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117-420: A shinai ( 竹刀 ) is a Japanese sword typically made of bamboo used for practice and competition in kendō . Shinai are also used in other martial arts, but may be styled differently from kendō shinai , and represented with different characters . The light, soft wood used in a shinai distinguishes it from other wooden swords such as a bokuto (木刀) , usually called a bokken (木剣) outside Japan, which
234-424: A knife or dagger , is attached to a hilt and can be straight or curved. A thrusting sword tends to have a straighter blade with a pointed tip. A slashing sword is more likely to be curved and to have a sharpened cutting edge on one or both sides of the blade. Many swords are designed for both thrusting and slashing. The precise definition of a sword varies by historical epoch and geographic region. Historically,
351-424: A polymer blend , such as high impact polystyrene . Large companies may do their own compounding prior to production, but some producers have it done by a third party. Companies that specialize in this work are known as Compounders. The compounding of thermosetting plastic is relatively straightforward; as it remains liquid until it is cured into its final form. For thermosoftening materials, which are used to make
468-434: A prop in professional wrestling , where they are often referred to as kendo sticks or Singapore canes . Wrestlers are typically struck across the back, stomach, legs and arms, though some are struck in the head or face, sometimes depending upon the wrestling promotion where the match is taking place. Sword A sword is an edged, bladed weapon intended for manual cutting or thrusting. Its blade, longer than
585-441: A tsuba , like Kashima Shinden Jikishinkage-ryū does. In Shinkage-ryū , the sleeve is lacquered Kamakura Red, and rather than covering the entire length, is tied off at the non-split end. This particular kind of fukuro-shinai is also called a hikihada ( 蟇肌 ) , or toad-skin shinai . The name comes from how the leather looks after lacquering; the sleeves are actually made of cow or horse-hide. Shinai are commonly used as
702-472: A Japanese sword and is made from a single piece of wood. However, both shinai and bokken are used in kendo . The slats of a shinai are usually made from dried bamboo . Some may also be treated by smoking them, or soaking them in resin . Shinai slats are also made of carbon fibre , reinforced resin, or other approved alternative materials. The shinai comprises four slats known as take ( 竹 ) , which are held together by three leather fittings:
819-512: A conductivity of up to 80 kS/cm in stretch-oriented polyacetylene , has been achieved, it does not approach that of most metals. For example, copper has a conductivity of several hundred kS/cm. Biodegradable plastics are plastics that degrade (break down) upon exposure to sunlight or ultra-violet radiation ; water or dampness; bacteria; enzymes; or wind abrasion. Attack by insects, such as waxworms and mealworms, can also be considered as forms of biodegradation. Aerobic degradation requires that
936-564: A court rank in Constantinople ), and from this time, the term longsword is applied to swords comparatively long for their respective periods. Swords from the Parthian and Sassanian Empires were quite long, the blades on some late Sassanian swords being just under a metre long. Swords were also used to administer various physical punishments , such as non-surgical amputation or capital punishment by decapitation . The use of
1053-467: A duel but fairly ineffective when used in a slashing or chopping motion. A well aimed lunge and thrust could end a fight in seconds with just the sword's point, leading to the development of a fighting style which closely resembles modern fencing. Slashing swords such as the sabre and similar blades such as the cutlass were built more heavily and were more typically used in warfare. Built for slashing and chopping at multiple enemies, often from horseback,
1170-630: A finished plastic may be non-toxic, the monomers used in the manufacture of its parent polymers may be toxic. In some cases, small amounts of those chemicals can remain trapped in the product unless suitable processing is employed. For example, the World Health Organization 's International Agency for Research on Cancer (IARC) has recognized vinyl chloride , the precursor to PVC, as a human carcinogen. Some plastic products degrade to chemicals with estrogenic activity. The primary building block of polycarbonates, bisphenol A (BPA),
1287-664: A general Urnfield background), and survives well into the Iron Age, with a life-span of about seven centuries. During its lifetime, metallurgy changed from bronze to iron , but not its basic design. Naue II swords were exported from Europe to the Aegean, and as far afield as Ugarit , beginning about 1200 BC, i.e. just a few decades before the final collapse of the palace cultures in the Bronze Age collapse . Naue II swords could be as long as 85 cm, but most specimens fall into
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#17327724842171404-420: A heavier sword. This also makes shinai popular in producing movies and television shows; a prop shinai with a thin metal covering can look similar to a metal sword, while allowing cinematic, showy strikes that are nevertheless fairly safe to perform. The word " shinai " is derived from the verb shinau ( 撓う ) , meaning "to bend, to flex", and was originally short for shinai-take (flexible bamboo). Shinai
1521-419: A hilt (tsuka), or handle wrapping ( tsuka-gawa ( 柄皮 ) ); a fitting at the tip ( saki-gawa ( 先皮 ) ) and a leather strip ( naka-yui ( 中結 ) ) that binds the four slats. The parts are all secured with a string ( tsuru ( 弦 ) ). The nakayui is tied about one-third of the length of the exposed bamboo from the tip . This holds the slats together and also marks the proper kendo striking portion of
1638-408: A large molecular weight, they are biochemically inert. Plastic products contain a variety of additives, however, some of which can be toxic. For example, plasticizers like adipates and phthalates are often added to brittle plastics like PVC to make them pliable enough for use in food packaging, toys, and many other items. Traces of these compounds can leach out of the product. Owing to concerns over
1755-491: A large, decorative mount allowing it to be suspended from a belt on the wearer's right side. Because of this, it is assumed that the sword was intended to be drawn with the blade pointing downwards ready for surprise stabbing attacks. In the 12th century, the Seljuq dynasty had introduced the curved shamshir to Persia, and this was in extensive use by the early 16th century. Chinese iron swords made their first appearance in
