On Oct 14, 2:22Â*pm, Martin Gregorie
wrote:
On Thu, 13 Oct 2011 19:18:12 -0700, Bill D wrote:
Martin, you must have had some really crappy rope mislabeled as Dyneema
. Â*The 12 strand hollow braid we use has 15x the abrasion resistance of
steel.

Well, it looked and felt like Dyneema/Spectra/whatever brand you prefer,
i.e. dead slippery to handle. As I said it was naked - just a fairly
loosely woven braid with a circular cross section that was sold as 80 lb
fishing line - I've seen the same sort of line and thickness in Dacron
but then, of course, it would have been around 18-20 lb line, say
somewhere between 0.3 to 0.5mm in diameter.

Since it felt so slick I was sure it would slide round the outside of
something as relatively large and smooth as 3mm brass tube, but nooo Â*-
the stuff had fluffed up before I even got the model out of my workshop,
so I replaced it immediately with Dacron, which worked as I'd expected
the Dyneema to do.

but Â* The off road 4x4 guys use it on their bumper winches with it
going over sharp rocks and trees. Â*I've never seen the problems you
describe.

But is that stuff naked or has it got a woven Dacron tube as its outer
layer? Obviously some of the stuff that was used as winch cable had such
an outer shell or the splicing method I saw described (threading one end
in and out of the casing with a big needle for 50cm or so) would never
have worked.

--
martin@ Â* | Martin Gregorie
gregorie. | Essex, UK
org Â* Â* Â* |

This is the stuff the 4x4 guys use - it has no sheath.
http://www.okoffroad.com/stuff-winchrope-atv.htm

Dyneema/Spectra/UHMWPE rope or whatever you call it has 15x steels
abrasion resistance, 10x steel's strength per weight and a friction
coefficient lower than Teflon plus a lot of other engineering
superlatives. It simply can't be beat as winch rope for 4x4's or
gliders. It does "fuzz up" as it wears but the fuzz actually protects
the rest of the rope.

Even this miracle material is being significantly improved.

"Abstract:
This paper reports the use of multiwalled carbon nanotubes (MWCNT) to
reinforce and toughen gel-spun ultra high molecular weight
polyethylene (UHMWPE) fibers. By adding 5 wt% MWCNT, ultra strong
fibers with tensile strengths of 4.2 GPa and strain at break of ∼5%
can be produced. In comparison with the pure UHMWPE fiber at the same
draw ratios, these values represent increases of 18.8% in tensile
strength and 15.4% in ductility. In addition, a 44.2% increase in
energy to fracture has also been observed. The mechanism of
reinforcement has been studied using a combination of high resolution
scanning electron microscopy (SEM) and micro-Raman spectroscopy.
Carbon nanotube alignment along the tensile draw direction has been
observed at high elongation ratios. Such alignment induces strong
interfacial load transfer both at small and large strains to enhance
the stiffness and tensile strength of the composite fiber.
Consequently, the mechanical properties of the composite fiber follow
closely with the rule of mixtures. Our work also reveals potential for
positive deviation from rule of mixtures if the CNT alignment can be
further optimized."