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88-446: A winter guard generally consists of performing members under the direction of instructional staff. The staff of a winter guard team are drawn from many different specialties, which sometimes overlap: there are equipment instructors (sometimes one for the unit, sometimes broken out into the individual sections), dance instructors, and drill instructors. The equipment instructors create the choreography performed with equipment and teach it to

176-480: A carrier or by blending in extruders. Cyclic olefin copolymers are prepared by copolymerization of ethene and cycloolefins (usually norbornene ) produced by using metallocene catalysts. The resulting polymers are amorphous polymers and particularly transparent and heat resistant. The basic compounds used as polar comonomers are vinyl alcohol ( Ethenol , an unsaturated alcohol), acrylic acid ( propenoic acid , an unsaturated acid) and esters containing one of

264-431: A coherent whole.” Choreography consisting of ordinary motor activities, social dances, commonplace movements or gestures, or athletic movements may lack a sufficient amount of authorship to qualify for copyright protection. A recent lawsuit was brought by professional dancer and choreographer Kyle Hanagami, who sued Epic Games, alleging that the video game developer copied a portion of Hanagami’s copyrighted dance moves in

352-580: A density range of 0.880–0.915 g/cm . VLDPE is a substantially linear polymer with high levels of short-chain branches, commonly made by copolymerization of ethylene with short-chain alpha-olefins (for example, 1-butene, 1-hexene and 1-octene). VLDPE is most commonly produced using metallocene catalysts due to the greater co-monomer incorporation exhibited by these catalysts. VLDPEs are used for hose and tubing, ice and frozen food bags, food packaging and stretch wrap as well as impact modifiers when blended with other polymers. Much research activity has focused on

440-577: A feeder school of that high school. There are many colleges and universities that sponsor their own winter guards as well, but these guards typically compete as Independent guards. Scholastic guards vary greatly in their ability and resources because they are more dependent on support from sources other than the members themselves, such as their school's band and school funding. In the Scholastic division, there are three classes: Scholastic A , Scholastic Open , and Scholastic World . More divisions may exist at

528-458: A few that could use plastic as their only carbon source. Not only could the bacteria from the guts of the Plodia interpunctella moth larvae metabolize polyethylene, they degraded it significantly, dropping its tensile strength by 50%, its mass by 10% and the molecular weights of its polymeric chains by 13%. The caterpillar of Galleria mellonella is claimed to consume polyethylene. The caterpillar

616-401: A higher class, but they can only move down a class after a period of inactivity or after a WGI review. For every competition, any team which achieves a score higher than a predetermined threshold is automatically moved up, or "bumped", to the class above its current position, even mid-season. The Scholastic division is made up of guards that have members that all attend the same high school or

704-410: A material called polyethylene , making the rifle sturdier and harder to break. The material can also be colored so that different teams can use different colored rifles. Sometimes, though, the material can warp after several bad drops, which can lead to a bad spin while the rifle is in the air. Some say that, after a prolonged period of regular use, a plastic rifle will tend to smell like sweat because of

792-501: A mixture of ethylene and benzaldehyde they again produced a white, waxy material. Because the reaction had been initiated by trace oxygen contamination in their apparatus, the experiment was difficult to reproduce at first. It was not until 1935 that another ICI chemist, Michael Perrin , developed this accident into a reproducible high-pressure synthesis for polyethylene that became the basis for industrial low-density polyethylene ( LDPE ) production beginning in 1939. Because polyethylene

880-552: A multi-use plastic. However, polyethylene's chemical resilience also makes it a long-lived and decomposition-resistant pollutant when disposed of improperly. Being a hydrocarbon , polyethylene is colorless to opaque (without impurities or colorants) and combustible. Polyethylene was first synthesized by the German chemist Hans von Pechmann , who prepared it by accident in 1898 while investigating diazomethane . When his colleagues Eugen Bamberger and Friedrich Tschirner characterized

968-412: A relatively narrow molecular weight distribution , exceptionally high toughness, excellent optical properties and a uniform comonomer content. Because of the narrow molecular weight distribution it behaves less pseudoplastic (especially under larger shear rates). Metallocene polyethylene has a low proportion of low molecular weight (extractable) components and a low welding and sealing temperature. Thus, it

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1056-445: A running commentary on a tape recorder or digital recorder. The judges record the score on a designated sheet to be reviewed by the individual guard instructor(s). After every one in a class has competed and their scores have been tallied, if the instructor(s) so choose they may meet with all the judges to discuss in depth why they received the score they did, ways to improve, what they are doing right etc. The goal of all parties involved,

