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On 10-sep-04, at 16:26, Niclas Runarsson wrote:
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I just read a very interresting article about new-age tying thread in Fly
Fishing and Fly Tying. The author was a guy by the name of Christopher Helm.
Is this the same guy?
You bet! Chris uses nothing but GSP (gel-spun polythene) thread these days.
However, there is nothing very new about the material. GSP is good old polyethylene, but spun in a sort of innovative way. It was known for a very long time that intrinsically, carbon-based polymers are much stronger than steel, tensile-wise, the difference being that when stretched, metals only depend on metal-to-metal (sort of vanderwaals interaction, only somewhat stronger) interatomic bonds, whereas a carbon polymer can rely on covalent atom-to-atom bonds within the molecule -- mucho stronger. The problem with polymers has always been that while the intramolecular bonds are very strong, the overall strength of materials made from polymers depend as much on the interactions BETWEEN the polymer molecules as on the intramolecular bonds.
One solution to this was the aramide fiber (TWARON, KEVLAR), in which the polymer molecule includes rings that help align the molecules in a linear fashion, maximizing intermolecular interaction, as well as increasing that interaction itself. GSP (spiderwire, dyneema, etc.) uses another trick, namely to spin the polymeric material into a filament, then stretching the filament under partial melting; this induces the individual polymer molecules to stretch and align with one another, rather than coil up and align randomly. Again, this maximized intermolecular interaction, and greatly increased the tensile strength of the fiber. One drawback of PE (GSP, dyneema, etc) to aramide is its low melting point. Not only can it not be used under elevated temperature conditions, but it will also weaken dramatically in applications where the use itself generates heat, such as applications in which friction of a moving rope over a stationary object heats up the rope.
For tying bass bugs and pike flies, GSP rules...
Henk
==========================Heisenberg was right!======================== | Dr. Henk J.M. Verhaar | | | Environmental Fate and Ecotoxicology Specialist | | Fly Tier | web: www.xs4all.nl/~flyrod | | Stichts End 17 | e-mail: [EMAIL PROTECTED] | | NL-1244 PK Ankeveen | phone: +31 35 656 2128 | | the Netherlands | ICQ: 15727113 | ==========================Uncertainty happens!=========================
