A cable tie is a type of fastener, for holding items together electrical cables or wires. Because of their low cost and ease of use, cable ties are ubiquitous, finding use in a wide range of other applications. Stainless steel versions, either naked or coated with a rugged plastic, cater for exterior applications and hazardous environments; the common cable tie made of nylon, has a flexible tape section with teeth that engage with a pawl in the head to form a ratchet so that as the free end of the tape section is pulled the cable tie tightens and does not come undone. Some ties include a tab that can be depressed to release the ratchet so that the tie can be loosened or removed, reused; the most common cable tie consists of a flexible nylon tape with an integrated gear rack, on one end a ratchet within a small open case. Once the pointed tip of the cable tie has been pulled through the case and past the ratchet, it is prevented from being pulled back; this allows several cables to be bound together into a cable bundle and/or to form a cable tree.
A cable tie tensioning device or tool may be used to apply a cable tie with a specific degree of tension. The tool may cut off the extra tail flush with the head in order to avoid a sharp edge which might otherwise cause injury. In order to increase resistance to ultraviolet light in outdoor applications nylon containing a minimum of 2% carbon black is used to protect the polymer chains and extend the cable tie's service life. Blue cable ties are supplied to the food industry and contain a metal additive so they can be detected by industrial metal detectors. Cable ties made of ETFE are used in radiation-rich environments. Red cable ties made of ECTFE are used for plenum cabling. Stainless steel cable ties are available for flameproof applications—coated stainless ties are available to prevent galvanic attack from dissimilar metals. PlastiCuffs are handcuffs based on the cable tie design and are used by law enforcement to restrain prisoners. Cable ties are sometimes used to prevent hubcaps from falling off a moving vehicle, some are sold for this purpose.
Cable ties were first invented by Thomas & Betts, an electrical company, in 1958 under the brand name Ty-Rap. They were designed for airplane wire harnesses; the original design used a metal tooth, these can still be obtained. Manufacturers changed to the nylon/plastic design; the design has over the years been developed into numerous spin-off products. One example was a self-locking loop developed as an alternative to purse-string suture in colon anastomosis. Ty-Rap cable tie inventor, Maurus C. Logan, worked for Thomas & Betts and finished his career with the company as Vice President of Research and Development. During his tenure at Thomas & Betts, he contributed to the development and marketing of many successful Thomas & Betts products. Logan died on 12 November 2007, at the age of 86; the idea of the cable tie came to Logan while touring a Boeing aircraft manufacturing facility in 1956. Aircraft wiring was a cumbersome and detailed undertaking, involving thousands of feet of wire organized on sheets of 50-foot long plywood and held in place with knotted, braided nylon cord.
Each knot had to be pulled tight by wrapping the cord around one's finger which sometimes cut the operator's fingers until they developed thick calluses or "hamburger hands." Logan was convinced there had to be an more forgiving, way to accomplish this critical task. For the next couple of years, Logan experimented with various materials. On June 24, 1958, a patent for the Ty-Rap cable tie was submitted. Self-locking loops are used for closure of the sternum after open chest surgery and at repair of rib fractures. Cable ties are viewed as single-use devices. However, if a closed loop needs to be opened again, rather than destroying the cable tie by cutting, it may be possible to release the ratchet from the rack. While some cable ties are designed for reuse with a tab that releases the ratchet, in most cases a sewing needle or similar object will need to be interposed between the ratchet and the rack. Ties reused in this way will be weaker than new ones. To open without cutting, the ratchet box can be crushed vertically using pliers.
