Ultra-high-molecular-weight polyethylene

From Wikipedia, the free encyclopedia

https://en.wikipedia.org/wiki/Ultra-high-molecular-weight_polyethylene 

Ultra-high-molecular-weight polyethylene (UHMWPE, UHMW) 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.

UHMWPE is odorless, tasteless, and nontoxic. It embodies all the characteristics of high-density polyethylene (HDPE) with the added traits of being resistant to concentrated acids and alkalis, as well as numerous organic solvents. It is highly resistant to corrosive chemicals except oxidizing acids; has extremely low moisture absorption and a very low coefficient of friction; is self-lubricating (see boundary lubrication); and is highly resistant to abrasion, in some forms being 15 times more resistant to abrasion than carbon steel. Its coefficient of friction is significantly lower than that of nylon and acetal and is comparable to that of polytetrafluoroethylene (PTFE, Teflon), but UHMWPE has better abrasion resistance than PTFE.

Development

Polymerization of UHMWPE was commercialized in the 1950s by Ruhrchemie AG, which has changed names over the years. Today UHMWPE powder materials, which may be directly molded into a product's final shape, are produced by, Ticona, Braskem, Teijin (Endumax), Celanese, and Mitsui. Processed UHMWPE is available commercially either as fibers or in consolidated form, such as sheets or rods. Because of its resistance to wear and impact, UHMWPE continues to find increasing industrial applications, including the automotive and bottling sectors. Since the 1960s, UHMWPE has also been the material of choice for total joint arthroplasty in orthopedic and spine implants.

UHMWPE fibers branded as Dyneema, commercialized in the late 1970s by the Dutch chemical company DSM, and as Spectra, commercialized by Honeywell (then AlliedSignal), are widely used in ballistic protection, defense applications, and increasingly in medical devices, sailing, hiking equipment, climbing, and many other industries.

Structure and properties

Structure of UHMWPE, with n greater than 100,000

UHMWPE is a type of polyolefin. It is made up of extremely long chains of polyethylene, which all align in the same direction. It derives its strength largely from the length of each individual molecule (chain). Van der Waals forces between the molecules are relatively weak for each atom of overlap between the molecules, but because the molecules are very long, large overlaps can exist, adding up to the ability to carry larger shear forces from molecule to molecule. Each chain is attracted to the others with so many van der Waals forces that the whole of the inter-molecular strength is high. In this way, large tensile loads are not limited as much by the comparative weakness of each localized van der Waals force.

When formed into fibers, the polymer chains can attain a parallel orientation greater than 95% and a level of crystallinity from 39% to 75%. In contrast, Kevlar derives its strength from strong bonding between relatively short molecules.

The weak bonding between olefin molecules allows local thermal excitations to disrupt the crystalline order of a given chain piece-by-piece, giving it much poorer heat resistance than other high-strength fibers. Its melting point is around 130 to 136 °C (266 to 277 °F), and, according to DSM, it is not advisable to use UHMWPE fibres at temperatures exceeding 80 to 100 °C (176 to 212 °F) for long periods of time. It becomes brittle at temperatures below −150 °C (−240 °F).

The simple structure of the molecule also gives rise to surface and chemical properties that are rare in high-performance polymers. For example, the polar groups in most polymers easily bond to water. Because olefins have no such groups, UHMWPE does not absorb water readily, nor wet easily, which makes bonding it to other polymers difficult. For the same reasons, skin does not interact with it strongly, making the UHMWPE fiber surface feel slippery. In a similar manner, aromatic polymers are often susceptible to aromatic solvents due to aromatic stacking interactions, an effect aliphatic polymers like UHMWPE are immune to. Since UHMWPE does not contain chemical groups (such as esters, amides or hydroxylic groups) that are susceptible to attack from aggressive agents, it is very resistant to water, moisture, most chemicals, UV radiation, and micro-organisms.

Under tensile load, UHMWPE will deform continually as long as the stress is present—an effect called creep.

When UHMWPE is annealed, the material is heated to between 135 °C (275 °F) and 138 °C (280 °F) in an oven or a liquid bath of silicone oil or glycerine. The material is then cooled down at a rate of 5 °C/h (2.5 °F/ks) to 65 °C (149 °F) or less. Finally, the material is wrapped in an insulating blanket for 24 hours to bring to room temperature.

Production

Ultra-high-molecular-weight polyethylene (UHMWPE) is synthesized from its monomer ethylene, which is bonded together to form the base polyethylene product. These molecules are several orders of magnitude longer than those of familiar high-density polyethylene (HDPE) due to a synthesis process based on metallocene catalysts, resulting in UHMWPE molecules typically having 100,000 to 250,000 monomer units per molecule each compared to HDPE's 700 to 1,800 monomers.

UHMWPE is processed variously by compression moulding, ram extrusion, gel spinning, and sintering. Several European companies began compression molding UHMWPE in the early 1960s. Gel-spinning arrived much later and was intended for different applications.

In gel spinning a precisely heated gel of UHMWPE is extruded through a spinneret. The extrudate is drawn through the air and then cooled in a water bath. The end-result is a fiber with a high degree of molecular orientation, and therefore exceptional tensile strength. Gel spinning depends on isolating individual chain molecules in the solvent so that intermolecular entanglements are minimal. Entanglements make chain orientation more difficult, and lower the strength of the final product.

Applications

Fiber

LIROS Dyneema hollow

Dyneema and Spectra are brands of lightweight high-strength oriented-strand gels spun through a spinneret. They have yield strengths as high as 2.4 GPa (350,000 psi) and density as low as 0.97 g/cm (0.087 oz/in) (for Dyneema SK75). High-strength steels have comparable yield strengths, and low-carbon steels have yield strengths much lower (around 0.5 GPa (73,000 psi)). Since steel has a specific gravity of roughly 7.8, these materials have a strength-to-weight ratios eight times that of high-strength steels. Strength-to-weight ratios for UHMWPE are about 40% higher than for aramid. The high qualities of UHMWPE filament were discovered by Albert Pennings in 1968, but commercially viable products were made available by DSM in 1990 and Southern Ropes soon after.

Derivatives of UHMWPE yarn are used in composite plates in armor, in particular, personal armor and on occasion as vehicle armor. Civil applications containing UHMWPE fibers are cut-resistant gloves, tear-resistant hosiery, bow strings, climbing equipment, automotive winching, fishing line, spear lines for spearguns, high-performance sails, suspension lines on sport parachutes and paragliders, rigging in yachting, kites, and kite lines for kites sports.

For personal armor, the fibers are, in general, aligned and bonded into sheets, which are then layered at various angles to give the resulting composite material strength in all directions. Recently developed additions to the US Military's Interceptor body armor, designed to offer arm and leg protection, are said to utilize a form of UHMWPE fabric. A multitude of UHMWPE woven fabrics are available in the market and are used as shoe liners, pantyhose, fencing clothing, stab resistant vests and as composite liners for vehicles.

