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58-462: Bangladeshi lawyer Dr. Mohiuddin Farooque established BELA in 1992 and was the first Chief Executive of the organization. From the very beginning BELA monitored compliance with Bangladesh's environmental Laws, took initiatives to increase environmental awareness and sought to ensure the development of proper environmental jurisprudence. BELA faced a serious shock after the death of Dr. Farooque in 1997 and

116-480: 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

174-532: A daughter, Nehla Siddique and two sons, Ahmed Zarir Siddique and Ahmed Zeedan Siddique. In April 2014, her husband Siddique, managing director of a garment factory owned by Nasrul Hamid Bipu , was briefly abducted by unknown individuals. Her first cousin Syed Liaquat Hasan is the current Upazila Chairman of Chunarughat Upazila , Habiganj . Polythene Polyethylene or polythene (abbreviated PE ; IUPAC name polyethene or poly(methylene) )

232-580: 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

290-458: 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

348-473: 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

406-587: A member of BELA, advocate Ms. Rizwana Hasan took over the direction of BELA. In 1994, election candidates for the Dhaka City Corporation were unlawfully campaigning in Old Dhaka in violation of the 1860s Environmental Law of Bangladesh. Rizwana Hasan brought suit in court and the Court judged it an unlawful act. Thereafter, Bangladesh Election Commission (EC) took initiatives to stop election campaigning that

464-501: 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

522-412: 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

580-487: 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

638-410: 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

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696-651: 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

754-462: 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

812-538: 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

870-551: 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

928-429: 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

986-529: Is harmful to the environment. Under the supervision of Rizwana Hasan, BELA started its war against the shipbreaking industry in Bangladesh. On behalf of BELA, Rizwana brought the first suit against the shipbreaking industry, accusing it of creating an unsafe work environment and producing environmentally unsafe waste. Bela then brought another three suits demanding rights for the workers and the banning in Bangladesh of ships carrying poisonous substances. And in 2003

1044-416: 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

1102-766: 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

1160-400: 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 the total plastics market. Many kinds of polyethylene are known, with most having

1218-448: 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

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1276-451: 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

1334-450: 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

1392-501: 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 ,

1450-827: The Global 500 Roll of Honor in 2003 by the United Nations Environment Program. She herself won: She has also been dubbed as a Hero of Environment by the American news magazine TIME . In 2022, Hasan received the International Women of Courage Award from the United States Department of State . Hasan was born in Habiganj to the parents Syed Mahibul Hasan and Suraiya Hasan. She married her classmate lawyer-entrepreneur Abu Bakar Siddique, and has

1508-552: The University of Dhaka for her bachelor's and master's degree in law. Hasan got involved in the shipbreaking industry, first suing the breaking yards in Chittagong in 2003 for, among other reasons, bringing health hazards to the workers, poor working conditions, and improper waste disposal. In response, in March 2003 the court declared shipbreaking without an environmental clearance from

1566-463: 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 a multi-use plastic. However, polyethylene's chemical resilience also makes it

1624-576: The interim government of Bangladesh and as Minister of Environment, Forest and Climate Change . As an environmentalist, her work is focused on regulations for the shipbreaking industry in Bangladesh, and was awarded the Goldman Environmental Prize in 2009. She was also awarded the Ramon Magsaysay Award in 2012 for her "uncompromising courage and impassioned leadership in a campaign of judicial activism in Bangladesh that affirms

1682-401: 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

1740-470: The 'Global 500 Roll of Honour' under United Nations Environmental Program (UNEP) in 2003. BELA, along with Dejusticia: The Center for Law, Justice and Society from Colombia and The Legal Agenda from Lebanon are joint winners of the 2020 Tang Prize in Rule of Law. Rizwana Hasan Syeda Rizwana Hasan (born 15 January 1968) is a Bangladeshi lawyer and environmentalist. She is currently an adviser to

1798-571: 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,

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1856-408: The appropriate department illegal. Hasan continues to strive for more labour rights and a safer working environment in the industry. She has also successfully sued organizations involved in filling lakes to build real estate, the improper use of polythene , hill cutting, deforestation , shrimp farming, and building illegal establishments on St. Martin's Island . Under Hasan's leadership, BELA won

1914-414: 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

1972-474: 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

2030-504: The court ruled that no ship will be allowed for shipbreaking without 'Environmental Clearance'. BELA also took other initiatives where the environment is under threat, including housing covering wetlands, unnecessary usage of polythene, cutting of hills, deforestation, shrimp cultivation, and unlawful construction in St. Martin's Island . In recent days, BELA opened a regular section in their headquarters where they receive legal complaints regarding

2088-585: The environment. BELA also sought judicial compensation from Naiko after the Tengratila Exploitation" in 2006. BELA published many books on Environmental Preservation and Law Enforcement for Environment. Some of the notables are: Beside that, BELA published "BELA Newsletter" in English and "Bela Barta" ( বেলা বার্তা ) in Bangla, two weekly supplements of their recent activities and timeline. BELA achieved

2146-466: 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

2204-466: 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

2262-476: 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

2320-550: 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

2378-528: 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

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2436-985: 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 ;

2494-409: 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

2552-624: 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

2610-492: 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

2668-564: The people's right to a good environment as nothing less than their right to dignity and life." Syeda Rizwana Hasan was born on 15 January 1968, into a Bengali Muslim Zamindar family called Narapati Haveli in Habiganj District , Bangladesh (previously East Pakistan ). She studied in Viqarunnisa Noon School and College for her secondary education and Holy Cross College for her higher secondary education, before attending

2726-751: 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

2784-422: 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

2842-426: 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

2900-415: 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

2958-529: 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

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3016-401: 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

3074-478: 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

3132-399: 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,

3190-466: 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

3248-458: 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

3306-643: 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

3364-661: 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

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