1872-443: A long shinai called the daitō ( 大刀 ) , which is usually held in the right hand, and a shorter shinai , called the shōtō ( 小刀 ) , which is usually held in the left hand. The holding position can be switched, however, with the daitō in the left hand and the shōtō in the right. The daitō is shorter and lighter than a shinai used in the ittō style of kendō . Specifications for shinai used in kendō competitions that follow
1989-410: A manner considered most appropriate by one's style, dōjō , or sensei . Many people believe that oiling and sanding a shinai prior to its first use, and then periodically during use, can greatly extend its life. However, some disagreement exists on what is considered proper shinai care. To properly inspect a shinai , one first examines the area around the datotsu-bu , inspecting all sides of
2106-417: A material with inconsistent properties, which can be unappealing to industry. For example, mixing different colored plastics with different plastic colorants together can produce a discolored or brown material and for this reason plastic is usually sorted by both polymer type and color before recycling. Absence of transparency and reporting across the value chain often results in lack of knowledge concerning
2223-500: A mixture of private and state-owned enterprises. Roughly half of all production takes place in East Asia, with China being the largest single producer. Major international producers include: Historically, Europe and North America have dominated global plastics production. However, since 2010 Asia has emerged as a significant producer, with China accounting for 31% of total plastic resin production in 2020. Regional differences in
2340-486: A new disease caused solely by plastics, was discovered in seabirds. The birds identified as having the disease have scarred digestive tracts from ingesting plastic waste. "When birds ingest small pieces of plastic, they found, it inflames the digestive tract. Over time, the persistent inflammation causes tissues to become scarred and disfigured, affecting digestion, growth and survival." Pure plastics have low toxicity due to their insolubility in water, and because they have
2457-692: A particular purpose. Examples include thermoplastics , thermosets , conductive polymers , biodegradable plastics , engineering plastics and elastomers . One important classification of plastics is the degree to which the chemical processes used to make them are reversible or not. Thermoplastics do not undergo chemical change in their composition when heated and thus can be molded repeatedly. Examples include polyethylene (PE), polypropylene (PP), polystyrene (PS), and polyvinyl chloride (PVC). Thermosets, or thermosetting polymers, can melt and take shape only once: after they have solidified, they stay solid. If reheated, thermosets decompose rather than melt. In
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#17327724842172574-674: A pattern of more regularly spaced atoms, such as high-density polyethylene (HDPE), polybutylene terephthalate (PBT), and polyether ether ketone (PEEK). However, some plastics are partially amorphous and partially crystalline in molecular structure, giving them both a melting point and one or more glass transitions (the temperature above which the extent of localized molecular flexibility is substantially increased). These so-called semi-crystalline plastics include polyethylene, polypropylene, polyvinyl chloride, polyamides (nylons), polyesters and some polyurethanes. Intrinsically Conducting Polymers (ICP) are organic polymers that conduct electricity. While
2691-403: A practice weapon that was less dangerous than bokutō ( 木刀 ) , the hard wooden swords they were previously using. This is also the motivation behind the development of bōgu ( 防具 ) , the armour that protects the kendoka . Due to its lighter weight compared to a bokken or a metal katana , a shinai can be wielded in a fashion that allows quicker strikes than would be practicable with
2808-428: A rubber ring tsuba-dome ( 鍔止め ) . The shinai is useful as a practice sword to simulate the weight and feel of a katana or bokken without injuring the user or the target. Upon impact the bundled slats dissipate the force of the strike by flexing/bending along the length of the blade, and expanding slightly, along its cross-sectional area (stress = force/unit area). As a result of this lack of rigidity, along with
2925-573: A sword, an honourable weapon, was regarded in Europe since Roman times as a privilege reserved for the nobility and the upper classes. In the first millennium BC, the Persian armies used a sword that was originally of Scythian design called the akinaka ( acinaces ). However, the great conquests of the Persians made the sword more famous as a Persian weapon, to the extent that the true nature of
3042-674: A total length of more than 100 cm (39 in). These are the "type A" swords of the Aegean Bronze Age . One of the most important, and longest-lasting, types of swords of the European Bronze Age was the Naue II type (named for Julius Naue who first described them), also known as Griffzungenschwert (lit. "grip-tongue sword"). This type first appears in c. the 13th century BC in Northern Italy (or
3159-519: A turnover of more than 360 billion euros per year. In China in 2016 there were over 15,000 plastic manufacturing companies, generating more than US$ 366 billion in revenue. In 2017, the global plastics market was dominated by thermoplastics – polymers that can be melted and recast. Thermoplastics include polyethylene (PE), polyethylene terephthalate (PET), polypropylene (PP), polyvinyl chloride (PVC), polystyrene (PS) and synthetic fibers, which together represent 86% of all plastics. Plastic
3276-472: A two-handed sword for a more powerful blow. In the Middle Ages, the sword was often used as a symbol of the word of God . The names given to many swords in mythology , literature , and history reflected the high prestige of the weapon and the wealth of the owner. From around 1300 to 1500, in concert with improved armour , innovative sword designs evolved more and more rapidly. The main transition
3393-1040: A variant called the M1941 Cutlass as a makeshift jungle machete during the Pacific War . Non-European weapons classified as swords include single-edged weapons such as the Middle Eastern scimitar , the Chinese dao and the related Japanese katana . The Chinese jiàn 剑 is an example of a non-European double-edged sword , like the European models derived from the double-edged Iron Age sword . The first weapons that can be described as "swords" date to around 3300 BC. They have been found in Arslantepe , Turkey, are made from arsenical bronze , and are about 60 cm (24 in) long. Some of them are inlaid with silver . The sword developed from
3510-594: A variety of shapes: films, fibers, plates, tubes, bottles and boxes, among many others. Plasticity also has a technical definition in materials science outside the scope of this article; it refers to the non-reversible change in form of solid substances. Most plastics contain organic polymers. The vast majority of these polymers are formed from chains of carbon atoms, with or without the attachment of oxygen, nitrogen or sulfur atoms. These chains comprise many repeating units formed from monomers . Each polymer chain consists of several thousand repeating units. The backbone