1144-487: Is ethylene-vinyl acetate copolymer , or EVA, widely used in athletic-shoe sole foams) and a variety of acrylates . Applications of acrylic copolymer include packaging and sporting goods, and superplasticizer , used in cement production. The particular material properties of "polyethylene" depend on its molecular structure. Molecular weight and crystallinity are the most significant factors; crystallinity in turn depends on molecular weight and degree of branching. The less

1232-410: Is a good electrical insulator . It offers good electrical treeing resistance; however, it becomes easily electrostatically charged (which can be reduced by additions of graphite , carbon black or antistatic agents ). When pure, the dielectric constant is in the range 2.2 to 2.4 depending on the density and the loss tangent is very low, making it a good dielectric for building capacitors . For

1320-651: Is able to digest polyethylene due to a combination of its gut microbiota and its saliva containing enzymes that oxidise and depolymerise the plastic. When exposed to ambient solar radiation the plastic produces trace amounts of two greenhouse gases , methane and ethylene . The plastic type which releases gases at the highest rate is low-density polyethylene (LDPE). Due to its low density it breaks down more easily over time, leading to higher surface areas. When incubated in air, LDPE emits gases at rates ~2 times and ~76 times higher in comparison to incubation in water for methane and ethylene, respectively. However, based on

1408-546: Is composed of winter guard teams that do not associate themselves with a school (the exception being university teams). Additionally, these kinds of guards can be much more selective of their members, choosing to be gender-specific or to only have certain numbers of members. In the Independent division, much like the Scholastic division, there are the three classes: Independent A , Independent Open and Independent World . The breakdown of skill level and placement mirrors that of

1496-462: Is defined by a density of greater or equal to 0.941 g/cm . HDPE has a low degree of branching. The mostly linear molecules pack together well, so intermolecular forces are stronger than in highly branched polymers. HDPE can be produced by chromium /silica catalysts, Ziegler–Natta catalysts or metallocene catalysts; by choosing catalysts and reaction conditions, the small amount of branching that does occur can be controlled. These catalysts prefer

1584-538: Is defined by a density range of 0.910–0.940 g/cm . LDPE has a high degree of short- and long-chain branching, which means that the chains do not pack into the crystal structure as well. It has, therefore, less strong intermolecular forces as the instantaneous-dipole induced-dipole attraction is less. This results in a lower tensile strength and increased ductility . LDPE is created by free-radical polymerization . The high degree of branching with long chains gives molten LDPE unique and desirable flow properties. LDPE

1672-551: Is defined by a density range of 0.915–0.925 g/cm . LLDPE is a substantially linear polymer with significant numbers of short branches, commonly made by copolymerization of ethylene with short-chain alpha-olefins (for example, 1-butene , 1-hexene , and 1-octene ). LLDPE has higher tensile strength than LDPE, and it exhibits higher impact and puncture resistance than LDPE. Lower-thickness (gauge) films can be blown, compared with LDPE, with better environmental stress cracking resistance, but they are not as easy to process. LLDPE

1760-429: Is defined by a density range of 0.926–0.940 g/cm . MDPE can be produced by chromium/silica catalysts, Ziegler–Natta catalysts, or metallocene catalysts. MDPE has good shock and drop resistance properties. It also is less notch-sensitive than HDPE; stress-cracking resistance is better than HDPE. MDPE is typically used in gas pipes and fittings, sacks, shrink film, packaging film, carrier bags, and screw closures. LLDPE

1848-454: Is more commonly used. Other metal sabres are decorated with intricate engravings or etchings along the blade, which most often carries a much higher price. Sabres have two main parts: the blade and the hilt. The blade has a pointed but dull end, and the length of the blade is dull as well. Like the wooden rifles, electrical tape can be used to improve the grip on the blade of the sabre, which is useful in choreography involving catching or holding

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1936-416: Is much less than for producing hydrogen by electrolysis. Several experiments have been conducted aimed at discovering enzyme or organisms that will degrade polyethylene. Several plastics - polyesters, polycarbonates, polyamides - degrade either by hydrolysis or air oxidation. In some cases the degradation is increased by bacteria or various enzyme cocktails. The situation is very different polymers where

2024-766: Is particularly suitable for the food industry. Polyethylene with multimodal molecular weight distribution consists of several polymer fractions, which are homogeneously mixed. Such polyethylene types offer extremely high stiffness, toughness, strength, stress crack resistance and an increased crack propagation resistance. They consist of equal proportions higher and lower molecular polymer fractions. The lower molecular weight units crystallize easier and relax faster. The higher molecular weight fractions form linking molecules between crystallites, thereby increasing toughness and stress crack resistance. Polyethylene with multimodal molecular weight distribution can be prepared either in two-stage reactors, by catalysts with two active centers on