The use of UHMWPE rope for automotive winching offers several advantages over the more common steel wire. The key reason for changing to UHMWPE rope is improved safety. The lower mass of UHMWPE rope, coupled with significantly lower elongation at breaking, carries far less energy than steel or nylon, which leads to almost no snap-back. UHMWPE rope does not develop kinks that can cause weak spots, and any frayed areas that may develop along the surface of the rope cannot pierce the skin like broken wire strands can. UHMWPE rope is less dense than water, making water recoveries easier as the recovery cable is easier to locate than wire. The bright colours available also aid with visibility should the rope become submerged or dirty. Another advantage in automotive applications is the reduced weight of UHMWPE rope over steel cables. A typical 11 mm (0.43 in) UHMWPE rope of 30 m (98 ft) can weigh around 2 kg (4.4 lb), the equivalent steel wire rope would weigh around 13 kg (29 lb). One notable drawback of UHMWPE rope is its susceptibility to UV damage, so many users will fit winch covers in order to protect the cable when not in use. It is also vulnerable to heat damage from contact with hot components.

Spun UHMWPE fibers excel as fishing line, as they have less stretch, are more abrasion-resistant, and are thinner than the equivalent monofilament line.

In climbing, cord and webbing made of combinations of UHMWPE and nylon yarn have gained popularity for their low weight and bulk. They exhibit very low elasticity compared to their nylon counterparts, which translates to low toughness. The fiber's very high lubricity causes poor knot-holding ability, and it is mostly used in pre-sewn 'slings' (loops of webbing)—relying on knots to join sections of UHMWPE is generally not recommended, and if necessary it is recommended to use the triple fisherman's knot rather than the traditional double fisherman's knot.

Ships' hawsers and cables made from the fiber (0.97 specific gravity) float on sea water. "Spectra wires" as they are called in the towing boat community are commonly used for face wires as a lighter alternative to steel wires.

It is used in skis and snowboards, often in combination with carbon fiber, reinforcing the fiberglass composite material, adding stiffness and improving its flex characteristics. The UHMWPE is often used as the base layer, which contacts the snow, and includes abrasives to absorb and retain wax.

It is also used in lifting applications, for manufacturing low weight, and heavy duty lifting slings. Due to its extreme abrasion resistance it is also used as an excellent corner protection for synthetic lifting slings.

High-performance lines (such as backstays) for sailing and parasailing are made of UHMWPE, due to their low stretch, high strength, and low weight. Similarly, UHMWPE is often used for winch-launching gliders from the ground, as, in comparison with steel cable, its superior abrasion resistance results in less wear when running along the ground and into the winch, increasing the time between failures. The lower weight on the mile-long cables used also results in higher winch launches.

UHMWPE was used for the 30 km (19 mi) long, 0.6 mm (0.024 in) thick space tether in the ESA/Russian Young Engineers' Satellite 2 of September, 2007.

Dyneema Composite Fabric (DCF) is a laminated material consisting of a grid of Dyneema threads sandwiched between two thin transparent polyester membranes. This material is very strong for its weight, and was originally developed for use in racing yacht sails under the name 'Cuben Fiber'. More recently it has found new applications, most notably in the manufacture of lightweight and ultralight camping and backpacking equipment such as tents and backpacks.

In archery, UHMWPE is widely used as a material for bowstrings because of its low creep and stretch compared to, for example, Dacron (PET). Besides pure UHMWPE fibers, most manufacturers use blends to further reduce the creep and stretch of the material. In these blends, the UHMWPE fibers are blended with, for example, Vectran.

In skydiving, UHMWPE is one of the most common materials used for suspension lines, largely supplanting the earlier-used Dacron, being lighter and less bulky. UHMWPE has excellent strength and wear-resistance, but is not dimensionally stable (i.e. shrinks) when exposed to heat, which leads to gradual and uneven shrinkage of different lines as they are subject to differing amounts of friction during canopy deployment, necessitating periodic line replacement. It is also almost completely inelastic, which can exacerbate the opening shock. For that reason, Dacron lines continue to be used in student and some tandem systems, where the added bulk is less of a concern than the potential for an injurious opening. In turn, in high performance parachutes used for swooping, UHMWPE is replaced with Vectran and HMA (high-modulus aramid), which are even thinner and dimensionally stable, but exhibit greater wear and require much more frequent maintenance to prevent catastrophic failure. UHMWPE are also used for reserve parachute closing loops when used with automatic activation devices, where their extremely low coefficient of friction is critical for proper operation in the event of cutter activation.

Medical

UHMWPE has a clinical history as a biomaterial for use in hip, knee, and (since the 1980s), for spine implants. An online repository of information and review articles related to medical grade UHMWPE, known as the UHMWPE Lexicon, was started online in 2000.

Joint replacement components have historically been made from "GUR" resins. These powder materials are produced by Ticona, typically converted into semi-forms by companies such as Quadrant and Orthoplastics, and then machined into implant components and sterilized by device manufacturers.

UHMWPE was first used clinically in 1962 by Sir John Charnley and emerged as the dominant bearing material for total hip and knee replacements in the 1970s. Throughout its history, there were unsuccessful attempts to modify UHMWPE to improve its clinical performance until the development of highly cross-linked UHMWPE in the late 1990s.

One unsuccessful attempt to modify UHMWPE was by blending the powder with carbon fibers. This reinforced UHMWPE was released clinically as "Poly Two" by Zimmer in the 1970s. The carbon fibers had poor compatibility with the UHMWPE matrix and its clinical performance was inferior to virgin UHMWPE.

A second attempt to modify UHMWPE was by high-pressure recrystallization. This recrystallized UHMWPE was released clinically as "Hylamer" by DePuy in the late 1980s. When gamma irradiated in air, this material exhibited susceptibility to oxidation, resulting in inferior clinical performance relative to virgin UHMWPE. Today, the poor clinical history of Hylamer is largely attributed to its sterilization method, and there has been a resurgence of interest in studying this material (at least among certain research circles). Hylamer fell out of favor in the United States in the late 1990s with the development of highly cross-linked UHMWPE materials, however negative clinical reports from Europe about Hylamer continue to surface in the literature.

Highly cross-linked UHMWPE materials were clinically introduced in 1998 and have rapidly become the standard of care for total hip replacements, at least in the United States. These new materials are cross-linked with gamma or electron beam radiation (50–105 kGy) and then thermally processed to improve their oxidation resistance. Five-year clinical data, from several centers, are now available demonstrating their superiority relative to conventional UHMWPE for total hip replacement (see arthroplasty). Clinical studies are still underway to investigate the performance of highly cross-linked UHMWPE for knee replacement.

