High strength fiber weakening - Nylon and Spectra

Spectra and nylon fiber


Feb 1993

After hearing many conflicting things, I decided to call Blue Water and ask them about nylon weakening with age. I asked to speak to someone about technical questions, and I was transferred to Phyllis.

She said that age is not a problem. I asked about a 10 year old rope stored under ideal conditions. She said it should be tested first, but that it should be ok.

I also asked about UV exposure. She fax-ed me some info, which I am reprinting (with her permission).

SPECTRA Technical Information

What is SPECTRA ? SPECTRA is, quite simply, the strongest fiber ever
made.  Pound for pound, it is ten times stronger than steel. SPECTRA
was developed by the High Performance Fibers Group of Allied-Signal
Inc. SPECTRA's extensive physical properties offer benefits that make
it ideal for chock cord and webbing applications.

SPECTRA is an ultra-high molecular weight polyethylene that exhibits
outstanding properties:

Low specific gravity                    High specific strength
Low moisture sensitivity                Excellent chemical resistance
High impact resistance                  High energy to break
High specific modulus                   High abrasion resistance
Excellent electrical properties

Outstanding Performance
    Excellent cut and abrasion resistance
SPECTRA high performance fiber offer unsurpassed cut resistance and
durability. SPECTRA is far superior to any high performance fiber in its
abrasion resistance. There physical parameters are responsible for this.

1) High tensile modulus - which gives the fiber a very high breaking
2) Low coefficient friction - causes the cutting edge to literally "slide"
   over the yarn construction inflicting a minimum amount of cut or
   abrasion damage.
3) High molecular weight fiber - yielding a large degree of structural
   integrity within the individual filaments.

Temperature Limit = 250 F
SPECTRA is a registered trademark of Allied Signal Inc
BLUE WATER is a registered trademark of Blue Water Ropes & Equipment.
Kevlar is a registered trademark of E.I. Dupont de Nemouis & Co.

Why Blue Water SPECTRA products?

a) Excellent Protection and Long Wear Durability. Far greater life span
   than other products.
b) Better Performance. More flexible, stronger, and lighter than other
c) Quality and safety. Blue Water has one of the finest quality control
   systems in the world which assures top, consistent quality in all Blue
   Water products.
d) SPECTRA Thread on all stitching. All bar tacks are stitched with SPECTRA
   thread to yield longer life and more abrasion resistance.

SPECTRA and Ultraviolet Rays

In a test of the effects of U.V. light on fibers in accordance with
AATC standards, samples of SPECTRA, Kevlar, Nylon, and Polyester were
subjected to 400 hours of direct exposure to U.V. rays. Figures listed
are percent of strength retention after exposure. As you can see SPECTRA
outperformed Kevlar in resistance to ultraviolet radiation.
                        SPECTRA Kevlar  Nylon   Polyester
Xenon Method 16E        72%     56%     91%     50%

Chemical Resistance

SPECTRA's polyethylene molecular structure makes it inert to chemical
reaction. The strength retention values obtained after 6 months immersion
is indicated in the chart.

Agent                           SPECTRA         Aramid*

Sea Water                       100%            100%
Hydraulic Fluid                 100%            100%
Kerosene                        100%            100%
Gasoline                        100%            93%
Glacial acetic acid             100%            72%
1M Hydrochloric acid            100%            82%
5M Sodium Hydroxide             100%            40%
Ammonium Hydroxide (29%)        100%            42%
Hypophosphite solution (5%)     100%            70%
Perchlorethylene                100%            79%
(10%) detergent solution        100%            75%
Clorox                          91%             0%

* The most common aramid fiber in the climbing industry.

[End of fax]

I have purchased some spectra fabric and some spectra thread. The thread is about 4 times stronger than nylon thread of similar diameter. It is quite expensive stuff. Fabric is roughly $34 per yard (50 inches wide) 3.1 oz/sq yard weight. It is quite abrasion resistant. I scraped both threads with an x-acto knife and looked at the results under a microscope. I haven't made anything yet, but I plan to.

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