Cavechat.org

Hello everyone:

Does anyone know of any sources for data on thermal degradation of Nylon? I know it melts at 374-663F, but I'm curious if there has been a study on the weakening of rope before melting.

I've read that it's fine to use hot water (140F+) to clean ropes since such short time and a temperature so far below melting point is not doing any damage, but I'm having a hard time finding any scholarly articles that can verify this. Any sources of data or information you have on this would be greatly appreciated.

cavepaw wrote:Hello everyone:
Does anyone know of any sources for data on thermal degradation of Nylon?
I know it melts at 374-663F,
but I'm curious if there has been a study on the weakening of rope before melting.

Whoa! Where'd you get those temperatures?
What I'm looking at now** says 258^C for Type 6.6 & 218^C for Type 6,
which is 496 & 424^F, resp., per some on-line converter.

[** Handbook of Fibre Rope Technology ]

The book has some interestingly inconsistent assertions,
though : in one place (Table 12.3, p.253) is gives as the
Safe Working Temperatures (Long term : > 1 month)
60 - 50 - 60 (all ^C) for, resp., Nylon - Polyester - HMPE (!)
and short-term ("up to 10 minutes")
70 - 200 (!) - 80 .

(Quite surprised to see HMPE working safely at nearly
half-way to its melting point of 150^C !)

Elsewhere, there comes a general statement that
nylon & polyester should be limited to 90^C, and
HMPE 50^C. !?

Back to Table 12.3, it also gives ("Information from yarn
manufacturers and other sources") :
Approx. values (over 0 .. 50^C range)
drop in strength (modulus) per 10^C [rise, presumably]
for resp. as above ... 2.5% (3%) - 2.5% (3%) - 6% (4%).

*kN*

http://machinedesign.com/BDE/materials/ ... t2_29.html is where the Temperature data came from. It's a pretty large range depending which variant of Nylon is actually being used.

Those are pretty high values for temperature. 90C as the upper limit? If that's true then I'm impressed.
I bet manufacturers might have a safe operating range available too.

An exerpt from an article on rope care by Steve Hudson, President of PMI. Article can be foudn here. http://www.pmirope.com/news/blog3-9-10/

• Polyester: 275°F high temperature working limit
• Nylon: 250°F high temperature working limit
• Polyolefin (polypropylene, polyethylene): 150°-200°F high temperature working limit
• Aramids (Kevlar, Twaron): 350°F high temperature working limit
• HMPE (Spectra, Dynema): 150°F high temperature working limit