Re: [VFB] Scrounged Stuff for Fly Tying

[Henk Verhaar]

On 15 Nov, 2006, at 10:37, Pierre Bombardier wrote: Actually Henk, the fibers are no more linear in Dyneema or Spectrfa than they are in standard HDPE. The real diffference is that the molecular weight (length) of the polyethylene is much greater forming what is know asd Ultra-High Molecular Weight Polyethlene (UHMWPE).  The fiber is then made by ultradrawing afiber that has just been extruded which greatlyy increases the percent crystallinity in the fiber which is 'the same' as saying that the fibers are linear (or actually that the individual polymer molecules are isotropic and oriented along a common axis, the long axis of the fiber). I thought that by saying it thus, it would make sense to most people here.  Point remains that the purpose of the stretching is to maximize vanderWaals interaction between the polymer molecules. , greatly increasing the strenght.  There is still plenty of amorphous section in the fiber rendering it still very flexible.  One of the few plants in the US that has the capabilities for making UHMWPE is located here in then Lake charles, La area wheree I live (been sold a bunch of times, was Himont, then Montell, and now Basell , respectively joint ventures of Hercules-Montedison, Montedison-Shell, and now BASF-Shell). Undrawn UHMWPE is processed only by machining, as it is not amenable to regular polyethylene processing techniques.  Too viscous and too high a glass temperature? Cheers Henk =============================== ><(((((º> =============================== | Dr. Henk J.M. Verhaar             | e-mail: [EMAIL PROTECTED] | | Ecotoxicoloog en vliegbinder      | tel:    035 656 2128              |  | Stichts End 17                    | mobiel: 06 26 136034              | | NL-1244 PK Ankeveen               | web:    www.xs4all.nl/~flyrod     | =============================== <º)))))>< ===============================