3627-459: A wall. Some instructors require the base ( kashira ) of the handle ( tsuka ) on the floor and the tip ( kissaki ) leaning against the wall. In kendo, the shinai is treated in the same way as a edged or bladed weapon , like an actual metal sword, and competitors are trained to think of it as a dangerous instrument if misused. When a shinai is placed on the floor, it is considered poor etiquette to step over it. In kendo competitions that follow
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3744-921: A wide range of synthetic or semi-synthetic materials that use polymers as a main ingredient. Their plasticity makes it possible for plastics to be molded , extruded or pressed into solid objects of various shapes. This adaptability, plus a wide range of other properties, such as being lightweight, durable, flexible, and inexpensive to produce, has led to their widespread use. Plastics typically are made through human industrial systems. Most modern plastics are derived from fossil fuel-based chemicals like natural gas or petroleum ; however, recent industrial methods use variants made from renewable materials, such as corn or cotton derivatives. Between 1950 and 2017 9.2 billion metric tons of plastic are estimated to have been made; more than half of this has been produced since 2004. In 2020, 400 million tons of plastic were produced. If global trends on plastic demand continue, it
3861-460: Is a "sword" with a flexible whip-like blade. In Indonesia , the images of Indian style swords can be found in Hindu gods statues from ancient Java circa 8th to 10th century. However the native types of blade known as kris , parang , klewang and golok were more popular as weapons. These daggers are shorter than a sword but longer than a common dagger. Plastic Plastics are
3978-403: Is a global treaty to protect human health and the environment from chemicals that remain intact in the environment for long periods, become widely distributed geographically, accumulate in the fatty tissue of humans and wildlife, and have harmful impacts on human health or on the environment. Other additives proven to be harmful such as cadmium , chromium , lead and mercury (regulated under
4095-531: Is an estrogen-like endocrine disruptor that may leach into food. Research in Environmental Health Perspectives finds that BPA leached from the lining of tin cans, dental sealants and polycarbonate bottles can increase the body weight of lab animals' offspring. A more recent animal study suggests that even low-level exposure to BPA results in insulin resistance, which can lead to inflammation and heart disease. As of January 2010,
4212-555: Is as packaging materials, but they are used in a wide range of other sectors, including: construction (pipes, gutters, door and windows), textiles ( stretchable fabrics , fleece ), consumer goods (toys, tableware, toothbrushes), transportation (headlights, bumpers, body panels , wing mirrors ), electronics (phones, computers, televisions) and as machine parts. In optics, plastics are used to manufacture aspheric lenses. Additives are chemicals blended into plastics to change their performance or appearance, making it possible to alter
4329-488: Is burned, especially when burning is uncontrolled or takes place in low- technology incinerators, as is common in many developing countries. Incomplete combustion can cause emissions of hazardous substances such as acid gases and ash which can contain persistent organic pollutants (POPs) such as dioxins . A number of additives identified as hazardous to humans and/or the environment are regulated internationally. The Stockholm Convention on Persistent Organic Pollutants (POPs)
4446-496: Is estimated that annual global plastic production will reach over 1.1 billion tons by 2050. The success and dominance of plastics starting in the early 20th century has caused widespread environmental problems, due to their slow decomposition rate in natural ecosystems. Most plastic produced has not been reused, or is incapable of reuse, either being captured in landfills or persisting in the environment as plastic pollution and microplastics . Plastic pollution can be found in all
4563-514: Is generally made of heavier, sturdier wood. The earliest use of a bamboo weapon to train with instead of a sword is credited to Kamiizumi Nobutsuna (1508–1572?) of the Shinkage-ryū . The modern shinai , with four slats of bamboo, is generally credited to Nakanishi Chuzo Tsugutate (died 1801) of Nakanishi-ha Ittō-ryū . The shinai was developed in an effort to reduce the number of practitioners being seriously injured during practice, making
4680-446: Is not sold as a pure unadulterated substance, but is instead mixed with various chemicals and other materials, which are collectively known as additives. These are added during the compounding stage and include substances such as stabilizers , plasticizers and dyes , which are intended to improve the lifespan, workability or appearance of the final item. In some cases, this can involve mixing different types of plastic together to form
4797-414: Is performed by simply remelting and reforming used plastic into new items. Additives present risks in recycled products, as they are difficult to remove. When plastic products are recycled, it is highly likely that the additives will be integrated into the new products. Waste plastic, even if it is all of the same polymer type, will contain varying types and amounts of additives. Mixing these together can give
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4914-456: Is sometimes used interchangeably with side-sword. As rapiers became more popular, attempts were made to hybridize the blade, sacrificing the effectiveness found in each unique weapon design. These are still considered side-swords and are sometimes labeled sword rapier or cutting rapier by modern collectors. Side-swords used in conjunction with bucklers became so popular that it caused the term swashbuckler to be coined. This word stems from
5031-482: Is the consistent use of high tin bronze (17–21% tin) which is very hard and breaks if stressed too far, whereas other cultures preferred lower tin bronze (usually 10%), which bends if stressed too far. Although iron swords were made alongside bronze, it was not until the early Han period that iron completely replaced bronze. In the Indian subcontinent , earliest available Bronze age swords of copper were discovered in
5148-448: Is the part of the chain that is on the main path , linking together a large number of repeat units. To customize the properties of a plastic, different molecular groups called side chains hang from this backbone; they are usually hung from the monomers before the monomers themselves are linked together to form the polymer chain. The structure of these side chains influences the properties of the polymer. Plastics are usually classified by