2112-435: Is performing. In competition settings, each winter guard team is allotted a set amount of time to set up staging (including a vinyl floor if the guard is using one, and any props associated with the performance), place all equipment, perform the show, and remove staging, props, and equipment. Setup and tear-down typically run two minutes each, and performances run around five minutes. Judges impose penalties on teams that run past

2200-1063: Is the Mid-York Colorguard Circuit , established in 1965. Another is the AIA circuit, or Atlantic Indoor Association circuit in which teams across Virginia, Washington D.C., and North Carolina participate. These circuits are loosely organized and may not be formally affiliated with WGI. In many cases the circuits predate WGI by a number of years. For example, the Midwest Color Guard Circuit celebrated their 50th anniversary season in 2007. They may also have different competitive structures with additional classes to those in WGI. Circuit classes often will include beginner or novice guards such as Cadet , Novice , B , Regional AAA , Regional AA , Regional A , Regional Open , and Senior . Circuits generally score using WGI standards and judges whether they are formally affiliated with WGI or not. In addition,

2288-430: Is the art or practice of designing sequences of movements of physical bodies (or their depictions) in which motion or form or both are specified. Choreography may also refer to the design itself. A choreographer is one who creates choreographies by practising the art of choreography, a process known as choreographing . It most commonly refers to dance choreography . In dance, choreography. may also refer to

2376-807: Is the longest-running choreography competition in the world (started c.  1982 ), organised by the Ballett Gesellschaft Hannover e.V. It took place online during the COVID-19 pandemic in 2020 and 2021, returning to the stage at the Theater am Aegi in 2022. Gregor Zöllig, head choreographer of dance at the Staatstheater Braunschweig was appointed artistic director of the competition in 2020. The main conditions of entry are that entrants must be under 40 years of age, and professionally trained. The competition has been run in collaboration with

2464-423: Is to have the performers, staff, and the programs grow and learn. Three primary types of equipment are used in winter guard: flags, rifles, and sabres. Flags may appear in a variety of sizes and formats. Such equipment is used in shows to demonstrate a team's technical ability. Rubber tape, such as electrical tape, is often used to cover the equipment and give it a uniform appearance and protect it from damage during

2552-448: Is used for both rigid containers and plastic film applications such as plastic bags and film wrap. The radical polymerization process used to make LDPE does not include a catalyst that "supervises" the radical sites on the growing PE chains. (In HDPE synthesis, the radical sites are at the ends of the PE chains, because the catalyst stabilizes their formation at the ends.) Secondary radicals (in

2640-451: Is used in a diverse range of applications. These include can- and bottle -handling machine parts, moving parts on weaving machines, bearings, gears, artificial joints, edge protection on ice rinks, steel cable replacements on ships, and butchers' chopping boards. It is commonly used for the construction of articular portions of implants used for hip and knee replacements . As fiber , it competes with aramid in bulletproof vests . HDPE

2728-450: Is used in packaging, particularly film for bags and sheets. Lower thickness may be used compared to LDPE. It is used for cable coverings, toys, lids, buckets, containers, and pipe. While other applications are available, LLDPE is used predominantly in film applications due to its toughness, flexibility, and relative transparency. Product examples range from agricultural films, Saran wrap, and bubble wrap to multilayer and composite films. LDPE

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2816-537: Is used to design dances that are intended to be performed as concert dance . The art of choreography involves the specification of human movement and form in terms of space, shape, time and energy, typically within an emotional or non-literal context. Movement language is taken from the dance techniques of ballet , contemporary dance , jazz dance , hip hop dance , folk dance , techno , K-pop , religious dance, pedestrian movement, or combinations of these. The word choreography literally means "dance-writing" from

2904-501: Is usually produced from petrochemical sources, but also is generated by dehydration of ethanol. Polymerization of ethylene to polyethylene is described by the following chemical equation : Ethylene is a stable molecule that polymerizes only upon contact with catalysts. The conversion is highly exothermic . Coordination polymerization is the most pervasive technology, which means that metal chlorides or metal oxides are used. The most common catalysts consist of titanium(III) chloride ,

2992-595: The Tanja Liedtke Foundation since her death in 2008, and from 2021 a new production prize has been awarded by the foundation, to complement the five other production awards. The 2021 and 2022 awards were presented by Marco Goecke , then director of ballet at the Staatstheater Hannover . There are a number of other international choreography competitions, mostly focused on modern dance. These include: The International Online Dance Competition (IODC)

