This article takes an in depth look at high strength ropes.
This will cover topics such as:
Rope is a collection of strands, fibers, piles and yarns joined together to form a strong and a large structure. These strands or fibers are either twisted or braided with one another to give high tensile strength to the rope. The higher the tensile strength, the stronger a rope is. High strength ropes are also used in lifting and dragging purposes. Ropes were used by mankind since prehistoric times for different purposes such as tugging, hunting, climbing, securing things, fastening, and carrying things. In ancient times, natural fibers were used to construct ropes. In the 1950s, synthetic fibers started to be used in rope making. There are two types of high strength rope. These are natural and synthetic rope.
Natural ropes are made from natural products that are environmentally friendly and do not cause any harm to the environment from the byproducts of the rope making process. Some natural fibers are cotton, hemp, sisal, or other naturally found fibers. If the manufacturer chooses to blend natural with synthetic fibers in rope making, this will result in a stronger and more durable rope. Natural fiber rope is very strong when used, but can be damaged easily if exposed to water, mildew, molds, or UV light. The natural rope is not affected by high exposure of heat and can only be burnt if there are actual flames present. Natural fiber rope is affected by water exposure and cannot go back to its original shape and size if it shrinks. This can affect its use in certain fields, whereas natural rope is good for fastening objects because of its non slippery properties.
Synthetic fiber rope is made from synthetic or manmade materials such as nylon, polyester, polypropylene and multiple other synthetic materials. Synthetic ropes are stronger and last longer than that of natural fiber. Their average life span is about 30% more than that of natural fiber rope. Wet environments can’t cause damage to these ropes. Another beneficial aspect is that they are not prone to damage from mildews, UV light, or mold, making them useful in an open atmosphere. Synthetic ropes do not perform well when exposed to heat because it will melt these ropes. They are not environmentally safe because of harmful by-products emitted in the atmosphere during the production process. But they are strong and can be used easily for lifting or towing purposes.
High strength ropes come in different types of construction depending on the style of twists or braids of the rope. These are categorized and named on the basis of their construction. Each of the rope style is discussed below:
This rope is commonly called a solid braid and it is made by braiding the rope rather than twisting it. It is very strong because the braids are interlocked with each other to give a firm look and strength. It is a good choice for heavy pressure or weight of an object to be pulled or lifted. These are mostly used in pulleys or blocks due to durability because of their braided construction. Single braid rope is different sizes ranging from 8-12 strands per rope to even 8 plaited ropes.
This rope is also called a square braid and it is coarser in touch than other twisted ropes. There are about four sets of different strands that are present. These strands are twisted and wound around each other to form a braid type structure. These types of ropes are very flexible and strong, and can be easily knotted. One problem that arises in these ropes is that they are all twisted around the core and hence all strands are exposed to the environment. This makes them prone to damage easily.
Twisted rope, commonly known as laid rope, is the best one if there is a need to splice the rope. These ropes are made by coiling or twisting the strands together in the same direction. Three of the strands in these are coiled in opposite directions to each other to form a braid type structure to make it possible for a stronger grip. These ropes are generally less flexible and have a high chance of kinking if mishandled. These kinds of ropes are used in dock lines or for towing purposes.
Double braided rope is the best choice if strength and resistance are needed. This rope is made by coiling double braided strands on a double braided core. The double braided core and strands will give extra stability and flexibility to these ropes. Due to abrasion resistance, they are the best choice for marine environments but not a manufacturing site. Double braided ropes are very tough and don’t kink easily.
Hollow ropes are empty or hollow from the inside and can be spliced easily. It is a lightweight synthetic rope that can be used for ski towing and anchor lines because these are water resistant.
Diamond braid ropes are made by braiding the strands of fiber around the inner core carefully, tightly, and securely to ensure that the structure is firm and rigid.
