RE: [VFB] Scrounged Stuff for Fly Tying

[Pierre Bombardier]

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, 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. 

Mark Delaney

Reuven Segal <[EMAIL PROTECTED]> wrote:

Henk:

 

You may have been trying to confuse me there with the description, but sadly I understood everything......damn engineers!!

 

R

 

______________________________________________

Reuven Segal

 

B. Engineering (Aerospace)- Final Year

B. Engineering (Manufacturing Systems and Management)

RMIT University

 

5/11 Rockbrook Road,

East St. Kilda, 3183

Melbourne, Victoria

Australia

 

[EMAIL PROTECTED]

Mobile: 0422 266798

 

-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]On Behalf Of Henk Verhaar
Sent: Wednesday, 15 November 2006 7:28 PM
To: vfb@troutnet.com
Subject: Re: [VFB] Scrounged Stuff for Fly Tying

On 15 Nov, 2006, at 9:13, Reuven Segal wrote:

What is Tyvek?

A nonwoven fabric from plastic fibers, used for tear-resistant envelopes as well as for building wrap during construction. It is a DuPont trade name. The fibers are 'standard' polyethylene, bonded by heat.

FYI, dyneema, spider wire and the likes are also polyethylene, linearized to massively increase the tensile strength of the fiber (linearization seeks to have the tensile strenght of the macroscopic fiber approach the chemical bond strength of the polymer molecule, by maximizing the intermolecular (vanderWaals) forces).

Dyneema has a higher tensile strength than Kevlar, but suffers from inferior heat resistance. It is therefore less well suited for high-friction uses.

Henk

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