As far as I can tell, printing UHMW-PE is impossible.
UHMW is made using a special annealing process where it is cast and kept at a very specific temperature for an annealing cycle of sorts while in the presence of a catalyst. This causes the polymer to do a lot of linking and go from standard PE to what we call UHMW.
If you heat up UHMW-PE you kill those super long chains and end up with plain old PE again - which is a bit rubbish.
You might look into one of the Taulman Nylon grades as an alternative.