These diamond braided ropes are more expensive than the other kinds of ropes because of its neatly and tightly woven structure, which gives a good look and durable structure to these ropes. These ropes are durable, round, firm, and can work well under stressful conditions. Diamond braided ropes can be easily spliced making them good to work with other kinds of ropes.
There are many different types of materials used in manufacturing high strength ropes with some of the popular ones discussed here. These are:
These are the types of material that are generally used in manufacturing high strength ropes. These materials are further categorized into different types, which will be discussed here in this chapter.
Aramid, also known as poly(para-phenylene terephthalamide), is a high strength fiber with a very low stretch in it and is resistant to high temperatures and creep. It is one of the first and best performance fibers that are used in rope manufacturing. Examples of it are Technora, Twaron, and Kevlar. This material has poor abrasion and UV resistance. It is best to wrap it in any other material such as polyester. However, meta aramids (Normex and Teijinconex) have high resistance to heat and abrasion, but the para linked aramids are stronger than meta aramids.
HMPE, also known as high modulus polyethylene, is a stronger material than aramids and it was an exotic material that was used tremendously in high strength ropes manufacturing. These are lighter than aramids with a density of 0.97 with common examples of this material as Dyneema and Spectra.
VECTRAN, also called aromatic liquid crystal polyester, is also a material of high strength. It is also a low stretch material like that of aramids and a resistance to heat.
Zylon is the market name for PBO. PBO is also called poly (p-phenylene-2, 6-benzobisoxazole)and is a new product introduced in the rope industry. It is a very strong material with low stretch and high resistance to high temperatures. Like aramids it needs to be protected from UV light and abrasions.
Polyester is the best synthetic material ever used in the rope industry. It is highly resistant to water, UV, and abrasions. These properties make this material a good choice for covering other materials’ braids to give them durability and resistance. The polyester material has a density of 1.38, a melting point of 260° C, and a breaking extension of 12%.
Nylon is a synthetic material also known as polyamide. This material is a bit stronger when it is in dry form compared to polyester. But when nylon gets wet, it is weakened by 10%. The abrasion and UV resistance of nylon are good but its stretch is best. It is stretchable up to 30% and thus it is best for pressure bearing situations. The relative density of nylon is 114, and its melting point is 220°C.
Polypropylene has floating properties because of its low density of 0.91. It is a light weight material and can float easily on water. Polypropylene bears a moderate UV and abrasive resistance. Its extension break is just like polyester though it is weaker than polyester. Polypropylene is also highly resistant to chemicals and has a melting point of 170°C.
Polyethylene is similar to polypropylene in many properties except UV resistance which is a bit better than polypropylene. Polyethylene has a relative density of 0.97 and its melting point is 165° C.
PEEK, also known as polyetheretherketone, is a polymer that belongs to the ketone family. The ketone family exhibits excellent dimensional and thermal stability along with high resistance to harsh chemical and abrasion conditions. The Zyex PEEK fiber is very well known for its ability to withstand high temperatures, chemicals, and heat.
Different types of ropes are made from these stated high strength fibers, which are used in many fields. Common examples of high strength fiber products are Kevlar, Twaron, Technora, Dyneema, Spectra, Polyester, and Nylon. These types will be discussed here.
Due to their strength, stiffness, hardness, and thermal stability, aramid fibers are the best option for many purposes. It is best to use for these characteristics, but the Kevlar rope is known for its low shock resistance property. If kevlar ropes are subjected to shocks, they can be easily damaged.
The chemical structure of Kevlar shows that it is a polar molecule and its long crystal structure contributes a lot in its strength. However, as Kevlar is a polar molecule, it can attract many chemical substances to bond with it, such as epoxy and water. These bonds are helpful in some circumstances but sometimes bonds with water can harm this rope by wetting it easily.
