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IUPAC name poly(p-phenylene-2,6-benzobisoxazole) [1] | |
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CompTox Dashboard (EPA) | |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). |
Zylon (IUPAC name: poly(p-phenylene-2,6-benzobisoxazole)) is a trademarked name for a range of thermoset liquid-crystalline polyoxazole. This synthetic polymer material was invented and developed by SRI International in the 1980s and manufactured by Toyobo. [2] In generic usage, the fiber is referred to as PBO. [3]
Zylon has 5.8 GPa of tensile strength, [4] which is 1.6 times that of Kevlar. Additionally, Zylon has a high Young's modulus of 270 GPa, meaning that it is stiffer than steel. Like Kevlar, Zylon is used in a number of applications that require very high strength with excellent thermal stability. The material has been used in body armour, in tennis racquets, table tennis paddles, and in snowboards, in various medical applications, and in some of the Martian rovers.
Zylon gained wide use in U.S. police officers body armor protection in 1998 with its introduction by Second Chance Body Armor, Inc. in its "Ultima" and "Ultimax" protective vests. Protective vests constructed with Zylon were questioned in late 2003 when Oceanside, CA Police Officer Tony Zeppetella's and Forest Hills, PA Police Officer Ed Limbacher's vests both failed, leaving Zeppetella mortally wounded and Limbacher seriously injured. Some studies subsequently reported that the Zylon vests might degrade over time [5] and leave their wearers with less protection than expected. Second Chance eventually recalled all of its Zylon vests, which led to its bankruptcy. In early 2005, Armor Holdings, Inc. recalled its Zylon-based products, and decreased the rated lifespan warranty of new vests from 60 months to 30 months. [6] In August 2005, AHI decided to discontinue manufacturing all of its Zylon-containing vests. This was largely based on the actions of the U.S. government's National Institute of Justice, which decertified Zylon for use in its approved models of ballistic vests for law enforcement. [7]
The United States Justice Department launched numerous investigations into possible violations of the False Claims Act regarding the defective vests. Throughout the course of litigation, settlements totaling more than $136 million were reached with 18 entities involved in the production and sale of Zylon vests. The investigations concluded after nearly two decades when the final settlement was obtained with material supplier Honeywell International in late 2022. [8]
A competition was held in the Wirefly X Prize Cup in Las Cruces, New Mexico, US, on October 20–21, 2006. A team from the University of British Columbia entered into the Tether Challenge, using a construction made from Zylon fibers. The house tether used by Spaceward, that the other teams would have to beat in strength by 50% in the 2007 Spaceward games, [9] was made of Zylon.
Zylon is used by NASA in long-duration, high-altitude data collection. Braided Zylon strands maintain the structure of polyethylene superpressure balloons. Zylon is the material of choice due to its low weight, high tensile strength, and thermal properties. [10]
Since 2001 Zylon tethers are used in Formula One to attach the wheels to the chassis, thus preventing the wheel from ejecting into a crowded area in the event of an accident which causes the wheel to become airborne. Starting in the 2007 season, the driver's cockpit must now be clad in special anti-penetration panels made of Zylon. [11] In 2011, a Zylon strip was introduced to reinforce the top of the racing helmet visor [12] and provide an overlap between the visor and helmet for additional protection after Felipe Massa's 2009 injury. The Indy Racing League began using Zylon in 2008. [13]
On modern racing yachts, Zylon is used for parts of the standing rigging. It is used as shrouds and stays. The PBO (polybenzoxazole) fiber is degraded by UV light, seawater, and chafing (the problem that caused Zylon to be removed from usage in protective vests for police usage, as shown above), and is therefore protected by a synthetic melted-on jacket. It is claimed to be 65% lighter than traditional rigging at 110–130% of the price of rod rigging. [14] Based on laboratory tests, superior durability is also claimed.
