What are the different types of rope fibers?

Broadly speaking fibers can be divided into two categories - natural and synthetic. Most ropes today are made from synthetic fibers because they offer far superior performance in terms of strength and durability. Natural fiber ropes have a tendency to deteriorate as a result of rot and mildew, particularly if stored improperly. Natural fiber ropes should not be used in life critical applications.

All ropes deteriorate to various degrees from exposure to UV rays from the sun and other sources such as fluorescent lights. Many synthetic fibers have UV stabilizing agents added to improve UV stability. Ropes are also susceptible to damage from exposure to chemicals. Their chemical sensitivity and compatibility depends on many factors including temperature, period of exposure and concentration of the offending chemical. It is frequently not possible to readily identify the chemicals to which a rope is exposed and so testing may be necessary to determine compatibility. For example oil may contain numerous additives and, without knowing what they are, it could be impossible to know what effects the oil would have on rope.

Nylon is an excellent all around rope fiber, as it combines high strength with durability. Nylon ropes are not damaged by moisture, however, their strength is reduced when wet. Nylon ropes have excellent shock absorbing capability. They are impervious to rot and mildew but may be damaged by some chemicals, particularly acids. Nylon ropes will shrink when exposed to elevated temperatures. Nylon has a melting point of 250°C (482°F) but will lose strength well below that temperature. Better quality ropes are normally made from UV stabilized nylon.

Polyester looks and feels much like nylon, however, it has considerably less elongation and does not have increased elongation when wet. Polyester ropes are unaffected by water and are impervious to rot and mildew. They are more resistant to acids, but are sensitive to alkalis. Polyester is naturally quite UV resistant. Its melting point and performance at elevated temperatures are comparable to nylon.

Polypropylene is the least expensive of the common rope fibers. It is very light and therefore is often used where floatation is required. It is unaffected by water, and generally has good chemical stability. However, it is considerably weaker than nylon and polyester, and tends to deteriorate rapidly from UV radiation. Polypropylene ropes have a low melting point, and tend to exhibit high creep (gradual elongation under load).

POLYSTEEL is a copolymer fiber made by combining polypropylene and high-density polyethylene. It has many of the same characteristics as polypropylene but is about 80% stronger. It represents an economical alternative to polypropylene where increased strength is required.

Kevlar is stronger than steel when compared weight for weight. It has almost no stretch or creep, and can withstand very high temperatures (it decomposes at about 800°F). However, it has poor shock loading qualities, resistance to UV radiation and resistance to abrasion. It is therefore usually covered by another fiber when used in rope applications. Kevlar fibers are brittle and therefore Kevlar ropes loose strength when bent over small radii or where knots are tied.

Spectra is also a high strength fiber. It has low heat resistance, and a low melting point. It is very lightweight, and can therefore be useful where floatation is required. It has virtually no stretch, but has good shock loading qualities. It is rather slippery and therefore has poor knot holding characteristics. It suffers from creep, but has very good abrasion resistance.

Cotton is a soft fiber with exceptional handling and knot tying characteristics. It is a natural fiber and therefore has environmental benefits, however, it is susceptible to deterioration from moisture, rot and mildew.

Manila ropes are made from fiber obtained from tropical plants belonging to the banana plant family. They are the strongest of the natural fiber ropes, but have a limited storage life. Moisture, rot, mildew, and some chemicals will damage them. Manila ropes have rough handling qualities, but hold knots well and have relatively low stretch.

Hemp is also a natural fiber. It is softer than Manila to handle, however, it is considerably weaker. As with other natural fibers, it is easily damaged by moisture, rot and mildew.

Jute is a soft fiber but is not very strong. It is most commonly used for twines and smaller cordage.