Beaded cable ties: Unique beaded design allows them to be releasable and reusable Releasable cable ties: Easy to apply and remove, reusable Ladder style cable ties: For intermediate bundling and retail applications Identification cable ties: Built-in flags for written or printed identification Parallel entry cable ties: Tamper-proof, low profile heads Tear-off cable ties: Quick release design requires no cutting tools Pull-tight seals: Tamper-evident seals Steggel ties: Heavy duty, multipurpose ties Other methods of bundling cable together securely and semi-permanently include cable lacing, binding knots such as the surgeon's knot or constrictor knot, Velcro brand hook-and-loop strips, conveyor belt hooks, twist ties, Rapstrap fasteners, metal buckle clips or Cablox cable management. Cable dressing History of Cable Tie Cable ties patents
A shackle known as a gyve, is a U-shaped piece of metal secured with a clevis pin or bolt across the opening, or a hinged metal loop secured with a quick-release locking pin mechanism. The term applies to handcuffs and other conceived restraint devices that function in a similar manner. Shackles are the primary connecting link in all manner of rigging systems, from boats and ships to industrial crane rigging, as they allow different rigging subsets to be connected or disconnected quickly. A shackle is the shaped piece of metal used with a locking mechanism in padlocks. A carabiner is a variety of shackle used in mountaineering. With a larger "O" shape to the loop, this shackle can take loads from many directions without developing as much side load. However, the larger shape to the loop does reduce its overall strength. Referred to as an anchor shackle. Known as a chain shackle, D-shackles are narrow shackles shaped like a loop of chain with a pin or threaded pin closure. D-shackles are common and most other shackle types are a variation of the D-shackle.
The small loop can take high loads in line. Side and racking loads may bend a D-shackle; this longer version of a D-shackle is used to attach halyards to sails sails fitted with a headboard such as on Bermuda rigged boats. Headboard shackles are stamped from flat strap stainless steel, feature an additional pin between the top of the loop and the bottom so the headboard does not chafe the spliced eye of the halyard. A pin shackle is closed in a manner similar to a clevis, it is for this reason they are referred to, in industrial jargon, as clevises. Pin shackles can be inconvenient to work with, at times, as the bolt will need to be secured to the shackle body to avoid its loss with a split pin or seizing wire. A more secure version used in crane rigging features the combination of a securing nut located alongside the cotter pin. Pin shackles are practical in many rigging applications where the anchor bolt is expected to experience some rotation; as the name implies, a snap shackle is a fast action fastener which can be implemented single-handedly.
It uses a spring-activated locking mechanism to close a hinged shackle, can be unfastened under load. This is a potential safety hazard, but can be useful at times; the snap shackle is not as secure as any other form of shackle, but can come in handy for temporary uses or in situations which must be moved or replaced such as a sailor's harness tether or to attach spinnaker sheets. Note: When this type of shackle is used to release a significant load, it will work rather poorly and is to have the pin assembly or the split ring fail; the pin is threaded and one leg of the shackle is tapped. The pin may be captive, which means it is mated to the shackle with a wire; the threads may gall if overtightened or have been corroding in salty air, so a liberal coating of lanolin or a heavy grease is not out of place on any and all threads. A shackle key or metal marlinspike are useful tools for loosening a tight nut. For safety, it is common to mouse a threaded shackle to keep the pin from coming loose; this is done by looping mousing wire or a nylon zip tie through the hole in the pin and around the shackle body.
For pins that have a cross-hole in the threaded end a cotter pin can be used. One disadvantage of wire is that mousing can introduce galvanic corrosion because of material differences. Nylon is not recommended for use. A twist shackle is somewhat longer than the average, features a 90° twist so the top of the loop is perpendicular to the pin. One of the uses for this shackle include attaching the jib halyard block to the mast, or the jib halyard to the sail, to reduce twist on the luff and allow the sail to set better. Modern strong fibers such as PBO (IUPAC name: poly, ultra-high-molecular-weight polyethylene —or Dyneema and other synthetic fibers are used to make extra strong ropes which can be tied into lockable loops called soft shackle. According to sailmagazine.com "a soft shackle can handle just about every function performed by a metal shackle, in many cases better. Soft shackles articulate better, don’t rattle around when not under load, don’t chew up toe rails or beat up masts and decks, don’t hurt when they whack you on the head, are easier to undo and don’t have pins that fall overboard at a critical moment".
