Cords and ropes made from UHMWPE fibres (1), ( Dyneema, Spectra and the like), are very slippery, and the manufacturers that produce them - with no exception - advise the use of the triple fisherman's bend [aka double grapevine -dl*].
One should be specific, here. I presume that the cordage at issue
is the narrow segment of rockclimbing / caving / <etc.> kernmantle
rope users, with the typical (if not universal) material being a 5.5mm
cord with HMPE fibres only in the core. (Actually, there are some thicker,
"main" ropes used for canyoneering that have, IIRC, hi-mod fibres in
both the mantle & the kern (Technora, also to HMPE (Dyneema/Spectra));
but such ropes are not typically knotted together, in any way.)
This is in contrast to ropes made entirely of the fibres, such as can
be found in yachting and some other, commercial applications
(where knots are simply advised against).
What can happen in these ropes with the slippery (and no-stretch/static)
core fibres is that the core slides
within the sheath, leaving load-bearing
to the latter, and weakening the knot, thus. On rupture of the sheath,
it has been seen that the core just then pulls out of the knot,
like snake shedding its skin. (!)
Of course, any sufficiently convoluted bend would do the job,
If the job is merely staying tied, yes, this is likely.
But typically such cords are tied end-2-end to form slings,
and the knot can see some incidental knocking/sliding about,
where abrasion resistance is wanted. Also, these knots are
pretty much considered permanent, and the knot should be
secure when slack, even jamming. Not every convolution
of cordage will meet these criteria.
I have played with some easy-to-tie bends, ...
I can not tell if they offer any improvement over the "standard" double grapevine bend
...
I can tell you that none of these presented end-2-end knots
(and note that each image shows TWO possible such knots,
as you do not specify which ends are to be loaded (well, make
that THREE, if we include
offset loading!) )
satisfactorily yields compactness and abrasion resistance
like the
dbl.grapevine --and likely they're weaker.
It is odd to see you present a traced
strangle knot ,
as that knot is the component in the
grapevine bend which
is the end-2-end joint presumed dubious in this material!
With the slightly broader curves of the loaded strands of this
traced knot, I'd expect the security to be
less, not more.
An end-2-end joint I'd like to see tried is some version of
the
blood knot.
--dl*
====