In 2007, manufacturers started incorporating anti-oxidants into UHMWPE for hip and knee arthroplasty bearing surfaces. Vitamin E (a-tocopherol) is the most common anti-oxidant used in radiation-cross-linked UHMWPE for medical applications. The anti-oxidant helps quench free radicals that are introduced during the irradiation process, imparting improved oxidation resistance to the UHMWPE without the need for thermal treatment. Several companies have been selling antioxidant-stabilized joint replacement technologies since 2007, using both synthetic vitamin E as well as hindered phenol-based antioxidants.

Another important medical advancement for UHMWPE in the past decade has been the increase in use of fibers for sutures. Medical-grade fibers for surgical applications are produced by DSM under the "Dyneema Purity" trade name.

Manufacturing

UHMWPE is used in the manufacture of PVC (vinyl) windows and doors, as it can endure the heat required to soften the PVC-based materials and is used as a form/chamber filler for the various PVC shape profiles in order for those materials to be 'bent' or shaped around a template.

UHMWPE is also used in the manufacture of hydraulic seals and bearings. It is best suited for medium mechanical duties in water, oil hydraulics, pneumatics, and unlubricated applications. It has a good abrasion resistance but is better suited to soft mating surfaces.

Wire/cable

Fluoropolymer / HMWPE insulation cathodic protection cable is typically made with dual insulation. It features a primary layer of a fluoropolymer such as ECTFE which is chemically resistant to chlorine, sulphuric acid and hydrochloric acid. Following the primary layer is an HMWPE insulation layer, which provides pliable strength and allows considerable abuse during installation. The HMWPE jacketing provides mechanical protection as well.

Marine infrastructure

UHMWPE is used in marine structures for the mooring of ships and floating structures in general. The UHMWPE forms the contact surface between the floating structure and the fixed one. Timber was and is used for this application also. UHMWPE is chosen as facing of fender systems for berthing structures because of the following characteristics:

• Wear resistance: best among plastics, better than steel
• Impact resistance: best among plastics, similar to steel
• Low friction (wet and dry conditions): self-lubricating material

Five-year plans of China

From Wikipedia, the free encyclopedia

https://en.wikipedia.org/wiki/Five-year_plans_of_China 

The Five-Year Plans (simplified Chinese: 五年计划; traditional Chinese: 五年計劃; pinyin: Wǔnián Jìhuà) are a series of social and economic development initiatives issued by the Chinese Communist Party (CCP) since 1953 in the People's Republic of China. Since 1949, the CCP has shaped the Chinese economy through the plenums of its Central Committee and national party congresses.

Planning is a key characteristic of the nominally socialist economies, and one plan established for the entire country normally contains detailed economic development guidelines for all its regions. In order to more accurately reflect China's transition from a Soviet-style command economy to a socialist market economy (socialism with Chinese characteristics), the plans since the 11th Five-Year Plan for 2006 to 2010 have been referred to in Chinese as "guidelines" (simplified Chinese: 规划; traditional Chinese: 規劃; pinyin: guīhuà) instead of as "plans" (simplified Chinese: 计划; traditional Chinese: 計劃; pinyin: jìhuà).

Role

Medium and long-term planning are central to coordinating state activity across many policy areas in China and China's Five-Year Plans are one of the most prominent examples of this approach. Through the Five-Year Plans, the CCP and the government establish their policy priorities. Five-Year Plans continue to be a central means of organizing policy in China, especially in the areas of environmental protection, education, and industrial policy.

The initial formulation of a Five-Year Plan beings with fairly short, general guidelines prepared by the CCP Central Committee in the fall prior to the start of a Plan period. More detailed plans are approved by the National People's Congress the following March. These plans establish national priorities and outline how they will be met. Administratively, the Plans result in the development of numerous specific action plans across different levels of administration. These programs evolve over the course of the plan period. As academic Sebastian Heilmann observes, this process is best viewed as a planning coordination and evaluation cycle rather than a unified blueprint.

China's Five-Year Plans have been praised for their efficiency, capabilities and their importance to rapid economic growth, development, corporate finance and industrial policies.

First Plan (1953–1957)

Main article: First five-year plan (China)

Chairman Mao and Various Leaders of the First Five Year Plan - 1956

Having restored a viable economic base, the leadership under Chairman Mao Zedong, Premier Zhou Enlai, and other revolutionary veterans sought to implement what they termed a socialist transformation of China. The First Five-Year Plan was deeply influenced by Soviet methodologies and assistance from Soviet planners. Industrial development was the primary goal. With Soviet assistance in the form of both funds and experts, China began to develop industries from scratch. Consistent with the focus on developing industry, northeast China was the region which received the greatest share of state funds during the First Plan.

The First Five-Year Plan phrased its developmental focus in the terminology of revolution. It attributed the backwards state of China's economy to contradictions between the developing productive forces and the capitalist relations of production. Agriculture, fishing, and forestry would be collectivized. Regarding commercial and services industries, the approach in the first Five-Year Plan was for the government to buy them out, including through coercing reluctant sellers if necessary.

Government control over industry was increased during this period by applying financial pressures and inducements to convince owners of private, modern firms to sell them to the state or convert them into joint public-private enterprises under state control. The Plan strained agricultural production. In terms of economic growth, the First Five-Year Plan was quite successful, especially in those areas emphasized by the Soviet-style development strategy. During this Plan period, China began developing a heavy-industrial base and brought its industrial production above what it had been prior to war. China also raised its agricultural production to above prewar levels, resulting primarily from gains in efficiency brought about by the reorganization and cooperation achieved through cooperative farming. Although urbanization had not been a specific goal of the plan's focus on industrialization, industrialization also prompted extensive urban growth. By 1956, China had completed its socialist transformation of the domestic economy.

Second Plan (1958–1962)

See also: Great Leap Forward

This plan was created to accomplish several tasks, including:

• Expanding heavy industry in China.
• Furthering the cause of socialism by transferring more property to collective ownership.
• Encouraging the economic growth of China through industry, agriculture, handicrafts, transportation and commerce.
• Cultivating cultural and scientific development of the Chinese people.
• Strengthening national defense and improving living standards in China.

The Political Bureau of the CPC had determined that gross value of agricultural products should increase 270%; in fact, the gain was a considerably more modest 35%. The country saw increases in capital construction over those observed during the first Five-Year Plan and also saw significant increases in industry (doubling output value) and income (workers and farmers, increase by as much as 30%).

However, the Great Leap Forward, which diverted millions of agricultural workers into industry, and the great sparrow campaign, which led to an infestation of locusts, as well as unprecedented natural and weather based issues, caused a huge decrease in food production. Simultaneously, rural officials, under huge pressure to meet their quotas, vastly overstated how much grain was available. Thus, a massive nationwide famine ensued.