A modern rope can lift as heavy loads as a steel wire much heavier. When a soft shackle fails it is always at the diamond knot made of the strong slippery rope that sucks the tails in under heavy load. Edwards, Fred. Sailing as a Second Language. Camden, ME: International Marine Publishing. ISBN 0-87742-965-0. Hiscock, Eric C.. Cruising Under Sail. Oxford University Press. ISBN 0-19-217599-8. Marino, Emiliano; the Sailmaker's Apprentice: A guide for the self-reliant sailor. Camden, ME: International Marine Publishing. ISBN 0-07-157980-X
Rope splicing in ropework is the forming of a semi-permanent joint between two ropes or two parts of the same rope by untwisting and interweaving their strands. Splices can be used to form a stopper at the end of a line, to form a loop or an eye in a rope, or for joining two ropes together. Splices are preferred to knotted rope, since while a knot reduces the strength by 20–40%, a splice is capable of attaining a rope's full strength. However, splicing results in a thickening of the line and, if subsequently removed, leaves a distortion of the rope. Most types of splices are used on 3-strand rope, but some can be done on 12-strand or greater single-braided rope, as well as most double braids. While a spliced 3-strand rope's strands are interwoven to create the splice, a braided rope's splice is constructed by pulling the rope into its jacket. Back splice – A splice where the strands of the end of the rope are spliced directly back into the end without forming a loop, it is used to finish off the end of the rope to keep it from fraying.
The end of the rope with the splice is about twice the thickness of the rest of the rope. With nylon and other plastic materials, the back splice is no longer used. Cut splice – A splice similar to the eye splice, it is used for light lines where a single splice would tend to come undone, the rope being wet. It makes a strong knot. A cut splice is a join between two ropes, made by side splicing the ends apart, to make an eye in the joined rope which lies shut when the rope is taut, its original name was bowdlerised to "cut splice". Eye splice – A splice where the working end is spliced into the working part forming a loop. Ring splice – Attached the working end of a rope to a ring or clew. Chain splice – Attached the working end of a rope to a chain. Figure-eight "splice" knot- A splice-like bend knot used for joining two ropes. Horseshoe splice – A cut splice where the two sides of the loop are of unequal length. Long splice – A splice used to join two rope ends forming one rope the length of the total of the two ropes.
The long splice, unlike most splice types, results in a splice, only slightly thicker than the rope without the splice, but sacrifices some of the strength of the short splice. It does this by replacing two of the strands of each rope end with those from the other, cutting off some of the extra strands that result; the long splice allows the spliced rope to still fit through the same pulleys, necessary in some applications. Short splice – Also a splice used to join the ends of two ropes, but the short splice is more similar to the technique used in other splices and results in the spliced part being about twice as thick as the non spliced part, has greater strength than the long splice; the short splice retains more of the rope strength than any knots. Soft shackle – Dyneema soft shackles are strong and safe and are replacing stainless steel shackles. Splices are tapered to make the thicker splice blend into the rest of the line. There are two main types of tapering, the standard and the "West Coast Taper".
Standard tapers progressively remove a portion of each remaining strand—one-third at a time is typical, resulting in a taper of two additional tucks beyond the splice—thus making each successive tuck produce a narrower splice. This is only practical with laid-lines, i.e. those made up of numerous strands laid side by side. West Coast taper is effected by extra-tucks of entire strands, such that the second strand is interweaved one more time than the first and the third is interweaved an additional time after the second. A fid is a hand tool made from wood, plastic, or bone and is used in the process of working with rope. A variety of fid diameters are available depending on the size of rope being used. Styles of fid designs include: Swedish fid is conical instrument with a somewhat long taper. Tubular fid aid in splicing double-braided rope. Uni-fid needed to splice braid with a parallel core. A Marlinspike is a tool made of steel and part of a sailor's pocketknife, used to separate strands of rope from one another.
They flattened point. A pulling fid is used for smaller diameters of braided ropes. A Softfid is a great tool when dealing with braided ropes. Eye splice Stopping knot Whipping knot Western Union splice Nicopress Swaged Sleeve T-splice Talurit swaged sleeve Rat-tail splice David Steel, Explanation of the terms used in rigging, The Maritime History Virtual Archives A. Hyatt Verrill, Knots and Rope Work from Project Gutenberg Eye splice instruction with braided rope, ropeloft.co.uk Grog's Rope Splicing, Animated Knots by Grog Teufelberger Splicing Guides PremiumRopes Rope Splicing Instruction Videos
The eye splice is a method of creating a permanent loop in the end of a rope by means of rope splicing. The Flemish eye is a type of circular loop at the end of a thread. There are several techniques of creating the eye with its knot tied back to the rope or wire. There are various splicing techniques, relate to whether a rope is braided or plaited, whether it has a core and whether the core is made of high-performance fibers. Techniques include: Eye splice in three-strand rope Eye splice in eight-strand rope Eye splice in single braided rope Eye splice in double braided rope with polyester or nylon fiber core Eye splice in rope with braided cover and a laid core Eyes splice in rope with braided cover and parallel fibers in the core Eye splice in double braided rope with a high-performance fiber core For conventional stranded ropes, the ends of the rope are tucked back into the standing end to form the loop. Three tucks are the minimum for natural fibers, five tucks are necessary for synthetics.