SpaceX uses Zylon for the suspension lines on their Mk3 parachutes. Four Mk3 parachutes serve as the main parachutes on each of SpaceX's human-rated Crew Dragon spacecraft. [15]
Zylon has been incorporated as the base fiber for some conductive textiles, where the Zylon fiber is plated with nickel, copper, silver, or gold. The conductive fiber is used for electronic textiles, EMI shielding in woven or knit sheets, or as a braid over wires, and for signal transmission or current conduction. This conductive fiber combines the advantages of Zylon (strength, resistance to high temperatures, durability, lightweight, etc.) with the electrical properties of various metals. The conductive yarns can be sewn, braided, knit, or simply insulated like a bare wire. [16]
PBO is the strongest and stiffest of commercially available fibers used to repair and strengthen concrete and masonry structures in externally bonded composite systems. [17] In this system, the fibers are produced in the form of a fabric mesh, and a cementitious mortar matrix bonds this to an existing structure.
Yamaha uses Zylon to make the speaker cones for its top-of-the-line NS-5000 speaker. [18]
Spinergy, Inc. produces wheels for bicycles and wheelchairs with PBO spokes. They claim their PBO fiber spokes act as a vibration and shock damper, while being lighter and stronger than steel spokes. [19]
Kevlar (para-aramid) is a strong, heat-resistant synthetic fiber, related to other aramids such as Nomex and Technora. Developed by Stephanie Kwolek at DuPont in 1965, the high-strength material was first used commercially in the early 1970s as a replacement for steel in racing tires. It is typically spun into ropes or fabric sheets that can be used as such, or as an ingredient in composite material components.
A helmet is a form of protective gear worn to protect the head. More specifically, a helmet complements the skull in protecting the human brain. Ceremonial or symbolic helmets without protective function are sometimes worn. Soldiers wear combat helmets, often made from Kevlar or other lightweight synthetic fibers.
A bulletproof vest, also known as a ballistic vest or bullet-resistant vest, is a type of body armour designed to absorb impact and prevent the penetration of firearm projectiles and explosion fragments to the torso. The vest can be either soft—as worn by police officers, security personnel, prison guards, and occasionally private citizens to protect against stabbing attacks or light projectiles—or hard, incorporating metallic or para-aramid components. Soldiers and police tactical units typically wear hard armour, either alone or combined with soft armour, to protect against rifle ammunition or fragmentation. Additional protection includes trauma plates for blunt force and ceramic inserts for high-caliber rounds. Bulletproof vests have evolved over centuries, from early designs like those made for knights and military leaders to modern-day versions. Early ballistic protection used materials like cotton and silk, while contemporary vests employ advanced fibers and ceramic plates. Ongoing research focuses on improving materials and effectiveness against emerging threats.
Synthetic fibers or synthetic fibres are fibers made by humans through chemical synthesis, as opposed to natural fibers that are directly derived from living organisms, such as plants or fur from animals. They are the result of extensive research by scientists to replicate naturally occurring animal and plant fibers. In general, synthetic fibers are created by extruding fiber-forming materials through spinnerets, forming a fiber. These are called synthetic or artificial fibers. The word polymer comes from a Greek prefix "poly" which means "many" and suffix "mer" which means "single units"..
Aramid fibers, short for aromatic polyamide, are a class of heat-resistant and strong synthetic fibers. They are used in aerospace and military applications, for ballistic-rated body armor fabric and ballistic composites, in marine cordage, marine hull reinforcement, as an asbestos substitute, and in various lightweight consumer items ranging from phone cases to tennis rackets.
A shackle, also 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 also applies to handcuffs and other similarly 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.
Webbing is a strong fabric woven as a flat strip or tube of varying width and fibres, often used in place of rope. It is a versatile component used in climbing, slacklining, furniture manufacturing, automobile safety, auto racing, towing, parachuting, military apparel, load securing, and many other fields.
Body armor, personal armor, armored suit (armoured) or coat of armor, among others, is armor for a person's body: protective clothing or close-fitting hands-free shields designed to absorb or deflect physical attacks. Historically used to protect military personnel, today it is also used by various types of police, private security guards, or bodyguards, and occasionally ordinary citizens. Today there are two main types: regular non-plated body armor for moderate to substantial protection, and hard-plate reinforced body armor for maximum protection, such as used by combatants.
