Agreed.nixmatters wrote: ↑Mon Sep 16, 2019 5:40 pmFinally someone with a good and logical explanation ^^^
The looser weave of Aluula is well visible and easy to count in the very first video leaked out by gleiten.tv.
And when we talk about puncture resistance, we need to clearly distinguish between
- puncture from fine 'needle like' object, normally causing small air leakage and easy to repair (patch the bladder)
- cuts in the material by glass, etc. causing material tear (if big enough)
- LE explosion caused by tomahawking the kite in water or on land.
In the first case I assume conventional dacron will be better. In the other 2 - the Aluula.
Dacron has a very tight weave and a melamine resin coating that makes it so stiff (esp. in bias), which is the very reason for its low tear strength. The resin matrix keeps the single yarns from slipping and they break one by one.
ALUULA on the countrary has a loose weave with (apparently) softer coating, which in the case of tear allows the yarns to shift/slip and act like a ripstop - clearly visible in the videos where people are trying to tear it with bare hands. Ironically, the more you try to tear it, the stronger it gets.
Aluula bias stiffness I assume comes from the high modulus of the yarn used, i.e. when warp and weave are tensioned (inflated LE) to the point where the residual elongation of the weave+yarn come close to its anyway low maximum (3% vs ~10% for HT polyester), the bias elongation of the relative open weave increases dramatically.
Graphene function in Aluula has nothing to do with fiber tensile strength, modulus or elongation. It is there to make the coating possible. Just a nano powder added to the liquid UHMWPE (I guess) before fiber extrusion (gell spinning).
I have no involvement in this development and haven't had a chance yet to see or touch the material. It's basic material knowledge and logic.
Also, HMWPE is very slippery, so even more than with polyester you'll need that coating to keep all the fibers in place. Coating does little for individual fiber strength, but it does add to cloth strength.