The policies of the Second Plan's Great Leap Forward departed from the approach in the Soviet-inspired First Plan, which stressed central command and extensive planning. Instead, the approach entailed local areas marshalling all available resources for large projects. In 1960–61, attempts were made to redirect twenty million workers into agricultural production and to reallocate investment into those industrial sectors that could further support agriculture. This shift was also in sharp contrast to the rapid industrialization seen in the First Five-Year Plan.

Third Plan (1966–1970)

Main article: Third five-year plan (China)

The Third Plan was originally due early in 1963, but at that time China's economy was too dislocated, as a result of the failure of the Great Leap Forward and four poor harvests to permit any planned operations. As initially conceived, the Third Five Year Plan emphasized further development in China's already more developed coastal areas and a greater focus on consumer goods. It called for enhancing "eating, clothing, and daily use" items (chi, chuan, yong). During discussions of the Third Five Year Plan, Mao acknowledged that during the Great Leap Forward, "We set revenue too high and extended the infrastructure battlefront too long," and that it was "best to do less and well."

The Plan ultimately called for the prioritization of national defense in the light of a possible big war, actively preparing for conflicts and speeding up construction in three key areas; national defense, science and technology, and industry and transport infrastructure. The turn towards a greater emphasis on developing heavy industries and national defense industries was prompted by the Gulf of Tonkin incident, which increased fears among Chinese leadership that the United States would ultimately invade China. Support among leadership for Mao's proposed Third Front construction increased as a result and changed the direction of the Third Five Year Plan.

Fourth Plan (1971–1975)

The Fourth Five Year Plan sought decentralization and prioritized "small scale, indigenous, and labor intensive" development projects over "large scale, foreign, and capital intensive" development.

Fifth Plan (1976–1980)

The central government stipulated the 1976–1985 Ten Year Plan Outline of Developing National Economy (Draft) in 1975, which included the 5th Five-Year Plan.

In March 1978, the Ten Year Development Outline was amended because the original version in 1975 stipulated that by 1985, steel and petroleum outputs should reach 60 and 250 million tons respectively, and 120 large projects, including 10 steel production bases, nine non-ferrous metal bases, eight coal bases and 10 oil and gas fields, should be built. To achieve these goals, the government would invest 70 billion yuan in infrastructure construction, equaling total national investment over the previous 28 years. These were impossible targets and ran counter to economic development rules.

The Plan put forward suggestions to set up an independent and comparatively complete industrial system and national economic system from 1978 to 1980.

With the implementation of the Plan, considerable success was achieved. In 1977, the gross output value of industry and agriculture reached 505.5 billion yuan, 4.4% above-target and representing an increase of 10.4% compared with the previous year. Gross domestic product for 1978 reached 301 billion yuan, an increase of 12.3% compared with 1977, and an increase of 19.4% compared with 1976.

However, during this period, the Chinese economy developed too quickly, and the very high goals triggered the onset of yet another round of mistakes. In December 1978, the 3rd Plenary Session of the 11th Central Committee of the Chinese Communist Party shifted the work focus of the CCP to modernization. The Session emphasized that the development should follow economic rules and proposed readjustment and reform measures, which indicated that national economic development had entered a new phase, one of exploration and development. In April 1979, the central government formally put forward new principles of readjustment, reform, rectification and improvement.

Sixth Plan (1981–1985)

Main article: Sixth five-year plan (China)

According to China Daily, the 6th Plan was first planned as part of the "Ten Year National Economic Development Plan Outline for 1976–1985" until the State Council decided to redraft the country's mid- and long-term plans in 1980. The 1982 national planning meeting was again mainly focused on the drafting of the Plan. It was only in December that year that the fifth meeting of the 5th National People's Congress officially ratified the Plan.

The Sixth Five-Year Plan was the first to address government policy support for solar PV panel manufacturing. Policy support for solar panel manufacturing has been a part of every Five-Year Plan since.

Seventh Plan (1986–1990)

Main article: Seventh five-year plan (China)

In late September 1985, the Conference of CCP Delegates convened to adopt the "Proposal for the Seventh Five Year Plan" which was set to begin in 1986. The proposal demonstrated a shift from direct government control over enterprises to using indirect macroeconomic controls to "establish a new system for the socialist economy." In March 1986, the State Council submitted "The 7th Five Year Plan for National Economic and Social Development of the People's Republic of China, 1986–1990" to the Fourth Session of the Sixth National People's Congress for review and ratification. It was the first time in China's history that an all-round plan for social and economic development was created at the start of a new five-year plan.

The national goals of the Plan included speeding up development on the coast, with inland regions role's being to "support and accelerate coastal development." During this Plan period, different regions of China were encouraged to develop by leveraging their respective advantages. Coastal regions were instructed to focused on "the restructuring of traditional industries, new industries, and consumer goods production." Western regions were to focus on processing and agriculture. In central regions, energy, construction, and minerals were the focus.

Tenth Plan (2001–2005)

During the 10th Five-Year Plan, the strategic purpose of planning shifted from narrow, quantitative growth targets to coordinating structural and qualitative changes in economic and social growth targets.

The Plan described science, technology, and human resources as decisive areas to improve for China to catch-up with the most advanced countries.

Focuses included growing the services sector, developing domestic economic demand, rural urbanization, and western development.

Environmental sustainability was also addressed. Goals included increasing forest coverage to 18.2%, and the urban green rate to 35%. The total amount of major urban and rural pollutants discharged were targeted for a 10% reduction as compared with 2000, and more measures would be taken to protect and save natural resources.

Eleventh Plan (2006–2010)

Main article: Eleventh five-year plan (China)

The planning philosophy for the 11th Five-Year Plan was significantly shaped by a mid-term evaluation of the 10th Five-Year Plan. The 11th Five-Year Plan introduced a new category of "binding targets" (yueshuxing zhibiao) intended as government promises. These binding targets have since been used especially in non-economic policy areas like environmental protection and land management. Of 22 targets listed in the 11th Five-Year Plan, eight of them were binding targets. These binding targets were incorporated into the criteria for local cadre performance evaluations. The Plan also reflected a change in terminology to the allocation of administrative resourced via "programs" rather than "plans."

Twelfth Plan (2011–2015)

Main article: Twelfth five-year plan (China)

The Twelfth Five-Year Guideline was debated in mid-October 2010 at the fifth plenary session of the 17th Central Committee of the Chinese Communist Party, the same session in which Xi Jinping was selected as Vice Chairman of the Central Military Commission, and the full proposal for the plan was released following the plenum and approved by the National People's Congress on 14 March 2011. The plan shifted emphasis from investment towards consumption and development from urban and coastal areas toward rural and inland areas – initially by developing small cities and greenfield districts to absorb coastal migration. The plan also continued to advocate objectives set out in the Eleventh Five-Year Plan to enhance environmental protection, accelerate the process of opening and reform, and emphasize Hong Kong's role as a center of international finance. It prioritized more equitable wealth distribution, increased domestic consumption, and improved social infrastructure and social safety nets. Improvements in the social safety net were intended to reduce precautionary saving. The plan sought to expand the services industry in order to increase employment and continue urbanization to help raise real wages.

