Datasheet

62
Radiation
Installed cable ties of various materials have been exposed to different amounts
of radiation to determine the maximum acceptable limit. These tests were
conducted by Panduit mainly to determine the acceptability for use in various
areas of nuclear power plants (accumulated over 40 year life). See Table B for
radiation resistance rating.
Moisture
Many plastics when exposed to high relative humidity absorb water and, as such,
the tensile strength of the material can change dramatically. Nylon 6.6 when
exposed to 100% relative humidity, will absorb as much as 8.5% water which will
reduce tensile strength by 50% when compared to a dry cable tie. Polypropylene,
HALAR
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, Type 12 Nylon, and TEFZEL
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are low water absorbing materials and,
as such, the effect of water is minimal. See Table B for moisture absorption.
Temperature
Plastic materials normally undergo property loss during exposure to high
temperature due to oxidation. The maximum temperature for successful service
depends upon the material used as well as environmental conditions. Initially,
plastics become more flexible and weaker when exposed to high temperatures.
After a period of time, oxidation may occur which will cause embrittlement,
making plastic cable ties more susceptible to failure from impact and vibration.
Low temperature exposure will also make most plastics more brittle during this
exposure, but little property loss occurs when the material is returned to room
temperatures. The minimum continuous use temperature after installation is
stated in Table B.
Tensile Strength
Most cable ties are selected based on material, length and minimum loop tensile
strength. Minimum loop tensile strength was established under Military
Specification MIL-S-23190. Each cross section cable tie (Miniature-M,
Intermediate-I, Standard-S, Heavy-H and Extra Heavy-EH) has a different loop
tensile strength when testing per MIL-S-23190.
The cable tie is first conditioned at 49°C (120°F), 20% relative humidity for 24
hours, then the cable tie is installed on a split mandrel and the halves of the
mandrel separated at a rate of 1" (25.4mm) per minute (Fig.1). The separating
force required to unlock or break the cable tie is the loop tensile strength. Loop
tensile strength is dependent both on the locking design and the tensile strength
(psi) of the material. As an example, the tensile strength of polypropylene
material is approximately 1/2 to 1/3 of nylon 6.6; thus the loop tensile strength of
a given cross section tie made of polypropylene would be much less than a tie
made of nylon 6.6. This is another property to be considered when selecting a
cable tie. The various representative loop tensile strengths are listed in Table B.
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HALAR is the Registered Trademark for Ausimont Inc. fluoropolymer
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TEFZEL is the Registered Trademark of E. I. DuPont Co., fluoropolymer
Radiation/Moisture/Temperature/Tensile Strength
Fig. 1