5265-417: Is written with the kanji 竹刀 , meaning "bamboo sword", and is an irregular kanji reading . In kendo , it is most common to use a single shinai , sometimes called ittō (一刀) style. Some kendōka choose to use two shinai . This kendō style is usually called ni-tō ( 二刀 ) , a style that has its roots in the two-sword schools of swordsmanship such as Hyōhō Niten Ichi-ryū . A ni-tō combatant uses
5382-405: The ricasso to improve the grip (a practice that would continue in the rapier ) led to the production of hilts with a guard for the finger. This sword design eventually led to the development of the civilian rapier, but it was not replaced by it, and the side-sword continued to be used during the rapier's lifetime. As it could be used for both cutting and thrusting, the term "cut and thrust sword"
5499-526: The Franks . Wootz steel (which is also known as Damascus steel ) was a unique and highly prized steel developed on the Indian subcontinent as early as the 5th century BC. Its properties were unique due to the special smelting and reworking of the steel creating networks of iron carbides described as a globular cementite in a matrix of pearlite . The use of Damascus steel in swords became extremely popular in
5616-601: The Indian subcontinent made of Damascus steel also found their way into Persia . By the time of Classical Antiquity and the Parthian and Sassanid Empires in Iran, iron swords were common. The Greek xiphos and the Roman gladius are typical examples of the type, measuring some 60 to 70 cm (24 to 28 in). The late Roman Empire introduced the longer spatha (the term for its wielder, spatharius , became
5733-778: The Indus Valley civilization sites in the northwestern regions of South Asia . Swords have been recovered in archaeological findings throughout the Ganges - Jamuna Doab region of Indian subcontinent, consisting of bronze but more commonly copper . Diverse specimens have been discovered in Fatehgarh , where there are several varieties of hilt. These swords have been variously dated to times between 1700 and 1400 BC. Other swords from this period in India have been discovered from Kallur, Raichur . Iron became increasingly common from
5850-491: The International Kendo Federation (FIK) rules are below. Sizes and style of shinai vary. For example, an adult may be able to use a shinai that is too heavy for a younger person, so shinai with different sizes and characteristics are made. Shinai are available in many styles and balances. A shinai should not be confused with a bokutō , which has a much more similar shape and length to
5967-646: The Los Angeles Times reported that the US Food and Drug Administration (FDA) is spending $ 30 million to investigate indications of BPA's link to cancer. Bis(2-ethylhexyl) adipate , present in plastic wrap based on PVC, is also of concern, as are the volatile organic compounds present in new car smell . The EU has a permanent ban on the use of phthalates in toys. In 2009, the US government banned certain types of phthalates commonly used in plastic. Because
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#17327724842176084-588: The Middle Ages , sword technology improved, and the sword became a very advanced weapon. The spatha type remained popular throughout the Migration period and well into the Middle Ages. Vendel Age spathas were decorated with Germanic artwork (not unlike the Germanic bracteates fashioned after Roman coins). The Viking Age saw again a more standardized production, but the basic design remained indebted to
6201-473: The Minamata Convention on Mercury ), which have previously been used in plastic production, are banned in many jurisdictions. However they are still routinely found in some plastic packaging including food packaging. The use of the additive bisphenol A (BPA) in plastic baby bottles is banned in many parts of the world, but is not restricted in some low-income countries. In 2023, plasticosis ,
6318-462: The polymerization of their starting materials ( monomers ); which are almost always petrochemical in nature. Such facilities are normally large and are visually similar to oil refineries , with sprawling pipework running throughout. The large size of these plants allows them to exploit economies of scale . Despite this, plastic production is not particularly monopolized, with about 100 companies accounting for 90% of global production. This includes
6435-431: The shinai for splinters. This is very important, as bamboo splinters can easily cause injury. The saki-gawa should be intact and the tsuru should be tight so that the saki-gawa does not slip off the end of the shinai during use. In addition, the nakayui should be tight enough as not to rotate easily. When not in use, shinai used in kendo practice should be either laid on the floor or leaned vertically against
6552-407: The shinai , or datotsu-bu ( 打突部 ) . Inserted between the ends of the slats, under the saki-gawa , is a plastic plug saki-gomu ( 先ゴム ) , and under the tsuka-gawa there is a small square of metal chigiri ( ちぎり ) , that holds the slats in place. A hand-guard tsuba ( 鍔 ) is then fitted on the tsuka-gawa before it ends and the bamboo slats show. This is held in place by
6669-455: The 11th century. From the 15th century to the 16th century, more than 200,000 swords were exported, reaching a quantitative peak, but these were simple swords made exclusively for mass production, specialized for export and lending to conscripted farmers ( ashigaru ). The khanda is a double-edge straight sword. It is often featured in religious iconography, theatre and art depicting the ancient history of India . Some communities venerate
6786-422: The 13th century BC. Before that the use of swords was less frequent. The iron was not quench-hardened although often containing sufficient carbon, but work-hardened like bronze by hammering. This made them comparable or only slightly better in terms of strength and hardness to bronze swords. They could still bend during use rather than spring back into shape. But the easier production, and the better availability of
6903-459: The 14th-century change from mail to plate armour . It was during the 14th century, with the growing use of more advanced armour, that the hand and a half sword, also known as a " bastard sword ", came into being. It had an extended grip that meant it could be used with either one or two hands. Though these swords did not provide a full two-hand grip they allowed their wielders to hold a shield or parrying dagger in their off hand, or to use it as