3080-430: The design itself, which is sometimes expressed by means of dance notation . Dance choreography is sometimes called dance composition . Aspects of dance choreography include the compositional use of organic unity , rhythmic or non-rhythmic articulation, theme and variation, and repetition. The choreographic process may employ improvisation for the purpose of developing innovative movement ideas. In general, choreography

3168-401: The metallocenes , were reported in 1976 by Walter Kaminsky and Hansjörg Sinn . The Ziegler- and metallocene-based catalysts families have proven to be very flexible at copolymerizing ethylene with other olefins and have become the basis for the wide range of polyethylene resins available today, including very-low-density polyethylene and linear low-density polyethylene . Such resins, in

3256-1247: The 19th century, and romantic ballet choreographers included Carlo Blasis , August Bournonville , Jules Perrot and Marius Petipa . Modern dance brought a new, more naturalistic style of choreography, including by Russian choreographer Michel Fokine (1880-1942) and Isadora Duncan (1878-1927), and since then styles have varied between realistic representation and abstraction. Merce Cunningham , George Balanchine , and Sir Frederick Ashton were all influential choreographers of classical or abstract dance, but Balanchine and Ashton, along with Martha Graham , Leonide Massine , Jerome Robbins and others also created representational works. Isadora Duncan loved natural movement and improvisation . The work of Alvin Ailey (1931-1989), an African-American dancer, choreographer, and activist, spanned many styles of dance, including ballet, jazz , modern dance, and theatre. Dances are designed by applying one or both of these fundamental choreographic methods: Several underlying techniques are commonly used in choreography for two or more dancers: Movements may be characterized by dynamics, such as fast, slow, hard, soft, long, and short. Today,

3344-727: The Arts" is frequently associated with WGI. Winter guard is described by saying "it brings music to life through performance in a competitive format." Because not every color guard has the same skill level, population, or resources available, WGI uses a class division system to help remedy this. There are two divisions, Scholastic and Independent . These divisions include the classes (in descending order) Independent: Independent World Class, Independent Open Class, Independent A Class. Scholastic: Scholastic World, Scholastic Open, Scholastic National A Class, Scholastic Regional A, AA, and AAA. Novice Class and Cadet Class. Guard teams can be chosen to move to

3432-568: The Greek words "χορεία" (circular dance, see choreia ) and "γραφή" (writing). It first appeared in the American English dictionary in the 1950s, and "choreographer" was first used as a credit for George Balanchine in the Broadway show On Your Toes in 1936. Before this, stage credits and movie credits used phrases such as "ensembles staged by", "dances staged by", or simply "dances by" to denote

3520-571: The Phillips catalyst. The Phillips catalyst is less expensive and easier to work with, however, and both methods are heavily used industrially. By the end of the 1950s both the Phillips- and Ziegler -type catalysts were being used for high-density polyethylene (HDPE) production. In the 1970s, the Ziegler system was improved by the incorporation of magnesium chloride . Catalytic systems based on soluble catalysts,

3608-554: The Scholastic division. There are age restrictions in the Independent A and Open classes. A member can perform with an Independent A class group if they are 22 or younger as of March 31 of that year. A member can perform with an Independent Open class group if they are 23 or younger as of March 31 of that year. Although the goal of many winter guards is to compete in the WGI World Championships, most guard competitions take place in regional winter guard circuits. One such circuit

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3696-407: The activity does not exist. " On Guard: A Story of American Youth " is 2023 documentary film directed by Allen Otto and executive produced by Jim Czarnecki. The film follows the journey of an all-female color guard team at Bel Air High School whose goal is to qualify for the 2020 WGI World Championships , which were ultimately canceled due to the COVID-19 pandemic , with a performance dedicated to

3784-470: The activity has started. There are judges who judge separate elements of a show – such as general effect, movement, equipment, and penalty points – and score the groups accordingly. Because this activity not only exists in the United States but all around the world, major competitions worldwide are sanctioned and managed by Winter Guard International. This is the governing organization that makes and changes

3872-520: The activity. Arguably, the foundational equipment in color guard or winter guard is the flag. While winter guard flags take many different sizes and shapes, a standard size is a six-foot metal, fiberglass, or plastic pole with a 36 inch tall by 54 in wide silk, often including custom sewn or digitally printed designs. Flags with shorter poles and larger silks, called "swing flags", are popular for creating large visual impact as performers can manipulate two flags at once. These flags are often incorporated into

3960-484: The allotted time. Unlike traditional color guard teams, which perform outdoors on a football field or parade route accompanied by a marching band or drum corps , winter guard teams perform indoors to recorded music. In competitions, winter guard teams are judged in the areas of talent, precision, creativity, and horizontal orchestration (how all the elements create the larger picture/effect). Performances incorporate equipment, props, and dance moves. Judges must keep