Thirteenth Plan (2016–2020)

Main article: Thirteenth five-year plan (China)

Continuing themes from the Twelfth Five-Year Plan, the Thirteenth Five-Year Plan also sought to boost the services sector, increase urbanization, and expand the social safety net to reduce precautionary savings. It also emphasized innovation, the completion of building a moderately prosperous society, and started the "Made in China 2025" plan.

Fourteenth Plan (2021–2025)

Main article: Fourteenth five-year plan (China)

The 14th Five-Year Plan was drafted during the fifth plenum of the 19th Central Committee held from 26 to 29 October 2020. Han Wenxiu, the deputy director of the Office of the Central Finance and Economic Commission, said CCP general secretary Xi Jinping had personally led the drafting process through multiple meetings of the Politburo, its standing committee, and the drafting panel that he headed.

The Plan was drafted against the backdrop of worsening China–United States relations and the COVID-19 pandemic, which caused China's economy to shrink in the first quarter of 2020 – the first time in 44 years. Continuing themes from the prior two plans, the Thirteenth Five-Year Plan also seeks to boost the services sector, increase urbanization, and expand the social safety net to reduce precautionary savings. To address the aging of China's population, the Plan seeks to expand healthcare and retirement system initiatives. The Plan also emphasizes high-tech innovation.

Energy security of the People's Republic of China

From Wikipedia, the free encyclopedia

https://en.wikipedia.org/wiki/Energy_security_of_the_People%27s_Republic_of_China 

Energy security of the People's Republic of China concerns the need for the People's Republic of China to guarantee itself and its industries long- term access to sufficient energy and raw materials. China has been endeavoring to sign international agreements and secure such supplies; its energy security involves the internal and foreign energy policy of China. Currently, China's energy portfolio consists mainly of domestic coal, oil and gas from domestic and foreign sources, and small quantities of uranium. China has also created a strategic petroleum reserve, to secure emergency supplies of oil for temporary price and supply disruptions. Chinese policy focuses on diversification to reduce oil imports, which used to rely almost exclusively on producers in the Middle East.

Coal supplied most (about 58%) of China’s total energy consumption in 2019, down from 59% in 2018. The second-largest fuel source was petroleum and other liquids, accounting for 20% of the country’s total energy consumption in 2019. Although China has diversified its energy supplies and cleaner burning fuels have replaced some coal and oil use in recent years, hydroelectric sources (8%), natural gas (8%), nuclear power (2%), and other renewables (nearly 5%) accounted for relatively small but growing shares of China’s energy consumption. 4 The Chinese government intends to cap coal use to less than 58% of total primary energy consumption by 2020 in an effort to curtail heavy air pollution that has affected certain areas of the country in recent years. According to China’s estimates, coal accounted for a little less than 58% in 2019, which places the government within its goal. 5 Natural gas, nuclear power, and renewable energy consumption have increased during the past few years to offset the drop in coal use.

According to Professor Zha Daojiong, China's dependence on foreign sources of energy is not a threat to China's energy security, since the world energy market is not opposed to China's pursuit of growth and prosperity. The key issue is actually internal: growing internal consumption without energy efficiency threatens both China's growth and world oil markets. Chinese imports are a new determinant encouraging oil price rises on the world market, a concern to developed countries. The international community advocates a move toward energy efficiency and more transparency in China's quest for energy worldwide, to confirm China's responsibility as a member of the international community. Energy efficiency is the only way to avoid excessive Chinese demands on oil at the expense of industrialized and industrializing countries. International projects and technology transfers are ongoing, improving China's energy consumption and benefit the whole energy-importing world; this will also calm Western-Chinese diplomatic tensions. China is trying to establish long-term energy security by investment in oil and gas fields abroad and by diversifying its providers.

Background

Chinese oil reserves

Thanks to the transfer of Soviet oil extraction technologies prior to July 1960 and domestic reserves such as the Daqing oil field, the PRC became oil self-sufficient in 1963. A US-led embargo isolated the Chinese oil industry from 1950 to 1970, preventing it from selling on the world oil market. After the embargo was lifted, China reactivated its links with Japan and other industrialized nations thanks to its oil exports, which helped bring in foreign currencies and fund key industrial plants and technologies for developing its own export-oriented economy. Chinese oil exports peaked in 1985 at 30 million tons. Rapid reforms, in turn, increased domestic oil demand and led China to become a net oil importer in 1993, and net crude oil importer in 1996.

Since 1996 Chinese oil production has slowly and continuously decreased, while demand and imports have steadily increased. Future Chinese oil reserves (such as the Tarim basin) are difficult to extract, requiring specific technologies as well as the construction of pipelines thousands of kilometers long. As a result, such reserves would be very difficult to develop and not cost-effective, given current market prices.

Issues that China faces

Natural gas production in China (red) has not kept up with consumption (black), requiring increased imports of gas.

Main articles: Energy policy of China and Renewable energy in China

China's demand for oil

Oil production in China (red) has not kept up with rapidly increasing demand (black).

China is the world’s largest crude oil importer and the second-largest crude oil consumer. According to U.S. Energy Information Administration data, China’s crude oil imports in 2019 increased to an average of 10.1 million barrels per day (b/d), an increase of 0.9 million b/d from the 2018 average.

China’s top five crude suppliers, Saudi Arabia, Russia, Iraq, Angola, and Brazil, generated nearly 60% of Chinese crude oil imports for 2019.

China accounts for 40% of the 2004 oil-consumption increase, and thus is a key part of the cycle which had led to the oil price increase worldwide. China's import dependence remains at 60% as of 2014. In 2005, a campaign to increase energy efficiency was launched without official Ministry of Energy approval; since the campaign was sporadic, this objective seems hard to meet. Zha Daojiong encouraged increased management of oil and energy in China, noting that "It is fair to say that the threat from ineffective energy industry governance is probably as great as that from the international energy market.". A projection that China would reach South Korean levels of per-capita oil consumption in 30 years, combined with the current average global decline in production, could mean that up to 44 Mbbl/d (7,000,000 m³/d) (barrels per day) in production would have to be found in the next decade to keep up with increased demand and production declines. That would be the equivalent of roughly five times Saudi Arabia's production. Superimpose a production plateau of 100 Mbbl/d (16,000,000 m³/d), and significant real-price increases would be necessary to balance supply and demand. Such increases might have severe effects on the growth of emerging market economies such as China's.

