Dyneema is a material invented in 1963 and now produced by the Dutch company "DSM" (Koninklijke DSM Naamloze vennootschap. "To this day we continue to use the English translation of the company's original name, the 'Nederlandse Staatsmijnen, Dutch State Mines', signifying both our heritage and how far we've come in just over a century."). Got that?
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Dyneema is made from ultra high molecular weight polyethylene.
What?
Ethylene is a simple organic chemical (C2H4). Cram it together with water in the right way and you have ethanol, or drinking alcohol (unless you're an ultralighter, in which case you don't drink it but only burn it in your stove to cook noodles for lunch.)
Polyethylene is a chain of ethylene molecules, a polymer. (Poly, get it? Many, much, multi, more, poly. Plus mer, a repeated unit. Polymer: Many mers, or many, many small molecules linked together into gigantic ones.) So there we have it.
Dyneema exists as a bunch of superlong polyethylene chains. Super super super long polyethylene chains. They are very tough too. This helps to make Dyneema resistant to most chemicals, to UV radiation, and to micro-critters that might try to munch it. In other words, Dyneema is hard to kill just like ordinary old polyethylene, the stuff clear plastic bags are made of, but Dyneema is tweaked, of course.
Officially, Dyneema is known as "High Modulus Polyethylene" or "HMPE", which, if you look that up, takes you back to "ultra high molecular weight polyethylene", which is about where we started with this definition. Big help there, right?
You might also see "HDPE" instead of "HMPE". HDPE stands for "High Density Polyethylene", but you don't need to care, really. Though now you know, in case you are ever asked. Welcome to the club, kid.
OK, so back to the real world. This polyethylene stuff doesn't absorb water or even easily get wet. Likewise, it feels slippery. It's so slippery that a Dyneema cord won't hardly hold a knot even if you put one there. So what's it good for then? Well Dyneema is used in webbing, specialized rope and cordage like ship's hawsers, for body armor, and in making a ripstop fabric called Dyneema Gridstop, something that is used in packs and is loved by backpackers, who are always on the lookout for the next unicorn of fabrics, so maybe you've heard of it already.
That Gridstop, as used in packs, isn't all Dyneema though, just some of it is. You can easily see the Dyneema part — it's the reinforcing threads, which show up white. They show up white because Dyneema, like Spectra (another miracle material), is impervious to dyeing. (Dyneema and Spectra are actually just two brand names for what is almost exactly the same thing.)
Dyneema is gnarly, seriously gnarly, and currently holds the world record as the strongest synthetic fiber in existence, at eight to 15 times the strength of old-fashioned steel. It's also 40 percent stronger than aramids, also known as ye olde "aromatic polyamides" (Kevlar for example), and has twice the cut resistance of aramids.
Spectra, to get back to that for a moment, is also less strong somehow than Dyneema, at up to only 10 times the strength of steel, max, or so they say. What is more, Dyneema (in case you were wondering, and definitely unlike steel), is light enough to float, while continuing to exhibit a fierce resistance to many chemicals (such as water, a common chemical found almost everywhere in nature) that is way beyond steel's as well.
Elsewhere in the commercial world, Dyneema has been sneaked into climbing equipment, shoes, and luggage, as well as many other mostly ordinary things.
Though all of the High Modulus Polyethylenes have a lot of strength for little weight, no matter what they're called, they do have a seriously weak spot — they melt at relatively low temperatures. What's low? Somewhere between 266° to 277° F (130° to 136°C), for Dyneema, which hardly rates a woot, so we won't give it a woot. Not here, and not now, for sure.
So, what else if anything?
Well, while all these HMPE/HDPE variants could easily be made into a much wider range of fabrics because humans are clever and capable of such achievements, the chemical makeup of this stuff, with its extremely long molecules of almost inert substances, produces a slippery feel that gives people creepy feelings if it's used in clothes for example, so it isn't used in clothes, although Dyneema could make your underwear bulletproof.
Something to think about.