Page 25 - The Pocket Guide to Outdoor Knots

ranks below nylon and Terylene in terms of cost and performance, but it is the
most versatile of the synthetic fibers, and large quantities are made and sold at

reasonable prices for domestic, industrial and sporting applications not requiring
an exceptional performance.

Miracle fibers

Kevlar™ is an organic polymer (used for bullet-proof vests), which was
discovered by Du Pont in 1965 and is the lightest of today’s state-of-the-art
fibers. Weight-for-weight it is twice as strong as nylon, and has less stretch than

Terylene or Dacron. Advertising copy-writers have been tempted to compare it

favorably with the strands of a spider’s web. It is not that good. When a fly hits
and tangles with a spider’s web, it is equivalent to one of humankind’s fishing

nets withstanding the collision of a jumbo jet. Even Kevlar cannot cope with
such an impact. It is so brittle that merely bending and flexing its fibers causes

them to cut through one another, and ropes often consist of a Kevlar core
sheathed in a protective braid of polyester.

Dyneema™ from the Far East, and its US counterpart HMPE (High
Modulus Polyethylene), is marketed as Spectra™ by Allied Chemicals who

began making this super-lightweight polyethylene in 1986. It is more tolerant of
flexing than Kevlar, which it looks set to supersede.

Vectran™, is another high performance cordage produce, a thermoplastic
multifilament yarn spun from liquid crystal polymer with a complete absence of

stretch and—unlike Kevlar—with the ability to bend around tight radii.
PBO (Poly(p-phenylene-2,6-bezobisoxazole)) is yet another of these

remarkable fibers, up to 20% stronger than either Vectran or HMPE.

Summary

Both nylon and terylene rate highly in terms of handling, durability, resistance to

abrasion, rot and mildew, or exposure to alkaline chemicals. Nylon is more
easily damaged than Terylene by contact with acid and its life is rendered

significantly shorter than that of terylene by photo-chemical degradation through