Introduced in 1938, nylon is the first highly commercially successful artificial fiber. Man-made fibers are known as synthetic fibers. They compete with natural fibers such as manila (abaca), hemp, and cotton.
The primary reason that nylon is used in the fabrication of rope and hoisting slings, often referred to as chokers, is its strength. Nylon has two times the pulling strength of manila.
It's All About Little Chains
Textile fibers are formed by molecular chains; tiny little links bonded together, known as polymers. The number of chains and their individual bond strengths are directly related to the tensile strength of a fiber. Natural fibers are limited in their ability to naturally form strong bonds. On the other hand, synthetic fibers such as nylon, can be chemically made to form very long, strongly bonded molecular chains.
The word nylon is not capitalized nor does it carry the registered trademark symbol. Nylon was invented by the DuPont Company who in the 1930s held a disdain for anything trademarked. The company purposely did not apply for trademark registration in order to allow the world to use the term freely. Consequently, unlike later Dupont synthetics such as Dacron®, Tyvek®, and Kevlar®, nylon has become just another common word in all languages.
Nylon versus Natural Fibers
Natural fibers and natural fibers blended with synthetics enjoy respectable popularity in the apparel market due to their pleasing tactile feel and their appealing appearance. Strength, elasticity, abrasion resistance, and resistance to chemical attack are not major considerations in clothing. This is not so in the rigging industry. Nylon provides all of these attributes that are important to safe rigging. Also, nylon melts under high temperatures contrasted to natural fibers that burn.
Nylon versus Other Synthetic Fibers
While all synthetic textile sling materials are strong, lightweight, and very flexible, decisions on exact material selection is often based on elongation under load and chemical resistance. Nylon can stretch up to 10% of its initial length under rated load. This is contrasted to only 3% elongation for polyester. Nylon's greater elongation can be a positive if the absorption of a shock load is necessary. It can be a negative if little movement is desired during a lift.
Nylon is resistant to most regularly encountered chemicals with the exception of concentrated acids and bleaches. It is highly resistant to insects and fungi, as well as molds, mildew, and rot. While not usually a problem, prolonged exposure to sunlight results in UV degradation of nylon.