Variations of this more traditional eye splice include: Round eyesplice used with round thimbles Lever's eyesplice used with teardrop thimbles Liverpool eyesplice used on wire ropeThe ends of the rope are first wrapped in tape or heated with a flame to prevent each end from fraying completely. The rope is unlayed for a distance equal to three times the diameter for each "tuck", e.g. for five tucks in half inch rope, undo about 7.5 inches. Wrap the rope at that point to prevent it unwinding further. Form the loop and plait the three ends back against the twist of the rope. Practice is required to keep each end to lie neatly. In stiff old rope or in new rope, wound, a marlinspike or fid can facilitate opening up the strands and threading each end. In some cases, the splice is tapered by trimming the working strands after each tuck; the splice can be whipped to protect and strengthen the splice. A rope thimble can be inserted in the eye to prevent chafing if the eye is to be permanently attached to a fixture.
An eight-strand rope consists of two right-twisting pairs. Make sure the left-twisting strands are fed below left-twisting strands, right-twisting strands below the right-twisting ones. Work systematically with different tape colours to keep from getting lost in the mess of strands. An eight-strand square plaited rope can anchor rode; this technique is used for Dyneema ropes. The principle of a Dyneema eye is a core-to-core splice, in which a length of at least 60 times the diameter of the rope is taken back into itself. DSM advises using 60 times the diameter for coated Dyneema, 100 times the diameter for uncoated Dyneema. For 6mm coated rope, this would mean 36 cm. Under tension the rope will pull into itself which produces a strong eye. One can pull out the eye. In ropes with a polyester core, both the core and the cover are neededfor strength. Splicing a rope with a laid core is more complicated than double braided polyester ropes. One needs more force to take the rope back into itself because there is less room between the core and the cover.
A rope with parallel fibers in the core has a tight inner cover to keep the fibers together. This splice is similar to the one for double braided polyester ropes, the main difference is that one cannot take the cover back in to the core because the fibers go through the core. Instructions are published in Splicing Modern Ropes For ropes with a core of high-performance fibers only the core determines the strength; the cover can be used optionally for example, to add UV protection. Dyneema is UV resistant and the cover is not needed. For these ropes, one could leave the cover unused. There are ropes with an extra double layer cover. Depending on the type of splice and rope, there is a variety of tools available such as hollow fids, pulling needles and traditional splicing fids. Make sure to have a marker, splicing tape, measuring tape and a knife or scissors at hand. A hammer and winch are used as well for tougher splices. A inch of good splice will hold 1 ton; the eye splice has several advantages.
The most notable is the permanence of the loop. An important advantage is the lack of stress it puts on the rope. Splices average 25-40% of rope strength decay, low compared to the strongest knots. Literature and reference sources attribute only a 5% strength decay for a properly tied splice. Technically, a tied splice retains 100% of the original strength of the rope but in practice this is the case. Destructive testing of rope in manufacturing facilities makes use of a professional and spliced eyes for connecting the rope to the testing apparatus; the bowline is a practical method of forming a loop in the end of a piece of rope. However, the bowline has an awkward tendency to shake undone; the bowline reduces the strength of the rope at the knot to ~45% of the original unknotted strength. List of knots Nicopress Swaged Sleeve Talurit swaged sleeve Wall and crown knot Grog. "Eye Splice". Animated Knots. Retrieved April 2013
Sail components include the features that define a sail's shape and function, plus its constituent parts from which it is manufactured. A sail may be classified in a variety of ways, including by its orientation to the vessel and its shape. Sails are constructed out of flexible material, shaped by various means, while in use, to offer an appropriate airfoil, according to the strength and apparent direction of the wind. A variety of features and fittings allow the sail to be attached to spars. Whereas conventional sails form an airfoil with one layer of fabric, wingsails comprise a structure that has material on both sides to form an airfoil—much like a wing placed vertically on the vessel—and are beyond the scope of this article. Sails may be classified as either triangular, which describes sails that either come to one point of suspension at the top or where the sail comes to a point at the forward end, or quadrilateral, which includes sails that are attached to a spar at the top and have three other sides, or as square.
