance."

 

I should warn you that the Internet has been wrong before.

[PaulB]

It is also interesting to note that Spectra and Dyneema are much more resistant to UV than Nylon.

These informal test results show that loss of strength due to UV exposure varies, and that nylon does not always fare worse than Dyneema. Granted, it's a small sample size.

 

They licensed the polymer but not the manufacturing process to Honeywell

As a Honeywell employee, my corporate programming compels me to point out that Spectra was originally licensed to AlliedSignal, which bought Honeywell in 1999.

Edited April 26, 2006 by PaulB

[catbirdseat]

My understanding is that UHMWPE doesn't have any natural resistance to UV light. Various coatings are applied to protect it.

[daylward]

My understanding is that UHMWPE doesn't have any natural resistance to UV light. Various coatings are applied to protect it.

 

Okay, upon further pestering with Google, the Internet seems to vaguely imply that [uHMWPE (Ultra-High Molecular Weight Polyethelene) = HPPE (High Performance Polyethelene) = Spectra = Dyneema] has a high natural resistence to UV - roughly equivalent to that of Nylon. Apparently Nylon is considered to have a high UV tolerance, at least when compared with other synthetic organic fibers, like Kevlar, Vectran, and Technora. Clearly, even so, Nylon is far from immune to UV - but I retract my statement about Spectra being decisively better in that respect.

 

One rumor I had also heard was that Spectra/Dyneema weakens with flexing. I found at least one study that showed that not to be the case for Spectra/Dyneema, whereas it is strikingly true for other fibers such as Technora, Vectran and Kevlar.

 

http://www.amga.com/ComparativeStrengthTest.pdf

 

Note that this study did not have a pure Spectra cord included, but rather cords that were a mix of nylon & Spectra, but it leaves me with the strong impression that Spectra is very similar to Nylon in its ability to withstand flexing.

[catbirdseat]

I know that in the sailing world it didn't take long for sailmakers to discover that kevlar did not like the over and under that was typical of woven cloth. The fibers quickly broke down. They found they could laminate tapes made of linear fibers to a mylar sustrate. The Kevlar was much happier in that arrangement.

 

When it came to cord, the solution was to mix Kevlar with other fibers so as to separate them from each other. This was done first with polyester and then with Spectra. This mixed type was quite successful. It was extremely strong and low stretch (good in sailing, bad in climbing), durable, and could be spliced. The other strategy was to arrange them in a bundle of parallel fibers (difficult to splice).

 

I still have a pair of 60 ft 1/4 inch spinnaker sheets that are made of this mixed material. They are rated at 3,600 lbs and I've used them on boats up to 37 ft as light air sheets. They are murder on the hands when the wind gets up. Just put lots of wraps on the winch.

[still_climbin]

Dayl, I've been looking for an objectinve comparison like your reference. Thanks.

[billcoe]

Mammut rep said:

I have no idea if it is safe to mark your slings that way. In fact, I don't think I've ever seen anyone mark their slings before. I would say don't do it.

 

I take a magic marker and put a date on mine. It's shocking how fast time goes, and one day you're sitting there squinting to read a faded date on one of your newer slings which you vaguely remember thinking is a fairly recent purchase, and realize with a big assed hard-rain fu*cking jolt that '92 was actually ,ummmmmmmmmm 2006-1992 = Uhhhh, like 12-14 years ago or something close to that.

 

Shocking.

 

Rep, that was great info, a late thanks to you sir.

[cdurf]

I like the double shoulder length sizes. When I triple them for runners they are so clean and lay flat. I'm not going to use them from my shoulder legnth size though. I can't get a different color for color coded lengths. And I use the shoulder legnths for Bachmans and other stuff.

[Jens]

When are the newest even skinnier mammut slings coming out?

[catbirdseat]

Which ones? Even skinnier than 8 mm?

[IceIceBaby]

yep the 6mm