Bulletproofing is the process of making an object capable of stopping a bullet or similar high velocity projectiles. The term bullet resistance is often preferred because few, if any, practical materials provide complete protection against all types of bullets, or multiple hits in the same location, or simply sufficient kinetic (movement) energy to overcome it.
Gold Flex is a non-woven fabric manufactured by Honeywell from Kevlar, and is often used in ballistic vests and body armor. Gold Flex is lighter than woven Kevlar, Twaron and other Ballistic material. Gold Flex is a laminated material consisting of cross-laid, non-woven fibers in a resin matrix. The fibers are laid straight and not in a woven fabric configuration. When an object strikes this material, a "web" of its clusters absorb the impact and minimizes penetration.
Ultra-high-molecular-weight polyethylene is a subset of the thermoplastic polyethylene. Also known as high-modulus polyethylene (HMPE), it has extremely long chains, with a molecular mass usually between 3.5 and 7.5 million amu. The longer chain serves to transfer load more effectively to the polymer backbone by strengthening intermolecular interactions. This results in a very tough material, with the highest impact strength of any thermoplastic presently made.
Ballistic nylon is a thick, tough, nylon fabric with several uses. Ballistic nylon was developed by the DuPont corporation as a material for flak jackets for World War II airmen. It was called ballistic because, together with other components, it was intended to protect its wearers from flying debris and fragmentation from bullet and artillery-shell impacts.
Armor Holdings, Inc. was an American manufacturer of military, law enforcement, and personnel safety equipment. It was acquired by BAE Systems on July 31, 2007 and renamed BAE Systems Mobility & Protection Systems. The divisions have been reorganised within BAE Systems Land and Armaments.
A fiber-optic cable, also known as an optical-fiber cable, is an assembly similar to an electrical cable but containing one or more optical fibers that are used to carry light. The optical fiber elements are typically individually coated with plastic layers and contained in a protective tube suitable for the environment where the cable is used. Different types of cable are used for fiber-optic communication in different applications, for example long-distance telecommunication or providing a high-speed data connection between different parts of a building.
Elevator:2010 was an inducement prize contest with the purpose of developing space elevator and space elevator-related technologies. Elevator:2010 organized annual competitions for climbers, ribbons and power-beaming systems, and was operated by a partnership between Spaceward Foundation and the NASA Centennial Challenges.
A conductive textile is a fabric which can conduct electricity. Conductive textiles known as lamé are made with guipé thread or yarn that is conductive because it is composed of metallic fibers wrapped around a non-metallic core or has a metallic coating. A different way of achieving conductivity is to weave metallic strands into the textile.
The use of personal protective equipment (PPE) is inherent in the theory of universal precaution, which requires specialized clothing or equipment for the protection of individuals from hazard. The term is defined by the Occupational Safety and Health Administration (OSHA), which is responsible for PPE regulation, as the "equipment that protects employees from serious injury or illness resulting from contact with chemical, radiological, physical, electrical, mechanical, or other hazards." While there are common forms of PPEs such as gloves, eye shields, and respirators, the standard set in the OSHA definition indicates a wide coverage. This means that PPE involves a sizable range of equipment. There are several ways to classify them such as how gears could be physiological or environmental. The following list, however, sorts personal protective equipment according to function and body area.
Kevlar KM2 is a synthetic para-aramid fibre produced by DuPont. The fiber is an evolution of the original Kevlar fibre. The following quotes summarise Kevlar KM2's properties.
Space tethers are long cables which can be used for propulsion, momentum exchange, stabilization and attitude control, or maintaining the relative positions of the components of a large dispersed satellite/spacecraft sensor system. Depending on the mission objectives and altitude, spaceflight using this form of spacecraft propulsion is theorized to be significantly less expensive than spaceflight using rocket engines.