4048-406: The artistic element of the performance, even though they are not practical for tossing or spinning, due to the weight and length of the silk. Other flags may range from 5 feet to 7 feet depending upon the intended effect of the piece of equipment. Longer flags are not practical to spin or toss but generally serve as holders for large pieces of material. Designed visually similarly to actual rifles ,

4136-414: The backbone consists solely of C-C bonds. These polymers include polyethylene, but also polypropylene, polystyrene and acrylates. At best, these polymers degrade very slowly, but these experiments are difficult because yields and rates are very slow. Further confusing the situation, even preliminary successes are greeted with enthusiasm by the popular press. Some technical challenges in this area include

4224-410: The choreographer. In Renaissance Italy , dance masters created movements for social dances which were taught, while staged ballets were created in a similar way. In 16th century France, French court dances were developed in an artistic pattern. In the 17th and 18th centuries, social dance became more separated from theatrical dance performances. During this time the word choreography was applied to

4312-474: The commercial production of polyethylene began with the development of catalysts that promoted the polymerization at mild temperatures and pressures. The first of these was a catalyst based on chromium trioxide discovered in 1951 by Robert Banks and J. Paul Hogan at Phillips Petroleum . In 1953 the German chemist Karl Ziegler developed a catalytic system based on titanium halides and organoaluminium compounds that worked at even milder conditions than

4400-596: The copyright claims after the district court concluded that his two-second, four-beat sequence of dance steps was not protectable under copyright law. Polyethylene Polyethylene or polythene (abbreviated PE ; IUPAC name polyethene or poly(methylene) ) is the most commonly produced plastic . It is a polymer , primarily used for packaging ( plastic bags , plastic films , geomembranes and containers including bottles , cups , jars , etc.). As of 2017 , over 100 million tonnes of polyethylene resins are being produced annually, accounting for 34% of

4488-456: The different types of music chosen and the themes of the shows. Dance is incorporated into the show to complement equipment work and drill, and is performed as seamlessly throughout the show as any other movements. Winter Guard International is not only a national competition but it is also an organization that has been around for many years. Unlike other traditional sports, the rules and regulations have been changed and altered many times since

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4576-466: The failure to identify enzymes responsible for the proposed degradation. Another issue is that organisms are incapable of importing hydrocarbons of molecular weight greater than 500. The Indian mealmoth larvae are claimed to metabolize polyethylene based on observing that plastic bags at a researcher's home had small holes in them. Deducing that the hungry larvae must have digested the plastic somehow, he and his team analyzed their gut bacteria and found

4664-466: The form of UHMWPE fibers , have (as of 2005) begun to replace aramids in many high-strength applications. The properties of polyethylene depend strongly on type. The molecular weight, crosslinking, and presence of comonomers all strongly affect its properties. It is for this structure-property relation that intense effort has been invested into diverse kinds of PE. LDPE is softer and more transparent than HDPE. For medium- and high-density polyethylene

4752-476: The formation of free radicals at the ends of the growing polyethylene molecules. They cause new ethylene monomers to add to the ends of the molecules, rather than along the middle, causing the growth of a linear chain. HDPE has high tensile strength. It is used in products and packaging such as milk jugs, detergent bottles, butter tubs, garbage containers, and water pipes . PEX is a medium- to high-density polyethylene containing cross-link bonds introduced into

4840-550: The gas and water vapour permeability (only polar gases) is lower than for most plastics. Oxygen , carbon dioxide and flavorings , on the other hand, can pass it easily. Polyethylene burns slowly with a blue flame having a yellow tip and gives off an odour of paraffin (similar to candle flame). The material continues burning on removal of the flame source and produces a drip. Polyethylene cannot be imprinted or bonded with adhesives without pretreatment. High-strength joints are readily achieved with plastic welding . Polyethylene

4928-571: The guard. The dance instructors create and teach the movement choreography in the show. The drill instructors focus on the position of the guard members relative to one another and to the boundaries of the performance area, in addition to where each member goes at which specific time during the performance. In some cases, all of these roles are fulfilled by one sole director. A winter guard team usually has one or multiple captains or student leaders who serve as leaders as well as performing members. The captain may assume minor administrative duties and lead

5016-411: The local/regional level, such as Regional A, or Novice. In many places there is also a middle school class, often called Cadet . Scholastic A teams tend to be a step above the regional level and are the lowest level to compete in WGI. Scholastic Open teams are an intermediate level for competition. The Scholastic World division includes the highest caliber of winter guard teams. The Independent division