They may be classified as symmetrical or asymmetrical. Asymmetrical sails perform better on points of sail closer to the wind than symmetrical sails and are designed for fore-and-aft rigs. Symmetrical sails perform best on points of sail. Triangular sails have names for each of three corners. Rigs with such sails include Bermuda, cutter and vessels with mixed sail plans that include jibs and other staysails. Most triangular sails are classified as fore and aft. Gaff, lug and some sprit sails have four sides and are set fore and aft so that one edge is leading into the wind, forming an asymmetric quadrilateral shape. Naming conventions are consistent with triangular sails, except for corners. A square rig is a type of sail and rigging arrangement in which the primary driving sails are carried on horizontal spars which are perpendicular, or square, to the keel of the vessel and to the masts—the sails themselves are not square but are symmetrically quadrilateral; these spars are called yards and their tips, beyond the last stay, are called the yardarms.
A ship so rigged is called a square-rigger. The shape of a sail is defined by its edges and corners in the plane of the sail, laid out on a flat surface; the edges may be curved, either to extend the sail's shape as an airfoil or to define its shape in use. In use, the sail becomes a curved shape, adding the dimension of draft; the top of all sails is called the head, the leading edge is called the luff, the trailing edge is the leech, the bottom edge is the foot. Head – The head is the upper edge of the sail, is attached at the throat and peak to a gaff, yard, or sprit. For a triangular sail the head refers to the topmost corner. Leech – The aft edge of a fore-and-aft sail is called the leech; the leech is either side edge of a symmetrical sail -- square. However, once a symmetrical sail has wind blowing along its surface, whether on a reach or close-hauled, the windward leech may be called a luff. Luff – The forward edge of a fore-and-aft sail is called the luff, may be attached along a mast or a stay.
When on a reach, the windward leech of a spinnaker is called the luff and, when on a reach or close-hauled, the windward leech of a square sail may be called the luff or the weather leech. Foot – The foot of a sail is its bottom edge. On a fore-and-aft mainsail, the foot is attached, at the tack and clew, to a boom. A fore-and-aft triangular mainsail achieves a better approximation of a wing form by extending the leech aft, beyond the line between the head and clew in an arc called the roach, rather than having a triangular shape; this added area would flutter in the wind and not contribute to the efficient airfoil shape of the sail without the presence of battens. Offshore cruising mainsails sometimes have a hollow leech to obviate the need for battens and their ensuing likelihood of chafing the sail. Roach is a term applied to square sail design—it is the arc of a circle above a straight line from clew to clew at the foot of a square sail, from which sail material is omitted; the roach allows the foot of the sail to clear stays coming up the mast, as the sails are rotated from side to side.