7020-509: The 16th and 17th centuries. It was only from the 11th century that Norman swords began to develop the crossguard (quillons). During the Crusades of the 12th to 13th century, this cruciform type of arming sword remained essentially stable, with variations mainly concerning the shape of the pommel . These swords were designed as cutting weapons, although effective points were becoming common to counter improvements in armour, especially
7137-460: The 16th century, the large zweihänder was used by the elite German and Swiss mercenaries known as doppelsöldners . Zweihänder , literally translated, means two-hander. The zweihänder possesses a long blade, as well as a huge guard for protection. It is estimated that some zweihänder swords were over 6 feet (1.8 m) long, with the one ascribed to Frisian warrior Pier Gerlofs Donia being 7 feet (2.13 m) long. The gigantic blade length
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#17327724842177254-684: The 3rd millennium BC in the Middle East, first in arsenic copper , then in tin-bronze. Blades longer than 60 cm (24 in) were rare and not practical until the late Bronze Age because the Young's modulus (stiffness) of bronze is relatively low, and consequently longer blades would bend easily. The development of the sword out of the dagger was gradual; the first weapons that can be classified as swords without any ambiguity are those found in Minoan Crete , dated to about 1700 BC, reaching
7371-647: The 60 to 70 cm range. Robert Drews linked the Naue Type II Swords, which spread from Southern Europe into the Mediterranean, with the Bronze Age collapse . Naue II swords, along with Nordic full-hilted swords, were made with functionality and aesthetics in mind. The hilts of these swords were beautifully crafted and often contained false rivets in order to make the sword more visually appealing. Swords coming from northern Denmark and northern Germany usually contained three or more fake rivets in
7488-638: The Arabic term for a Western European, a " Frank ") was a sword type which used blades manufactured in Western Europe and imported by the Portuguese , or made locally in imitation of European blades. Because of its length the firangi is usually regarded as primarily a cavalry weapon. The sword has been especially associated with the Marathas , who were famed for their cavalry. However, the firangi
7605-494: The EU, over 400 additives are used in high volumes. In a global market analysis, 5,500 additives were found. At a minimum, all plastic contains some polymer stabilizers which permit them to be melt-processed (molded) without suffering polymer degradation . Other additives are optional and can be added as required, with loadings varying significantly between applications. The amount of additives contained in plastics varies depending on
7722-468: The FIK rules, there are regulated weights and lengths for the use of shinai . Shinai are weighed complete with leather fittings, but without tsuba or tsuba-dome . The full length is measured. Maximum diameter of the tsuba is 9cm. Shinai are weighed complete with leather fittings, but without tsuba or tsuba-dome . The full length is measured. Maximum diameter of the tsuba is 9cm. The ancestor of
7839-485: The Greek πλαστικός ( plastikos ), meaning "capable of being shaped or molded ;" in turn, it is from πλαστός ( plastos ) meaning "molded." As a noun , the word most commonly refers to the solid products of petrochemical-derived manufacturing. The noun plasticity refers specifically here to the deformability of the materials used in the manufacture of plastics. Plasticity allows molding , extrusion or compression into
7956-561: The North American Free Trade Agreement or NAFTA region) accounts for 21% of global plastic consumption, closely followed by China (20%) and Western Europe (18%). In North America and Europe, there is high per capita plastic consumption (94 kg and 85 kg/capita/year, respectively). In China, there is lower per capita consumption (58 kg/capita/year), but high consumption nationally because of its large population. The largest application for plastics
8073-516: The United States Environmental Protection Agency (US EPA) revealed that out of 3,377 chemicals potentially associated with plastic packaging and 906 likely associated with it, 68 were ranked by ECHA as "highest for human health hazards" and 68 as "highest for environmental hazards". As additives change the properties of plastics they have to be considered during recycling. Presently, almost all recycling
8190-486: The additives' function. For example, additives in polyvinyl chloride (PVC) can constitute up to 80% of the total volume. Pure unadulterated plastic (barefoot resin) is never sold, even by the primary producers. Additives may be weakly bound to the polymers or react in the polymer matrix. Although additives are blended into plastic they remain chemically distinct from it, and can gradually leach back out during normal use, when in landfills, or following improper disposal in
8307-534: The birth of the plastic industry in the 1950s, global production has increased enormously, reaching 400 million tonnes a year in 2021; this is up from 381 million metric tonnes in 2015 (excluding additives). From the 1950s, rapid growth occurred in the use of plastics for packaging, in building and construction, and in other sectors. If global trends on plastic demand continue, it is estimated that by 2050 annual global plastic production will exceed 1.1 billion tonnes annually. Plastics are produced in chemical plants by
8424-690: The chemical profile of the final products. For example, products containing brominated flame retardants have been incorporated into new plastic products. Flame retardants are a group of chemicals used in electronic and electrical equipment, textiles, furniture and construction materials which should not be present in food packaging or child care products. A recent study found brominated dioxins as unintentional contaminants in toys made from recycled plastic electronic waste that contained brominated flame retardants. Brominated dioxins have been found to exhibit toxicity similar to that of chlorinated dioxins. They can have negative developmental effects and negative effects on
8541-448: The chemical structure of most plastics renders them durable, they are resistant to many natural degradation processes. Much of this material may persist for centuries or longer, given the demonstrated persistence of structurally similar natural materials such as amber . There are differing estimates of how much plastic waste has been produced in the last century. By one estimate, one billion tons of plastic waste have been discarded since
8658-802: The chemical structure of the polymer's backbone and side chains. Important groups classified in this way include the acrylics , polyesters , silicones , polyurethanes , and halogenated plastics . Plastics can be classified by the chemical process used in their synthesis, such as condensation , polyaddition , and cross-linking . They can also be classified by their physical properties, including hardness , density , tensile strength , thermal resistance , and glass transition temperature . Plastics can additionally be classified by their resistance and reactions to various substances and processes, such as exposure to organic solvents, oxidation , and ionizing radiation . Other classifications of plastics are based on qualities relevant to manufacturing or product design for