5104-528: The low pressure process α-olefins (e.g. 1-butene or 1-hexene ) may be added, which are incorporated in the polymer chain during polymerization. These copolymers introduce short side chains, thus crystallinity and density are reduced. As explained above, mechanical and thermal properties are changed thereby. In particular, PE-LLD is produced this way. Metallocene polyethylene (PE-M) is prepared by means of metallocene catalysts , usually including copolymers (z. B. ethene / hexene). Metallocene polyethylene has

5192-731: The main rules for choreography are that it must impose some kind of order on the performance, within the three dimensions of space as well the fourth dimension of time and the capabilities of the human body. In the performing arts , choreography applies to human movement and form. In dance , choreography is also known as dance choreography or dance composition. Choreography is also used in a variety of other fields, including opera , cheerleading , theatre , marching band , synchronized swimming , cinematography , ice skating , gymnastics , fashion shows , show choir , cardistry , video game production, and animated art . The International Choreographic Competition Hannover, Hanover , Germany,

5280-486: The material is heavier and more durable. Additionally, wood is less slick and can be weighed custom to someone's specifications. Plastic rifles tend to be a little more forgiving and easier to handle. Some people may not like plastic rifles because they can become slick and hard to handle, either when it's raining or just from the sweat from the user's hands. Some plastic rifles come with a manufacture's guarantee that they will not break under normal usage. Most are made out of

5368-985: The melting point is typically in the range 120 to 130 °C (248 to 266 °F). The melting point for average commercial low-density polyethylene is typically 105 to 115 °C (221 to 239 °F). These temperatures vary strongly with the type of polyethylene, but the theoretical upper limit of melting of polyethylene is reported to be 144 to 146 °C (291 to 295 °F). Combustion typically occurs above 349 °C (660 °F). Most LDPE , MDPE , and HDPE grades have excellent chemical resistance, meaning that they are not attacked by strong acids or strong bases and are resistant to gentle oxidants and reducing agents. Crystalline samples do not dissolve at room temperature. Polyethylene (other than cross-linked polyethylene) usually can be dissolved at elevated temperatures in aromatic hydrocarbons such as toluene or xylene , or in chlorinated solvents such as trichloroethane or trichlorobenzene . Polyethylene absorbs almost no water ;

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5456-409: The middle of a chain) are more stable than primary radicals (at the end of the chain), and tertiary radicals (at a branch point) are more stable yet. Each time an ethylene monomer is added, it creates a primary radical, but often these will rearrange to form more stable secondary or tertiary radicals. Addition of ethylene monomers to the secondary or tertiary sites creates branching. VLDPE is defined by

5544-624: The most important polyethylene grades are HDPE, LLDPE, and LDPE. UHMWPE is polyethylene with a molecular weight numbering in the millions, usually between 3.5 and 7.5 million amu . The high molecular weight makes it a very tough material, but results in less efficient packing of the chains into the crystal structure as evidenced by densities of less than high-density polyethylene (for example, 0.930–0.935 g/cm ). UHMWPE can be made through any catalyst technology, although Ziegler catalysts are most common. Because of its outstanding toughness and its cut, wear, and excellent chemical resistance, UHMWPE

5632-492: The nature and distribution of long chain branches in polyethylene. In HDPE, a relatively small number of these branches, perhaps one in 100 or 1,000 branches per backbone carbon, can significantly affect the rheological properties of the polymer. In addition to copolymerization with alpha-olefins, ethylene can be copolymerized with a wide range of other monomers and ionic composition that creates ionized free radicals. Common examples include vinyl acetate (the resulting product

5720-420: The performer's hands. Wooden rifles can be more challenging to use because each rifle is slightly different and may not be weighted precisely the same. Most wooden rifles are made of either poplar or aspen wood. It is recommended to tape wooden rifles as to keep the ends protected and make it more durable, as well as for cosmetics. Electrical tape is the first choice of most winter guards because you can get

5808-751: The polymer chains are branched, and the lower the molecular weight, the higher the crystallinity of polyethylene. Crystallinity ranges from 35% (PE-LD/PE-LLD) to 80% (PE-HD). Polyethylene has a density of 1.0 g/cm in crystalline regions and 0.86 g/cm in amorphous regions. An almost linear relationship exists between density and crystallinity. The degree of branching of the different types of polyethylene can be schematically represented as follows: [REDACTED] The figure shows polyethylene backbones, short-chain branches and side-chain branches. The polymer chains are represented linearly. The properties of polyethylene are highly dependent on type and number of chain branches. The chain branches in turn depend on

