Rope: Difference between revisions

'''[[Synthetic fiber]]s''' in use for rope-making include [[polypropylene]], [[nylon]], [[polyester]] (e.g. [[polyethylene terephthalate|PET]]), [[polyethylene]] (e.g. [[Dyneema|Spectra]]) and [[Aramid]]s (e.g. [[Twaron]], [[Technora]] and Kevlar). Some ropes are constructed of mixtures of several fibres or use co-polymer fibres. Ropes can also be made out of [[metal]] fibers. Ropes have been constructed of other fibrous materials such as [[silk]], [[wool]], and [[hair]], but such ropes are not generally available.

[[braid|Braided]] ropes are generally made from [[nylon]], [[polyester]] or [[polypropylene]]. Nylon is chosen for its elastic stretch properties and good resistance to [[ultraviolet]] light. Polyester is about 90% as strong as nylon but stretches less under load, is more abrasion resistant, has better UV resistance, and has less change in length when wet. Polypropylene is preferred for low cost and light weight (it floats on water).

There are many different kinds of braided line. Double braid line has an outer and inner braid that may be of the same or different material. Single braid has no core at all. [[Kernmantle rope]] has a core (kern) of long twisted fibers in the center, with a braided outer sheath or mantle of [[weaving|woven]] fibers. The kern provides most of the strength (about 70%), while the mantle protects the kern and determines the handling properties of the rope (how easy it is to hold, to tie knots in, and so on). In dynamic climbing line, the core fibers are usually twisted, and chopped into shorter lengths which makes the rope more stretchy. Static kernmantle ropes are made with untwisted core fibers and tighter braid, which causes them to be stiffer in addition to limiting the stretch.

'''Plaited rope''' is made by braiding twisted strands, and is also called ''square braid''. It is not as round as twisted rope and coarser to the touch. It is less prone to kinking than twisted rope and, depending on the material, very flexible and therefore easy to handle and knot. This construction exposes all fibers as well, with the same drawbacks as described above. '''Brait rope''' is a combination of braided and plaited, a non-rotating alternative to laid three-strand ropes. Due to its excellent energy-absorption characteristics, it is often used by arborists. This type of construction was pioneered by Yale Cordage.

Rope made from [[hemp]], cotton or nylon is generally stored in a cool dry place for proper storage. To prevent kinking it is usually coiled. To prevent fraying or unraveling, the ends of a rope are bound with twine, tape, or heat shrink tubing. The ends of plastic fiber ropes are often melted and fused solid. If a load-bearing rope gets a sharp or sudden jolt or the rope shows signs of deteriorating, it is recommended that the rope be replaced immediately and should be discarded or only used for non-load-bearing tasks.

A piece of rope that has a specific purpose is called a line, especially in nautical usage. Examples include clothesline, chalk line, anchor line, stern line, fishing line etc.

*Hearle, John W. S. & O'Hear & McKenna, N. H. A. ''Handbook of Fibre Rope Technology'', CRC Press, 2004