8775-617: The classical arming sword with crossguard. The word sword continues the Old English , sweord . The use of a sword is known as swordsmanship or, in a modern context, as fencing . In the early modern period , western sword design diverged into two forms, the thrusting swords and the sabres. Thrusting swords such as the rapier and eventually the smallsword were designed to impale their targets quickly and inflict deep stab wounds. Their long and straight yet light and well balanced design made them highly maneuverable and deadly in
8892-452: The commodity plastics, with many having exceptional properties. Engineering plastics are more robust and are used to make products such as vehicle parts, building and construction materials, and some machine parts. In some cases they are polymer blends formed by mixing different plastics together (ABS, HIPS etc.). Engineering plastics can replace metals in vehicles, lowering their weight and improving fuel efficiency by 6–8%. Roughly 50% of
9009-513: The developing world, the applications of plastic may differ; 42% of India's consumption is used in packaging. In the medical field, polymer implants and other medical devices are derived at least partially from plastic. Worldwide, about 50 kg of plastic is produced annually per person, with production doubling every ten years. The world's first fully synthetic plastic was Bakelite , invented in New York in 1907, by Leo Baekeland , who coined
9126-666: The effects of such leachates , the EU has restricted the use of DEHP (di-2-ethylhexyl phthalate) and other phthalates in some applications, and the US has limited the use of DEHP, DPB , BBP , DINP , DIDP , and DnOP in children's toys and child-care articles through the Consumer Product Safety Improvement Act . Some compounds leaching from polystyrene food containers have been proposed to interfere with hormone functions and are suspected human carcinogens (cancer-causing substances). Other chemicals of potential concern include alkylphenols . While
9243-401: The environment. Additives may also degrade to form other toxic molecules. Plastic fragmentation into microplastics and nanoplastics can allow chemical additives to move in the environment far from the point of use. Once released, some additives and derivatives may persist in the environment and bioaccumulate in organisms. They can have adverse effects on human health and biota. A recent review by
9360-407: The finite limits of fossil fuel reserves and to rising levels of greenhouse gases caused primarily by the burning of those fuels, the development of bioplastics is a growing field. Global production capacity for bio-based plastics is estimated at 327,000 tonnes per year. In contrast, global production of polyethylene (PE) and polypropylene (PP), the world's leading petrochemical-derived polyolefins,
9477-529: The gaps between plates of armour. The grip was sometimes wrapped in wire or coarse animal hide to provide a better grip and to make it harder to knock a sword out of the user's hand. A number of manuscripts covering longsword combat and techniques dating from the 13th–16th centuries exist in German, Italian, and English, providing extensive information on longsword combatives as used throughout this period. Many of these are now readily available online. In
9594-635: The hilt. Sword production in China is attested from the Bronze Age Shang dynasty . The technology for bronze swords reached its high point during the Warring States period and Qin dynasty. Amongst the Warring States period swords, some unique technologies were used, such as casting high tin edges over softer, lower tin cores, or the application of diamond shaped patterns on the blade (see sword of Goujian ). Also unique for Chinese bronzes
9711-568: The host resin. Masterbatch granules can be mixed with cheaper bulk polymer and will release their additives during processing to give a homogeneous final product. This can be cheaper than working with a fully compounded material and is particularly common for the introduction of color. Companies that produce finished goods are known as converters (sometimes processors). The vast majority of plastics produced worldwide are thermosoftening and must be heated until molten in order to be molded. Various sorts of extrusion equipment exist which can then form
9828-480: The knife or dagger. The sword became differentiated from the dagger during the Bronze Age ( c. 3000 BC), when copper and bronze weapons were produced with long leaf-shaped blades and with hilts consisting of an extension of the blade in handle form. A knife is unlike a dagger in that a knife has only one cutting surface, while a dagger has two cutting surfaces. Construction of longer blades became possible during
9945-486: The late Renaissance, with duels being a preferred way to honourably settle disputes. The side-sword was a type of war sword used by infantry during the Renaissance of Europe . This sword was a direct descendant of the knightly sword . Quite popular between the 16th and 17th centuries, they were ideal for handling the mix of armoured and unarmoured opponents of that time. A new technique of placing one's finger on
10062-535: The later part of the Western Zhou dynasty , but iron and steel swords were not widely used until the 3rd century BC Han dynasty . The Chinese dao (刀 pinyin dāo) is single-edged, sometimes translated as sabre or broadsword , and the jian (劍 or 剑 pinyin jiàn) is double-edged. The zhanmadao (literally "horse chopping sword") is an extremely long, anti-cavalry sword from the Song dynasty era. During
10179-604: The majority of products, it is necessary to melt the plastic in order to mix-in the additives. This involves heating it to anywhere between 150–320 °C (300–610 °F). Molten plastic is viscous and exhibits laminar flow , leading to poor mixing. Compounding is therefore done using extrusion equipment, which is able to supply the necessary heat and mixing to give a properly dispersed product. The concentrations of most additives are usually quite low, however high levels can be added to create Masterbatch products. The additives in these are concentrated but still properly dispersed in
10296-413: The modern kendo shinai is the fukuro-shinai ( 袋竹刀 ) , which is still in use in koryū kenjutsu . This is a length of bamboo, split multiple times on one end, and covered by a leather sleeve. This explains the name fukuro , which means bag, sack or pouch. Sometimes the older and rarer kanji tō (韜) is used, but has the same meaning as fukuro. Some schools cover the entire bamboo in the sleeve and add