The names of corners of sails vary, depending on symmetry. Head – In a triangular sail, the corner where the luff and the leech connect is called the head. On a square sail, the top corners are head cringles. Peak – On a quadrilateral sail, the peak is the upper aft corner of the sail, at the top end of a gaff, a sprit or other spar. Throat – On a quadrilateral sail, the throat is the upper forward corner of the sail, at the bottom end of a gaff or other spar. Gaff-rigged sails, certain similar rigs, employ two halyards to raise the sails: the throat halyard raises the forward, throat end of the gaff, while the peak halyard raises the aft, peak end. Clew – The corner where the leech and foot connect is called the clew on a fore-and-aft sail. On a jib, the sheet is connected to the clew. Clews are the lower two corners of a square sail. Square sails have sheets attached to their clews like triangular sails, but the sheets are used to pull the sail down to the yard
Synthetic fibers are fibers made by humans with chemical synthesis, as opposed to natural fibers that humans get from living organisms with little or no chemical changes. They are the result of extensive research by scientists to improve on occurring animal fibers and plant fibers. In general, synthetic fibers are created by extruding fiber-forming materials through spinnerets into air and water, forming a thread; these fibers are called artificial fibers. Some fibers are manufactured from plant-derived cellulose and are thus semisynthetic, whereas others are synthetic, being made from crudes and intermediates including petroleum, coal and water. Joseph Swan invented the first artificial fiber in the early 1880s, his fiber was drawn from a cellulose liquid, formed by chemically modifying the fiber contained in tree bark. The synthetic fiber produced through this process was chemically similar in its potential applications to the carbon filament Swan had developed for his incandescent light bulb, but Swan soon realized the potential of the fiber to revolutionise textile manufacturing.
In 1885, he unveiled fabrics he had manufactured from his synthetic material at the International Inventions Exhibition in London. The next step was taken by Hilaire de Chardonnet, a French engineer and industrialist, who invented the first artificial silk, which he called "Chardonnet silk". In the late 1870s, Chardonnet was working with Louis Pasteur on a remedy to the epidemic, destroying French silkworms. Failure to clean up a spill in the darkroom resulted in Chardonnet's discovery of nitrocellulose as a potential replacement for real silk. Realizing the value of such a discovery, Chardonnet began to develop his new product, which he displayed at the Paris Exhibition of 1889. Chardonnet's material was flammable, was subsequently replaced with other, more stable materials; the first successful process was developed in 1894 by English chemist Charles Frederick Cross, his collaborators Edward John Bevan and Clayton Beadle. They named the fiber "viscose", because the reaction product of carbon disulfide and cellulose in basic conditions gave a viscous solution of xanthate.
The first commercial viscose rayon was produced by the UK company Courtaulds in 1905. The name "rayon" was adopted in 1924, with "viscose" being used for the viscous organic liquid used to make both rayon and cellophane. A similar product known as cellulose acetate was discovered in 1865. Rayon and acetate are both artificial fibers, but not synthetic, being made from wood. Nylon, the first synthetic fiber in the "fully synthetic" sense of that term, was developed by Wallace Carothers, an American researcher at the chemical firm DuPont in the 1930s, it soon made its debut in the United States as a replacement for silk, just in time for the introduction of rationing during World War II. Its novel use as a material for women's stockings overshadowed more practical uses, such as a replacement for the silk in parachutes and other military uses like ropes; the first polyester fiber was introduced by John Rex Whinfield and James Tennant Dickson, British chemists working at the Calico Printers' Association, in 1941.
They produced and patented the first polyester fiber which they named Terylene known as Dacron, equal to or surpassing nylon in toughness and resilience. ICI and DuPont went on to produce their own versions of the fiber; the world production of synthetic fibers was 55.2 million tonnes in 2014. Synthetic fibers are made from synthesized polymers of small molecules; the compounds that are used to make these fibers come from raw materials such as petroleum based chemicals or petrochemicals. These materials are polymerized into a linear chemical that bond two adjacent carbon atoms. Differing chemical compounds will be used to produce different types of synthetic fibers. Synthetic fibers account for about half of all fiber usage, with applications in every field of fiber and textile technology. Although many classes of fiber based on synthetic polymers have been evaluated as valuable commercial products, four of them - nylon, polyester and polyolefin - dominate the market; these four account for 98 percent by volume of synthetic fiber production, with polyester alone accounting for around 60 per cent.
There are several methods of manufacturing synthetic fibers but the most common is the Melt-Spinning Process. It involves heating the fiber until it begins to melt you must draw out the melt with tweezers as as possible; the next step would be to draw the molecules by aligning them in a parallel arrangement. This allows them to crystallize and orient. Lastly, is Heat-Setting; this utilizes heat to permeate the shape/dimensions of the fabrics made from heat-sensitive fibers. Synthetic fibers are more durable than most natural fibers and will pick-up different dyes. In addition, many synthetic fibers offer consumer-friendly functions such as stretching and stain resistance. Sunlight and oils from human skin cause all fibers to break down and wear away. Natural fibers tend to be much more sensitive than synthetic blends; this is because natural products are biodegradable. Natural fibers are susceptible to larval insect infestation. Compared to natural fibers, many synthetic fibers are more water stain resistant.