Nuclear and coal

Nuclear power in China accounts for approximately 4.9% of China's electricity, this compares to about 20% in the United States. China still mainly relies on coal for electricity. China is first in the world in both coal production and consumption, which has sparked environmental concerns. In order to achieve environmental targets in combating pollution and global warming, China must ultimately improve its coal efficiency and switch to alternative energy sources.

Limitations of pipelines and stocks

China’s natural gas consumption rose by 9% in 2019 to 10.8 trillion cubic feet (Tcf) per year from 9.9 Tcf in 2018. China’s NOCs produced an estimated 6.3 cf of natural gas in 2019, 8% higher than in 2018

Three gas lines from Turkmenistan were completed in 2009, 2010 and 2014 respectively, bringing 1.9 Tcf a year China.

The Power of Siberia pipeline started delivering gas in Dec 2020. By 2025 it should deliver 2.1 Tcf a year to China.

China became the largest importer of LNG at the end of 2021. The U.S. Energy Information Administration (EIA) said China’s LNG imports averaged 10.3 Bcf/d between January and October – a 24% increase over the same period last year. China’s U.S. LNG imports increased by 0.9 Bcf/d from January to October to about 1.1 Bcf/d, ranking the U.S. second behind Australia, which provided 40% of China’s LNG imports during the period at an average of 4.1 Bcf/d. Qatar and Malaysia supplied China with amounts similar to those of the United States. All three countries provided about 11% of China’s total LNG imports through October. Another 19 countries rounded out China’s LNG supplies.

China's eastern and southern regions have chronic energy shortages, causing blackouts and limiting economic growth. For supplying these regions, liquefied natural gas from Australia and Indonesia is more feasible and cheaper to import than the Tarim basin pipeline. However, the first West–East Gas Pipeline from Xinjiang to Shanghai was commissioned in 2004, and construction of the second pipeline from Xinjiang to Guangzhou in Guangdong began in 2008.

Sinopec accounts for 80% of Chinese oil imports. Refinery capacity is continuously strained, and perennially lags behind fast domestic-demand growth. China has had to rely on entrepôt refineries located in Singapore, Japan and Korea. Oil and gas exploration in the Tarim Basin is ongoing. However, developing this potential reserve is currently not cost-effective due to technological limitations coupled with fluctuations in world oil prices. Therefore, this is considered by some as a last-resort option.

In China, the gas price is not market-driven, which causes uncertainty in the production process.

Energy efficiency

A key point for China's energy-security goal of reducing oil imports is to improve the efficiency of its domestic energy markets by accelerating pricing, regulatory and other reforms. China is actively looking for smart-energy technology.

Foreign relations

Chinese oil imports by region of origin

	1990	2000	2004	2019
Mdl East	39.4%	53.5%	45.4%	44%
Africa	0%	23%	28.7%	19%
Asia Pacific	60.6%	15.1%	4.5%	3%
Russia	NA	NA	7%	15%
Western Hemisphere	0%	7.2%	14.3%	15%
Sources: CQE, p12-15; CES, p49. EIA

Middle East

On the issue of energy security, China relies mainly on Persian Gulf exports. In contrast with the US, China is not associated with the Arab–Israeli conflicts and may focus simply on oil supply from an economic standpoint. The increase in Chinese dependence on Persian Gulf oil also means an associated increasing economic dependence on Arabian exporters, who will probably not join hands to block exports to China.

Chinese dependence on the Middle East is also a cause of concern for the US. In 2004, when the Bush administration actively discouraged oil companies from investing in Iran, the Chinese company Sinopec did not comply with its call.

Recently, China has changed its anti-Western diplomatic stance to a softer, global, more efficient diplomacy with a focus on energy and raw-materials security. In post-2003 Iraq, China does its best to comply with UN sanctions.

Japan and Korea

When China became an oil importer during the 1990s, its relations with neighboring countries (as exporter to East Asia and importer of Korean and Japanese oil) changed. Its main oil provider changed in a few years from domestic production, to East Asian production, and then to Mideast production. On the other hand, despite insufficient domestic oil output China does its best to stabilize exports to Japan and Korea. China endeavors to continue energy relationships it has created with developed nations, since they contribute to China's energy security with investment and technology. More Chinese oil output is in Japanese, Korean, Chinese, and world interests. Since China lacks strategic entrepôt refineries, it relies heavily on refineries in Singapore, Japan, and Korea.

Taiwan

China's dependence on foreign oil weakens its ability to pressure Taiwan, since a conflict may trigger a US oil embargo as a consequence. Since Sudan is pro-Chinese and Chad was pro-Taiwan (and an oil producer since 2003), China had an interest in replacing Chad's president Idriss Déby with a pro-Chinese leader. The FUC Chad rebellion, based in Sudan and aiming to overthrow the pro-Taiwanese Déby, seems to have received Chinese diplomatic support as well as weapons and Sudanese oil. The 2006 Chadian coup d'état attempt failed after French Air Force intervention, but Déby then switched his friendship to Beijing; the field defeat became a Chinese strategic victory.

Russia

In February 2009, Russia and China signed an agreement in which a spur of the Eastern Siberia–Pacific Ocean oil pipeline to China would be built and Russia would supply China with 15 million tonnes of oil (300,000 barrels (48,000 m³) per day) each year for 20 years, in exchange for a loan worth US$25 billion to Russian companies Transneft and Rosneft for pipeline and oilfield development.

Australia

On August 19, 2009, Chinese petroleum company PetroChina signed an A$50 billion deal with American multinational petroleum company ExxonMobil to purchase liquefied natural gas from the Gorgon field in Western Australia; this was believed to be the largest contract ever signed between China and America – ensuring China a steady supply of LPG fuel for 20 years. This agreement has been formalised despite relations between Australia and China being at their lowest point in years following the Rio Tinto espionage case and the granting of a visa to Rebiya Kadeer to visit Australia.

Central Asia

China has constructed an oil pipeline from Kazakhstan and started construction of a Central Asia–China gas pipeline.

Sea lanes

Ratification of the Law of the Sea Treaty is linked to China's need to secure its oil and raw materials shipping from the Middle East, Africa, and Europe, since those materials have to pass through the Strait of Malacca and the Red Sea.

Oil diplomacy

The appearance of China on the world energy scene is somewhat disturbing for developed nations. China's relative energy inexperience also raises diplomatic difficulties. Strengthening ties with oil producers such as Iran, Sudan, Uzbekistan, Angola and Venezuela also raised concerns for U.S. and other Western diplomacy, since several of these countries are known to be anti-American and/or known for human rights abuses, political censorship, and widespread corruption. These moves seem to challenge Western powers, by strengthening anti-Western countries. But this is unlikely; as a developing consumer economy, China does not have much of a choice in its sources of supply.