10413-515: The most versatile for close combat, but it came to decline in military use as technology, such as the crossbow and firearms changed warfare. However, it maintained a key role in civilian self-defence . The earliest evidence of curved swords, or scimitars (and other regional variants as the Arabian saif , the Persian shamshir and the Turkic kilij ) is from the 9th century, when it
10530-657: The name of akrafena . They are still used today in ceremonies, such as the Odwira festival . As steel technology improved, single-edged weapons became popular throughout Asia. Derived from the Chinese jian or dao , the Korean hwandudaedo are known from the early medieval Three Kingdoms . Production of the Japanese tachi , a precursor to the katana , is recorded from c. AD 900 (see Japanese sword ). Japan
10647-450: The nervous system and interfere with mechanisms of the endocrine system. Many of the controversies associated with plastics actually relate to their additives, as some compounds can be persistent, bioaccumulating and potentially harmful. The now banned flame retardants OctaBDE and PentaBDE are an example of this, while the health effects of phthalates are an ongoing area of public concern. Additives can also be problematic if waste
10764-574: The new fighting style of the side-sword and buckler which was filled with much "swashing and making a noise on the buckler". Within the Ottoman Empire , the use of a curved sabre called the yatagan started in the mid-16th century. It would become the weapon of choice for many in Turkey and the Balkans . The sword in this time period was the most personal weapon, the most prestigious, and
10881-709: The plastic be exposed at the surface, whereas anaerobic degradation would be effective in landfill or composting systems. Some companies produce biodegradable additives to enhance biodegradation. Although starch powder can be added as a filler to allow some plastics to degrade more easily, such treatment does not lead to complete breakdown. Some researchers have genetically engineered bacteria to synthesize completely biodegradable plastics, such as polyhydroxy butyrate (PHB); however, these were still relatively costly as of 2021. While most plastics are produced from petrochemicals, bioplastics are made substantially from renewable plant materials like cellulose and starch. Due both to
10998-571: The plastic into almost any shape. For thermosetting materials the process is slightly different, as the plastics are liquid to begin with and but must be cured to give solid products, but much of the equipment is broadly similar. The most commonly produced plastic consumer products include packaging made from LDPE (e.g. bags, containers, food packaging film), containers made from HDPE (e.g. milk bottles, shampoo bottles, ice cream tubs), and PET (e.g. bottles for water and other drinks). Together these products account for around 36% of plastics use in
11115-464: The preferred choice for the mass production everyday objects. Their biggest single application is in packaging, with some 146 million tonnes being used this way in 2015, equivalent to 36% of global production. Due to their dominance; many of the properties and problems commonly associated with plastics, such as pollution stemming from their poor biodegradability , are ultimately attributable to commodity plastics. A huge number of plastics exist beyond
11232-413: The properties of plastics to better suit their intended applications. Additives are therefore one of the reasons why plastic is used so widely. Plastics are composed of chains of polymers. Many different chemicals are used as plastic additives. A randomly chosen plastic product generally contains around 20 additives. The identities and concentrations of additives are generally not listed on products. In
11349-429: The raw material for the first time permitted the equipping of entire armies with metal weapons, though Bronze Age Egyptian armies were sometimes fully equipped with bronze weapons. Ancient swords are often found at burial sites. The sword was often placed on the right side of the corpse. Many times the sword was kept over the corpse. In many late Iron Age graves, the sword and the scabbard were bent at 180 degrees. It
11466-432: The relative innocuous nature of bamboo vs razor-sharp steel, the impacted area is less damaged and may experience only bruising, rather than life-threatening deep cuts or puncture wounds, even with strong and forceful strikes. A shinai must be properly taken care of or it can pose a danger to both the user and the people around it. Shinai should be inspected for splinters and breaks before and after use, and maintained in
11583-438: The rise of the samurai caste include the tsurugi (straight double-edged blade) and chokutō (straight one-edged blade). Japanese swordmaking reached the height of its development in the 15th and 16th centuries, when samurai increasingly found a need for a sword to use in closer quarters, leading to the creation of the modern katana . High quality Japanese swords have been exported to neighboring Asian countries since before
11700-511: The sabre's long curved blade and slightly forward weight balance gave it a deadly character all its own on the battlefield. Most sabres also had sharp points and double-edged blades, making them capable of piercing soldier after soldier in a cavalry charge. Sabres continued to see battlefield use until the early 20th century. The US Navy M1917 Cutlass used in World War I was kept in their armory well into World War II and many Marines were issued
11817-451: The spatha. Around the 10th century, the use of properly quenched hardened and tempered steel started to become much more common than in previous periods. The Frankish 'Ulfberht' blades (the name of the maker inlaid in the blade) were of particularly consistent high quality. Charles the Bald tried to prohibit the export of these swords, as they were used by Vikings in raids against
11934-601: The sword developed in the Bronze Age , evolving from the dagger; the earliest specimens date to about 1600 BC. The later Iron Age sword remained fairly short and without a crossguard. The spatha , as it developed in the Late Roman army , became the predecessor of the European sword of the Middle Ages, at first adopted as the Migration Period sword , and only in the High Middle Ages , developed into
12051-528: The term "plastics". Dozens of different types of plastics are produced today, such as polyethylene , which is widely used in product packaging , and polyvinyl chloride (PVC), used in construction and pipes because of its strength and durability. Many chemists have contributed to the materials science of plastics, including Nobel laureate Hermann Staudinger , who has been called "the father of polymer chemistry ," and Herman Mark , known as "the father of polymer physics ". The word plastic derives from