Some are specially enhanced to withstand damage from water or stains. Some fabrics are designed to stretch in specific ways, which makes them more comfortable to wear. Cotton production is resource intensive: it takes sign
Twaron is a para-aramid. It is a heat-resistant and strong synthetic fibre developed in the early 1970s by the Dutch company AKZO, division ENKA Akzo Industrial Fibers; the research name of the para-aramid fibre was Fiber X, but it was soon called Arenka. Although the Dutch para-aramid fiber was developed only a little than DuPont's Kevlar, introduction of Twaron as a commercial product came much than Kevlar due to financial problems at the AKZO company in the 1970s; this is a chronology of the development of Twaron: In 1960s a research program starts for "Fiber X." In 1972 the ENKA Research laboratory develops. In 1973 Akzo decides to use sulfuric acid as a solvent for spinning. In 1974 New process route was found at Akzo Research laboratory, using N-methylpyrrolidone with a co-solvent with an ionic component (Calcium Chloride to occupy the hydrogen bonds of the amide groups in order to dissolve the aromatic polymer. In 1976 a pilot plant is built. In 1977 first production starts. In 1984 the product is renamed Twaron.
In 1986 commercial production is started at nine plants. In 1987 Twaron is introduced as a commercial product. In 1989 the aramid business of Akzo becomes an independent Business Unit called Twaron BV. Since 2000 Twaron BV is owned by the Teijin Group, now called Teijin Twaron BV and based in Arnhem, Netherlands; the main production facilities for Twaron are in Delfzijl. In 2007 Teijin Twaron expands for the fourth time in six years and changes its name into Teijin Aramid. Twaron is the simplest form of the AABB para polyaramide. PpPTA is a product of p-phenylene terephthaloyl dichloride. To dissolve the aromatic polymer Twaron used a co-solvent of N-methyl pyrrolidone and an ionic component to occupy the hydrogen bonds of the amide groups; the invention of this specific process was done in 1974 at AKZO Research Laboratory in Arnhem by a team consisting of Leo Vollbracht, Teun Veerman and Wim Engelhard. The patent of the newly discovered process route led to a patent war between AKZO and DuPont as Dupont used the carcinogenic HMPT.
Despite heavy research DuPont now applies the AKZO patent for their Kevlar process and use the less hazardous NMP. After the production of the Twaron polymer in Delfzijl, the polymer is brought to Emmen, where fibres are produced by spinning the dissolved polymer into a solid fibre from a liquid chemical blend. Polymer solvent for spinning PPTA is 100% anhydrous sulfuric acid; the polymer is dissolved by mixing frozen sulfuric acid in powder form with the polymer in powder form and heating the mixture. This process, which differs from the more difficult DuPont process, was invented by Henri Lammers and patented by AKZO. Twaron is a para-aramid and is used in automotive, sport, aerospace and industry applications, e.g. "bullet-proof" body armor, as an asbestos substitute. Protective gear flame-resistant clothing, protective clothing and helmets, cut-fast or heat-hardy gloves, sporting goods, ballistic vests Composites composite materials, technical paper, asbestos replacement, hot air filtration, speaker woofers, boat hull material, fiber reinforced concrete, drumheads Automotive brake pads, turbo hoses, V-belts and Timing belts, tires that incorporate Sulfron, mechanical rubber goods reinforcement Linear tension optical fiber cables, wire ropes, electrical cables, umbilical cables, electrical mechanical cable, reinforced thermoplastic pipes Aramid Fibers Kégresse track Nylon Kevlar Personal protective equipment Technora Vectran JWS Hearle.
High-performance fibres. Woodhead Publishing Ltd. Abington, UK - The Textile Institute. ISBN 978-1-85573-539-2. Doetze J. Sikkema. "Manmade fibers one hundred years: Polymers and polymer design". J Appl Polym Sci: 484–488. L. Vollbracht and T. J. Veerman, US Patent 4308374 Official Twaron website General Aramid information