Poor communication

It is claimed that Chinese oil companies are unaccustomed to political risks and avoiding diplomatic conflict. In any case, the Chinese government will still be seen as ultimately responsible for conflict resolution. Communication has also been a weak point for Chinese companies. Lack of transparency in cases such as Chinese involvement in Sudan have raised concern in the US, until it was revealed that most of the oil produced was sold on international markets. Lack of cooperation with other major oil companies has led to business clashes, spilling into the diplomatic arena when both sides call their respective governments to support their interests (CNOOC versus Chevron-Texaco for Unocal, for example).

Kevlar

From Wikipedia, the free encyclopedia

https://en.wikipedia.org/wiki/Kevlar 

 

Kevlar

Names
IUPAC name Poly(azanediyl-1,4-phenyleneazanediylterephthaloyl)
Identifiers
CAS Number	24938-64-5
ChemSpider	none
Properties
Chemical formula	[-CO-C6H4-CO-NH-C6H4-NH-]n

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.

Kevlar has many applications, ranging from bicycle tires and racing sails to bulletproof vests, all due to its high tensile strength-to-weight ratio; by this measure it is five times stronger than steel. It is also used to make modern marching drumheads that withstand high impact; and for mooring lines and other underwater applications.

A similar fiber called Twaron with the same chemical structure was developed by Akzo in the 1970s; commercial production started in 1986, and Twaron is now manufactured by Teijin.

History

Inventor of Kevlar, Stephanie Kwolek, an American chemist

Poly-paraphenylene terephthalamide (K29) – branded Kevlar – was invented by the American chemist Stephanie Kwolek while working for DuPont, in anticipation of a gasoline shortage. In 1964, her group began searching for a new lightweight strong fiber to use for light, but strong, tires. The polymers she had been working with at the time, poly-p-phenylene-terephthalate and polybenzamide, formed liquid crystals while in solution, something unique to those polymers at the time.

The solution was "cloudy, opalescent upon being stirred, and of low viscosity" and usually was thrown away. However, Kwolek persuaded the technician, Charles Smullen, who ran the spinneret, to test her solution, and was amazed to find that the fiber did not break, unlike nylon. Her supervisor and her laboratory director understood the significance of her discovery and a new field of polymer chemistry quickly arose. By 1971, modern Kevlar was introduced. However, Kwolek was not very involved in developing the applications of Kevlar.

In 1971, Lester Shubin, who was then the Director of Science and Technology for the National Institute for Law Enforcement and Criminal Justice, suggested using Kevlar to replace nylon in bullet-proof vests. Prior to the introduction of Kevlar, flak jackets made of nylon had provided much more limited protection to users. Shubin later recalled how the idea developed: "We folded it over a couple of times and shot at it. The bullets didn't go through." In tests, they strapped Kevlar onto anesthetized goats and shot at their hearts, spinal cords, livers and lungs. They monitored the goats' heart rate and blood gas levels to check for lung injuries. After 24 hours, one goat died and the others had wounds that were not life threatening. Shubin received a $5 million grant to research the use of the fabric in bullet-proof vests.

Kevlar 149 was invented by Dr. Jacob Lahijani of Dupont in the 1980s.

Production

The reaction of 1,4-phenylene-diamine (para-phenylenediamine) with terephthaloyl chloride yielding Kevlar

Kevlar is synthesized in solution from the monomers 1,4-phenylene-diamine (para-phenylenediamine) and terephthaloyl chloride in a condensation reaction yielding hydrochloric acid as a byproduct. The result has liquid-crystalline behavior, and mechanical drawing orients the polymer chains in the fiber's direction. Hexamethylphosphoramide (HMPA) was the solvent initially used for the polymerization, but for safety reasons, DuPont replaced it by a solution of N-methyl-pyrrolidone and calcium chloride. As this process had been patented by Akzo (see above) in the production of Twaron, a patent war ensued.

Kevlar production is expensive because of the difficulties arising from using concentrated sulfuric acid, needed to keep the water-insoluble polymer in solution during its synthesis and spinning.

Several grades of Kevlar are available:

• Kevlar K-29 – in industrial applications, such as cables, asbestos replacement, tires, and brake linings.
• Kevlar K49 – high modulus used in cable and rope products.
• Kevlar K100 – colored version of Kevlar
• Kevlar K119 – higher-elongation, flexible and more fatigue resistant
• Kevlar K129 – higher tenacity for ballistic applications
• Kevlar K149 – highest tenacity for ballistic, armor, and aerospace applications
• Kevlar AP – 15% higher tensile strength than K-29
• Kevlar XP – lighter weight resin and KM2 plus fiber combination
• Kevlar KM2 – enhanced ballistic resistance for armor applications

The ultraviolet component of sunlight degrades and decomposes Kevlar, a problem known as UV degradation, and so it is rarely used outdoors without protection against sunlight.

Structure and properties

Molecular structure of Kevlar: bold represents a monomer unit, dashed lines indicate hydrogen bonds.

When Kevlar is spun, the resulting fiber has a tensile strength of about 3,620 MPa (525,000 psi), and a relative density of 1.44 (0.052 lb/in³). The polymer owes its high strength to the many inter-chain bonds. These inter-molecular hydrogen bonds form between the carbonyl groups and NH centers. Additional strength is derived from aromatic stacking interactions between adjacent strands. These interactions have a greater influence on Kevlar than the van der Waals interactions and chain length that typically influence the properties of other synthetic polymers and fibers such as ultra-high-molecular-weight polyethylene. The presence of salts and certain other impurities, especially calcium, could interfere with the strand interactions and care is taken to avoid inclusion in its production. Kevlar's structure consists of relatively rigid molecules which tend to form mostly planar sheet-like structures rather like silk protein.

Thermal properties

Kevlar maintains its strength and resilience down to cryogenic temperatures (−196 °C (−320.8 °F)): in fact, it is slightly stronger at low temperatures. At higher temperatures the tensile strength is immediately reduced by about 10–20%, and after some hours the strength progressively reduces further. For example: enduring 160 °C (320 °F) for 500 hours, its strength is reduced by about 10%; and enduring 260 °C (500 °F) for 70 hours, its strength is reduced by about 50%.

Applications

Science

Kevlar is often used in the field of cryogenics for its low thermal conductivity and high strength relative to other materials for suspension purposes. It is most often used to suspend a paramagnetic salt enclosure from a superconducting magnet mandrel in order to minimize any heat leaks to the paramagnetic material. It is also used as a thermal standoff or structural support where low heat leaks are desired.

A thin Kevlar window has been used by the NA48 experiment at CERN to separate a vacuum vessel from a vessel at nearly atmospheric pressure, both 192 cm (76 in) in diameter. The window has provided vacuum tightness combined with reasonably small amount of material (only 0.3% to 0.4% of radiation length).