12168-762: The thermosetting process, an irreversible chemical reaction occurs. The vulcanization of rubber is an example of this process. Before heating in the presence of sulfur, natural rubber ( polyisoprene ) is a sticky, slightly runny material; after vulcanization, the product is dry and rigid. Around 70% of global production is concentrated in six major polymer types, the so-called commodity plastics . Unlike most other plastics these can often be identified by their resin identification code (RIC): Polyurethanes (PUR) and PP&A fibers are often also included as major commodity classes, although they usually lack RICs, as they are chemically quite diverse groups. These materials are inexpensive, versatile and easy to work with, making them
12285-444: The volume of modern cars is made of plastic, but this only accounts for 12–17% of the vehicle weight. High-performance plastics are usually expensive, with their use limited to specialized applications which make use of their superior properties. Many plastics are completely amorphous (without a highly ordered molecular structure), including thermosets, polystyrene, and methyl methacrylate (PMMA). Crystalline plastics exhibit
12402-581: The volume of plastics production are driven by user demand, the price of fossil fuel feedstocks, and investments made in the petrochemical industry. For example, since 2010 over US$ 200 billion has been invested in the United States in new plastic and chemical plants, stimulated by the low cost of raw materials. In the European Union (EU), too, heavy investments have been made in the plastics industry, which employs over 1.6 million people with
12519-520: The weapon as a symbol of Shiva . It is a common weapon in the martial arts in the Indian subcontinent . The khanda often appears in Hindu , Buddhist and Sikh scriptures and art. In Sri Lanka , a unique wind furnace was used to produce the high-quality steel. This gave the blade a very hard cutting edge and beautiful patterns. For these reasons it became a very popular trading material. The firangi ( / f ə ˈ r ɪ ŋ ɡ iː / , derived from
12636-459: The weapon has been lost somewhat as the name akinaka has been used to refer to whichever form of sword the Persian army favoured at the time. It is widely believed that the original akinaka was a 35 to 45 cm (14 to 18 inch) double-edged sword. The design was not uniform and in fact identification is made more on the nature of the scabbard than the weapon itself; the scabbard usually has
12753-497: The world's major water bodies , for example, creating garbage patches in all of the world's oceans and contaminating terrestrial ecosystems. Of all the plastic discarded so far, some 14% has been incinerated and less than 10% has been recycled. In developed economies, about a third of plastic is used in packaging and roughly the same in buildings in applications such as piping , plumbing or vinyl siding . Other uses include automobiles (up to 20% plastic ), furniture, and toys. In
12870-726: The world. Most of them (e.g. disposable cups, plates, cutlery, takeaway containers, carrier bags) are used for only a short period, many for less than a day. The use of plastics in building and construction, textiles, transportation and electrical equipment also accounts for a substantial share of the plastics market. Plastic items used for such purposes generally have longer life spans. They may be in use for periods ranging from around five years (e.g. textiles and electrical equipment) to more than 20 years (e.g. construction materials, industrial machinery). Plastic consumption differs among countries and communities, with some form of plastic having made its way into most people's lives. North America (i.e.
12987-481: Was also widely used by Sikhs and Rajputs . The talwar ( Hindi : तलवार ) is a type of curved sword from India and other countries of the Indian subcontinent , it was adopted by communities such as Rajputs, Sikhs and Marathas, who favored the sword as their main weapon. It became more widespread in the medieval era. The urumi ( Tamil : சுருள் பட்டாக்கத்தி surul pattai , lit. curling blade; Sinhala : එතුණු කඩුව ethunu kaduwa ; Hindi : aara )
13104-644: Was estimated at over 150 million tonnes in 2015. The plastic industry includes the global production, compounding , conversion and sale of plastic products. Although the Middle East and Russia produce most of the required petrochemical raw materials, the production of plastic is concentrated in the global East and West. The plastic industry comprises a huge number of companies and can be divided into several sectors: Between 1950 and 2017, 9.2 billion tonnes of plastic are estimated to have been made, with more than half this having been produced since 2004. Since
13221-583: Was famous for the swords it forged in the early 13th century for the class of warrior-nobility known as the Samurai . Western historians have said that Japanese katana were among the finest cutting weapons in world military history. The types of swords used by the Samurai included the ōdachi (extra long field sword), tachi (long cavalry sword), katana (long sword), and wakizashi (shorter companion sword for katana ). Japanese swords that pre-date
13338-469: Was known as killing the sword. Thus they might have considered swords as the most potent and powerful object. High-carbon steel for swords, which would later appear as Damascus steel , was likely introduced in India around the mid-1st millennium BC. The Periplus of the Erythraean Sea mentions swords of Indian iron and steel being exported from ancient India to ancient Greece . Blades from
13455-443: Was perfectly designed for manipulating and pushing away enemy polearms , which were major weapons around this time, in both Germany and Eastern Europe. Doppelsöldners also used katzbalgers , which means 'cat-gutter'. The katzbalger's S-shaped guard and 2-foot-long (0.61 m) blade made it perfect for bringing in when the fighting became too close to use a zweihänder . Civilian use of swords became increasingly common during
13572-524: Was the lengthening of the grip, allowing two-handed use, and a longer blade. By 1400, this type of sword, at the time called langes Schwert (longsword) or spadone , was common, and a number of 15th- and 16th-century Fechtbücher offering instructions on their use survive. Another variant was the specialized armour-piercing swords of the estoc type. The longsword became popular due to its extreme reach and its cutting and thrusting abilities. The estoc became popular because of its ability to thrust into
13689-480: Was used among soldiers in the Khurasan region of Persia . The takoba is a type of broadsword originating in the western Sahel , descended from various Byzantine and Islamic swords. It has a straight double-edged blade measuring about one meter in length, usually imported from Europe. Abyssinian swords related to the Persian shamshir are known as shotel . The Asante people adopted swords under
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