5896-422: The polymer structure, changing the thermoplastic into a thermoset . The high-temperature properties of the polymer are improved, its flow is reduced, and its chemical resistance is enhanced. PEX is used in some potable-water plumbing systems because tubes made of the material can be expanded to fit over a metal nipple and it will slowly return to its original shape, forming a permanent, water-tight connection. MDPE

5984-417: The popular game Fortnite. Hanagami published a YouTube video in 2017 featuring a dance he choreographed to the song "How Long" by Charlie Puth, and Hanagami claimed that Fortnight's "It's Complicated" "emote" copied a portion of his "How High" choreography. Hanagami's asserted claims for direct and contributory copyright infringement and unfair competition. Fortnite-maker Epic Games ultimately won dismissal of

6072-426: The process used: either the high-pressure process (only PE-LD) or the low-pressure process (all other PE grades). Low-density polyethylene is produced by the high-pressure process by radical polymerization, thereby numerous short chain branches as well as long chain branches are formed. Short chain branches are formed by intramolecular chain transfer reactions, they are always butyl or ethyl chain branches because

6160-415: The rates measured in the study methane production by plastics is presently an insignificant component of the global methane budget. Polyethylene may either be modified in the polymerization by polar or non-polar comonomers or after polymerization through polymer-analogous reactions. Common polymer-analogous reactions are in case of polyethylene crosslinking , chlorination and sulfochlorination . In

6248-529: The reaction proceeds after the following mechanism: The widespread usage of polyethylene poses potential difficulties for waste management because it is not readily biodegradable. Since 2008, Japan has increased plastic recycling, but still has a large amount of plastic wrapping which goes to waste. Plastic recycling in Japan is a potential US$ 90 billion market. It is possible to rapidly convert polyethylene to hydrogen and graphene by heating. The energy needed

6336-429: The rifles used in winter guard often weigh between 2 and 5 pounds (about 1–2.25 kilograms). Most winter guard rifles have a length of 30–39 inches (about 76–99 centimeters) and are composed of seven parts: Rifles can be made out of either wood or plastic . Some prefer plastic rifles because they are much more often the same weight and size if they are meant to be so. Others prefer wooden rifles because

6424-618: The rules and regulations for this activity. The rules that are written by WGI apply to every winter guard group competing in the World Championships no matter what country they are from. The World Championships are held every year in the United States. Most recently they have been held at the University of Dayton Arena in Dayton, Ohio with some prelims and semi-finals held elsewhere around the Dayton area and Cincinnati area. The phrase "Sport of

6512-495: The sabre by its blade. As with rifles, a piece of black or non-white tape placed near the center of rotation is used as a "spotter", making it easier to locate the fast-moving blade while it is rotating in the air. Sabres are used primarily by more advanced guard members. Guard members incorporate many different styles of dance into their shows. The most common styles of dance used are modern, contemporary, lyrical, jazz, and ballet. The different styles of dances are chosen depending on

6600-401: The same reason it is commonly used as the insulation material for high-frequency coaxial and twisted pair cables. Depending on thermal history and film thickness, PE can vary between almost clear ( transparent ), milky-opaque ( translucent ) and opaque . LDPE has the greatest, LLDPE slightly less, and HDPE the least transparency. Transparency is reduced by crystallites if they are larger than

6688-478: The so-called Ziegler–Natta catalysts . Another common catalyst is the Phillips catalyst , prepared by depositing chromium(VI) oxide on silica. Polyethylene can be produced through radical polymerization , but this route has only limited utility and typically requires high-pressure apparatus. Commonly used methods for joining polyethylene parts together include: Pressure-sensitive adhesives (PSA) are feasible if

6776-399: The surface chemistry or charge is modified with plasma activation , flame treatment , or corona treatment . Polyethylene is classified by its density and branching . Its mechanical properties depend significantly on variables such as the extent and type of branching, the crystal structure, and the molecular weight . There are several types of polyethylene: With regard to sold volumes,

6864-502: The tape in any color to match the show. Water is the main antagonist to wooden rifles; it can destroy a rifle and make it completely unusable. However, if cared for properly and used correctly, rifles can last for a long time. Sabres, which are designed much like the real sabres with the same name, are elegant sword-like pieces of equipment used in winter guard, with length ranging from about 30–39 inches (about 76–99 centimeters). They can either be plastic or metal, though metal

6952-401: The team when instructors are not available. The captain is also the representative of the guard during awards ceremonies. Most regional color guard circuits adopt the minimum and maximum performer requirements set by WGI, which varies by division. The Independent World classification has no maximum number of performers. The duration of winter guard shows depends on the class in which the guard