Protection

Pieces of a Kevlar helmet used to help absorb the blast of a grenade

Kevlar is a well-known component of personal armor such as combat helmets, ballistic face masks, and ballistic vests. The PASGT helmet and vest used by United States military forces, use Kevlar as a key component in their construction. Other military uses include bulletproof face masks and spall liners used to protect the crews of armoured fighting vehicles. Nimitz-class aircraft carriers use Kevlar reinforcement in vital areas. Civilian applications include: high heat resistance uniforms worn by firefighters, body armour worn by police officers, security, and police tactical teams such as SWAT.

Kevlar is used to manufacture gloves, sleeves, jackets, chaps and other articles of clothing designed to protect users from cuts, abrasions and heat. Kevlar-based protective gear is often considerably lighter and thinner than equivalent gear made of more traditional materials.

Kevlar is a very popular material for racing canoes.

It is used for motorcycle safety clothing, especially in the areas featuring padding such as the shoulders and elbows. In the sport of fencing it is used in the protective jackets, breeches, plastrons and the bib of the masks. It is increasingly being used in the peto, the padded covering which protects the picadors' horses in the bullring. Speed skaters also frequently wear an under-layer of Kevlar fabric to prevent potential wounds from skates in the event of a fall or collision.

Sport

In kyudo, or Japanese archery, it may be used for bow strings, as an alternative to the more expensive hemp. It is one of the main materials used for paraglider suspension lines. It is used as an inner lining for some bicycle tires to prevent punctures. In table tennis, plies of Kevlar are added to custom ply blades, or paddles, in order to increase bounce and reduce weight. Tennis racquets are sometimes strung with Kevlar. It is used in sails for high performance racing boats.

In 2013, with advancements in technology, Nike used Kevlar in shoes for the first time. It launched the Elite II Series, with enhancements to its earlier version of basketball shoes by using Kevlar in the anterior as well as the shoe laces. This was done to decrease the elasticity of the tip of the shoe in contrast to the nylon conventionally used, as Kevlar expanded by about 1% against nylon which expanded by about 30%. Shoes in this range included LeBron, HyperDunk and Zoom Kobe VII. However these shoes were launched at a price range much higher than average cost of basketball shoes. It was also used in the laces for the Adidas F50 adiZero Prime football boot.

Several companies, including Continental AG, manufacture cycle tires with Kevlar to protect against punctures.

Folding-bead bicycle tires, introduced to cycling by Tom Ritchey in 1984, use Kevlar as a bead in place of steel for weight reduction and strength. A side effect of the folding bead is a reduction in shelf and floor space needed to display cycle tires in a retail environment, as they are folded and placed in small boxes.

Music

Kevlar has also been found to have useful acoustic properties for loudspeaker cones, specifically for bass and mid range drive units. Additionally, Kevlar has been used as a strength member in fiber optic cables such as the ones used for audio data transmissions.

Kevlar can be used as an acoustic core on bows for string instruments. Kevlar's physical properties provide strength, flexibility, and stability for the bow's user. To date, the only manufacturer of this type of bow is CodaBow.

Kevlar is also presently used as a material for tailcords (a.k.a. tailpiece adjusters), which connect the tailpiece to the endpin of bowed string instruments.

Kevlar is sometimes used as a material on marching snare drums. It allows for an extremely high amount of tension, resulting in a cleaner sound. There is usually a resin poured onto the Kevlar to make the head airtight, and a nylon top layer to provide a flat striking surface. This is one of the primary types of marching snare drum heads. Remo's Falam Slam patch is made with Kevlar and is used to reinforce bass drum heads where the beater strikes.

Kevlar is used in the woodwind reeds of Fibracell. The material of these reeds is a composite of aerospace materials designed to duplicate the way nature constructs cane reed. Very stiff but sound absorbing Kevlar fibers are suspended in a lightweight resin formulation.

Motor vehicles

Kevlar is sometimes used in structural components of cars, especially high-value performance cars such as the Ferrari F40.

The chopped fiber has been used as a replacement for asbestos in brake pads. Aramids such as Kevlar release less airborne fibres than asbestos brakes and do not have the carcinogenic properties associated with asbestos.

Other uses

Fire poi on a beach in San Francisco

Kevlar mooring line

Wicks for fire dancing props are made of composite materials with Kevlar in them. Kevlar by itself does not absorb fuel very well, so it is blended with other materials such as fiberglass or cotton. Kevlar's high heat resistance allows the wicks to be reused many times.

Kevlar is sometimes used as a substitute for Teflon in some non-stick frying pans.

Kevlar fiber is used in rope and in cable, where the fibers are kept parallel within a polyethylene sleeve. The cables have been used in suspension bridges such as the bridge at Aberfeldy, Scotland. They have also been used to stabilize cracking concrete cooling towers by circumferential application followed by tensioning to close the cracks. Kevlar is widely used as a protective outer sheath for optical fiber cable, as its strength protects the cable from damage and kinking. When used in this application it is commonly known by the trademarked name Parafil.

Kevlar was used by scientists at Georgia Institute of Technology as a base textile for an experiment in electricity-producing clothing. This was done by weaving zinc oxide nanowires into the fabric. If successful, the new fabric will generate about 80 milliwatts per square meter.

A retractable roof of over 60,000 sq ft (5,600 m²) of Kevlar was a key part of the design of the Olympic Stadium, Montreal for the 1976 Summer Olympics. It was spectacularly unsuccessful, as it was completed 10 years late and replaced just 10 years later in May 1998 after a series of problems.

Kevlar can be found as a reinforcing layer in rubber bellows expansion joints and rubber hoses, for use in high temperature applications, and for its high strength. It is also found as a braid layer used on the outside of hose assemblies, to add protection against sharp objects.

Some cellphones (including the Motorola RAZR Family, the Motorola Droid Maxx, OnePlus 2 and Pocophone F1) have a Kevlar backplate, chosen over other materials such as carbon fiber due to its resilience and lack of interference with signal transmission.

The Kevlar fiber/epoxy matrix composite materials can be used in marine current turbines (MCT) or wind turbines due to their high specific strength and light weight compared to other fibers.

Composite materials

Aramid fibers are widely used for reinforcing composite materials, often in combination with carbon fiber and glass fiber. The matrix for high performance composites is usually epoxy resin. Typical applications include monocoque bodies for Formula 1 cars, helicopter rotor blades, tennis, table tennis, badminton and squash rackets, kayaks, cricket bats, and field hockey, ice hockey and lacrosse sticks.

Kevlar 149, the strongest fiber and most crystalline in structure, is an alternative in certain parts of aircraft construction. The wing leading edge is one application, Kevlar being less prone than carbon or glass fiber to break in bird collisions.