The Basics of Aramid Fiber, Polymer Reinforcing Fiber

The Basics of Aramid Fiber, Polymer Reinforcing Fiber Aramid fiber is the generic name of a group of synthetic fibers. The fibers offer a set of properties which make them particularly useful in armor, clothing and a wide range of other applications. The most commonly known commercial brand is Kevlarâ„ ¢, but there others such as Twaronâ„ ¢ and Nomexâ„ ¢ in the same broad family. History Aramids have evolved out of research which stretches back to nylon and polyester. The family is known as aromatic polyamides. Nomex was developed in the early 1960’s and its properties led to wide use in protective clothing, insulation and as a replacement for asbestos. Further research with this meta-aramid led to the fiber we now know as Kevlar. Kevlar and Twaron are para-aramids. Kevlar was developed and trademarked by DuPont and became commercially available in 1973. 2011 worldwide production of Aramids was well over 60,000 tons, and demand is growing steadily as production scales up, costs fall and applications broaden. Properties The chemical structure of the chain molecules is such that the bonds are aligned (for the most part) along the fiber axis, giving them outstanding strength, flexibility and abrasion tolerance. With outstanding resistance to heat and low flammability, they are unusual in that they do not melt – they merely start to degrade (at about 500 degrees Centigrade). They also have very low electrical conductivity making them ideal electrical insulators. With high resistance to organic solvents, the all-around ‘inert’ aspects of these materials offer outstanding versatility for a huge range of applications. The only blot on their horizons is that they are sensitive to UV, acids, and salts. They build static electricity too unless they are specially treated. The outstanding properties which these fibers enjoy provide advantages which make them ideal for a wide range of applications. However, with any composite material, it is important to take care in  handling  and processing. Using gloves, masks, etc. is advisable. Applications Kevlar’s original use was for car tire reinforcement, where the technology still dominates, but in transport, the fibers are used as a replacement for asbestos – for example in brake linings. Probably the most widely known application is in body armor, but other protective uses include fireproof suits for firefighters, helmets, and gloves. Their high strength/weight ratio makes them attractive for use as reinforcing (for example in composite materials particularly where flexing tolerance is important, such as aircraft wings). In construction, we have fiber-reinforced concrete and thermoplastic pipes. Corrosion is a major problem for expensive undersea pipelines in the oil industry, and thermoplastic pipe technology was developed to prolong pipeline life and reduce maintenance costs. Their low stretch properties (typically 3.5% at break), high strength and abrasion resistance make aramid fibers ideal for ropes and cables, and they are even used for mooring ships. In the sporting arena, bowstrings, tennis racquet strings, hockey sticks, skis and running shoes are some of the application areas for these outstanding fibers, with sailors enjoying the benefits of aramid-reinforced hulls, aramid lines and Kevlar wear-patches on their elbows, knees, and rears! Even in the music world aramid fibers are making themselves heard as instrument reeds and drumheads, with the sound being relayed through aramid-fiber loudspeaker cones. The Future New applications are being announced regularly, for example, a high-performance protective coating for harsh environments which embeds Kevlar fibers in an ester. This is ideal for coating new steel pipelines – for example in utilities where water pipes may bury underground and budgets do not permit the more expensive thermoplastic alternatives. With improved epoxies and other resins being introduced on a regular basis and given the continuous scaling up in worldwide production of aramids in many forms (fiber, pulp, powder, chopped fiber and woven mat) the increased use of the material is guaranteed both in its raw form and in composites.