7040-470: The total plastics market. Many kinds of polyethylene are known, with most having the chemical formula (C 2 H 4 ) n . PE is usually a mixture of similar polymers of ethylene , with various values of n . It can be low-density or high-density and many variations thereof. Its properties can be modified further by crosslinking or copolymerization. All forms are nontoxic as well as chemically resilient, contributing to polyethylene's popularity as

7128-466: The two compounds. Ethylene/vinyl alcohol copolymer (EVOH) is (formally) a copolymer of PE and vinyl alcohol (ethenol), which is prepared by (partial) hydrolysis of ethylene-vinyl acetate copolymer (as vinyl alcohol itself is not stable). However, typically EVOH has a higher comonomer content than the VAC commonly used. EVOH is used in multilayer films for packaging as a barrier layer (barrier plastic). As EVOH

7216-1497: The victims of the 2019 El Paso Shooting . Contemporary Color is a 2016 documentary film directed by Turner Ross and Bill Ross IV featuring the performances of winter guard teams. The film was produced as a collaboration between David Byrne , Michael Gottwald, Dan Janvey and Josh Penn. Credits Winter Guard International (WGI) official website South Florida Winter Guard Association (SFWGA) official website Florida Federation of Colorguards Circuit (FFCC) official website Winter Guard Association of Southern California (WGASC) official website CGN - Color Guard Nederland WGUK - Winter Guard UK Colorguard Historical Society (CGHS) website Atlantic Indoor Association (AIA) website Ohio Indoor Performance Association (OIPA) website Mid-York Color Guard Circuit (MYCGC) website Northeast Color Guard Circuit (NECGC) website Michigan Color Guard Circuit (MCGC) website Mid-Atlantic Indoor Network (MAIN) website New England Scholastic Band Association (NESBA) website Southern Association for performance arts Midwest Color Guard Circuit Southeastern Colorguard Circuit Eastern Massachusetts Drum and Bugle Corps Association* Keystone Indoor Drill Association - MD & PA North Texas Colorguard Association (NTCA) website Northwest Pageantry Association (NWPA) website Sample Winterguard movement (Youtube) Rocky Mountain Color Guard Ohio Circuit Choreography Choreography

7304-458: The wavelength of visible light. The ingredient or monomer is ethylene ( IUPAC name ethene), a gaseous hydrocarbon with the formula C 2 H 4 , which can be viewed as a pair of methylene groups (− CH 2 −) connected to each other. Typical specifications for PE purity are <5 ppm for water, oxygen, and other alkenes contents. Acceptable contaminants include N 2 , ethane (common precursor to ethylene), and methane. Ethylene

7392-643: The white, waxy substance that he had created, they recognized that it contained long −CH 2 − chains and termed it polymethylene . The first industrially practical polyethylene synthesis (diazomethane is a notoriously unstable substance that is generally avoided in industrial syntheses) was again accidentally discovered in 1933 by Eric Fawcett and Reginald Gibson at the Imperial Chemical Industries (ICI) works in Northwich , England . Upon applying extremely high pressure (several hundred atmospheres ) to

7480-539: The winter guard activity is growing outside of the United States. In Europe, Color Guard Nederland (Netherlands) (CGN) and Winter Guard United Kingdom (WGUK) have recently affiliated with organizations from France and Germany to form the European Indoor Arts Alliance (EIAA) with the goal of creating a European Union-wide platform for the growth of the color guard activity in Europe, where the scholastic branch of

7568-631: The written record of dances, which later became known as dance notation , with the meaning of choreography shifting to its current use as the composition of a sequence of movements making up a dance performance. The ballet master or choreographer during this time became the "arranger of dance as a theatrical art", with one well-known master being of the late 18th century being Jean-Georges Noverre , with others following and developing techniques for specific types of dance, including Gasparo Angiolini , Jean Dauberval , Charles Didelot , and Salvatore Viganò . Ballet eventually developed its own vocabulary in

7656-661: Was found to have very low-loss properties at very high frequency radio waves, commercial distribution in Britain was suspended on the outbreak of World War II, secrecy imposed, and the new process was used to produce insulation for UHF and SHF coaxial cables of radar sets. During World War II, further research was done on the ICI process and in 1944, DuPont at Sabine River, Texas, and Union Carbide Corporation at South Charleston, West Virginia, began large-scale commercial production under license from ICI. The landmark breakthrough in

7744-519: Was introduced in 2020 in response to the COVID-19 pandemic, with a Grand Prix worth US$ 1,000 . Section 102(a)(4) of the Copyright Act provides protection in “choreographic works” that were created after January 1, 1978, and are fixed in a tangible medium of expression. Under copyright law, choreography is “the composition and arrangement of a related series of dance movements and patterns organized into

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