Kevlar fibers are inter-chained, and its high capacity to bond with other molecules gives aramids a unique combination of properties. The physical properties of Kevlar are:
Kevlar ropes are chemical resistant and lower in weight, so these are the best option to replace steel cables. But they can be degraded in the sun so a protective covering is necessary for these ropes. The core is made of aramid rope and the outer layer is of some UV resistant material such as polyester. Kevlar ropes are widely used in boating. For climbing purposes, these ropes are not considered reliable because of their inability towards shock loads. They can break easily without giving any warning signs and can be dangerous for climbing or other loaded activities. Kevlar ropes can replace steel in winches, the suspension bridge in Scotland and guy wires in hydro tower Kevlar ropes are used. They are highly resistant to heat therefore in many applications asbestos is being replaced by these aramid ropes.
High modulus polyethylene is also called high performance polyethylene (HPPE) and in the sailing and boating industry as Spectra and Dyneema.
The chemical structure of HMPE has long molecular chains with no groups attached to the molecule. This structure gives no space to other molecules attached to its site for any chemical attack. Its long molecular chain is very strong and can be stretched easily. HMPE doesn’t attract water molecules, any chemical or any microorganisms so they do not get wet or even stick to hands. Gel spinning is the process for manufacturing Dyneema and Spectra.
High modulus polyethylene is a great fiber because of its unique chemical structure and hence it depicts different characteristics or properties to it. These are:
HMPE is a strong fiber with a low weight which helps it to float on water. It has good abrasion, chemical, and UV resistance. HMPE is used in high performance sails and rigging in yachting. High performance polyethylene is also used in body armour clothing, vehicles, cut resistant gloves, climbing equipment, fishing lines, paragliding equipment, spear lines for spear guns and bow strings, parachute’s suspension lines, and many more activities. Spectra is also sometimes used in towing and winching. Due to being able to float, it is the best to use for marine towing.
Terylene, Dacron or Trevira are the commercial names of polyester fiber. Polyester fibers are used in boat lines and sailing because of the durability, flexibility and reasonable prices. Polyester fibers are very thin with a diameter of 0.023mm dia. They are white in color. Generally it is difficult to distinguish between nylon and polyester.
Polyester is the best synthetic fiber that is used for several applications where other fibers fail because of its good UV and abrasion resistance and also its stiffness. It is widely used in making sheets, sailing boats, and ropes that are used for mooring or winch lines. At high temperatures other fibers melt but polyester has a high melting point so this can be used easily in such circumstances. They act as good shock absorbers and also on blocks and capstans where low creep is necessary. Polyester is also used in protective layering of many other fibers such as aramids. These can be used for longer times in an outdoor environment without the fear of wearing off.
Nylon is a synthetic fiber also known as polyamide. It can be molded, spun, and machined. Nylon ropes are widely used in many fields and applications. The physical and chemical properties are given below.
Nylon is used in dock lines as it can be dyed in any color so fishermen dye it and place it on their docks to make it more aesthetically beautiful. Nylon nano filament has been used in fishing lines for many years. Anchor lines for most yachts are made of nylon. Paracord is a nylon string that is suspended with a parachute.
Zylon is the best synthetic fiber in the market nowadays with a high tensile strength and rigidity. The tensile strength of zylon is 1.6 times higher than that of Kevlar. Zylon can be found everywhere from tennis racquets to construction projects.
Zylon is widely used in making protective clothing because of its heat resistant properties. It is also used in the protective coating of certain wires and also found in cement for reinforcement purposes. Zylon is also found in the sports industry present in bike tires, tennis racquets, snowboards, yacht ropes and many more. Zylon is also used in cable cover material for welding machines.
Like Kevlar, Nomex is an aromatic polyamide. The Meta-Aramids molecular position is different to Para-Aramids in their linkage. The chemical bonding of Nomex is zigzag in composition, making it lower in tensile strength and rigidity. Nomex is an elongated fiber and is used best in making yarns.
Nomex fiber is really well known to be used in protective gears of firefighters, pilot crews, in industries for saving from flames and electricity. Cement and asphalt factories use filter media made of Nomex. Protective gears from Nomex can save from flames, electric currents and many other hazards.
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