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Ziploc is an American brand of reusable, re-sealable sliding channel storage bags and containers originally developed and test marketed by Dow Chemical Company in 1968 and now produced by S. C. Johnson & Son .

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81-406: The plastic bags and containers come in different sizes for use with different products. The brand offers sandwich bags, snack bags and other bags for various purposes. In 1951, a company called Flexigrip, Inc. was formed to develop and market a plastic zipper by the same name. This zipper was based on a set of patents, which were purchased from their inventor, Borge Madsen. The initial products for

162-728: A better life-cycle analysis than compostable plastics . They added that "The current bags made from bioplastics have less favourable environmental impact profiles than the other materials examined" and that this is due to the process of raw-material production. Depending on the construction, plastic bags can be suited for plastic recycling . They can be incinerated in appropriate facilities for waste-to-energy conversion. They are stable and benign in sanitary landfills . If disposed of improperly, however, plastic bags can create unsightly litter and harm some types of wildlife . Plastic bags have low recycling rates due to lack of separation ability. Mixed material recycling causes contamination of

243-480: 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

324-450: A convenience to shoppers. Some stores charge a nominal fee for a bag. Heavy-duty reusable shopping bags are often considered environmentally better than single-use paper or plastic shopping bags . Because of environmental and litter problems, some locations are working toward a phase-out of lightweight plastic bags . American and European patent applications relating to the production of plastic shopping bags can be found dating back to

405-580: 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

486-458: 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

567-517: A hazard to small children. Plastic bags are used for diverse applications: 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

648-677: A line speed of 30 feet per minute, but none were being sold to consumers, because they were too expensive to produce. Dow assigned one of their inventors, R. Douglas Behr, to develop a high-speed, efficient process. Having little prior experience in plastics, the task was daunting for Behr, but he surpassed everyone in the world within a year. As he improved the process and increased line speeds to 60, then 90, then 150 and finally 300 feet per minute in 1972, he had to design new equipment. Some were patented and some were kept as trade secrets by Dow. Eventually, other research and production personnel, such as lab technician William Shrum and others, contributed to

729-501: A location that accepts plastic film. Usually, this means taking them back to the grocery store or another major retail store. Thin, conformable plastic bags, especially dry cleaning bags, have the potential to cause suffocation. Because of this, about 25 children in the United States suffocate each year due to plastic bags, almost nine-tenths of whom are under the age of one. This has led to voluntary warning labels on some bags posing

810-402: A minimum charge. In September 2014, California became the first state to pass a law banning their use, but the ban contained what has since been called a loophole, allowing supermarkets to provide thicker plastic bags as "reusable" bags at a cost of 10 cents each. In 2024, California passed a new law, taking effect in 2026, which closes this loophole and reinforces the original ban. In India,

891-501: 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

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972-552: 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

1053-415: A packaging materials war erupted, with plastic shopping bags at the center of highly publicized disputes. In 1992, Sonoco Products Company of Hartsville, SC patented the "self-opening polyethylene bag stack". The main innovation of this redesign is that the removal of a bag from the rack opens the next bag in the stack. The number of plastic bags used and discarded worldwide has been estimated to be on

1134-412: 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

1215-413: A simple, strong bag with a high load-carrying capacity, and was patented worldwide by Celloplast in 1965. From the mid-1980s onwards, plastic bags became common for carrying daily groceries from the store to vehicles and homes throughout the developed world. As plastic bags increasingly replaced paper bags, and as other plastic materials and products replaced glass, metal, stone, timber and other materials,

1296-409: A study from Clemson University, came to similar conclusions. Even though the bags are plastic, they typically cannot be recycled in curbside recycling bins. The material frequently causes the equipment used at recycling plants to jam, thus having to pause the recycle machinery and slow down daily operations. However, plastic bags are 100% recyclable. To recycle them the user needs to drop them off at

1377-456: A subsidiary of ITW. In 1991, ITW acquired Dow's interest in Zip-Pak, making Zip-Pak a fully-owned subsidiary of ITW. Zip-Pak produces plastic zippers for the food packaging market. From the time of inception until today, Flexigrip/Minigrip/Zip-Pak/Dow/Dow Brands have obtained over 300 patents for plastic zippers, zipper bags, and methods and machinery of producing the same. In 1997, Dow Chemical sold

1458-610: A variety of plastics films. Polyethylene ( LDPE , LLDPE , etc.) is the most common. Other forms, including laminates and co-extrusions can be used when the physical properties are needed. Plastics to create single use bags are primarily made with Fossil fuels . International Plastic Bag Free Day is celebrated on July 3. Plastic bags usually use less material than comparable to boxes, cartons, or jars, thus are often considered as "reduced or minimized packaging". In June 2009 Germany’s Institute for Energy and Environmental Research concluded that oil-based plastics, especially if recycled, have

1539-487: 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

1620-410: 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

1701-429: Is a highly competitive market with a lot of players and unusually strong private label sales." In 1992, Ziploc was faced with sudden competition from the booming sales of arch-rival First Brands Corporation's Glad-Lock bag. Glad Lock bags jumped 13.1% in 12 weeks in the end of 1992, giving Glad-Lock an 18.4% share of the market compared to Ziploc's 43% share. Plastic bag A plastic bag , poly bag , or pouch

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1782-659: Is a type of container made of thin, flexible, plastic film , nonwoven fabric , or plastic textile . Plastic bags are used for containing and transporting goods such as foods, produce, powders , ice, magazines , chemicals , and waste . It is a common form of packaging . Most plastic bags are heat sealed at the seams, while some are bonded with adhesives or are stitched. Many countries are introducing legislation to phase out lightweight plastic bags , because plastic never fully breaks down, causing everlasting pollution of plastics and environmental impacts. Every year, about 1 to 5 trillion plastic bags are used and discarded around

1863-651: 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

1944-462: 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

2025-538: 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

2106-551: 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

2187-429: 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

2268-416: 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

2349-766: 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

2430-448: 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

2511-451: 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

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2592-450: 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

2673-501: 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 ,

2754-401: 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

2835-418: The 2000s, many stores and companies began to use different types of biodegradable bags to comply with perceived environmental benefits. When plastic shopping bags are not disposed of properly, they can end up in streams, which then lead them to end up in the open ocean. To mitigate marine plastic pollution from single-use shopping bags, many jurisdictions around the world have implemented bans or fees on

2916-483: The Flexigrip and other plastic zippers (such as the sliderless zippers (toptite) that were developed by Flexigrip) were looseleaf binder inserts and flat briefcases. Thereafter, the marketing efforts were directed at packaging products in plastic zipper bags, which turned out to be the principal market for the Flexigrip, Inc. products. In 1961, Flexigrip, Inc. obtained from a Japanese company, Seisan Nippon Sha, which invented

2997-602: The Minigrip-type plastic zipper bag, exclusive manufacturing and selling rights for the United States, based on a series of Seisan plastic zipper patents. A company by the same name was formed to produce and market Minigrip bags. In or about 1964, Minigrip, Inc. negotiated an exclusive license for the grocery trade (supermarkets) with Dow Chemical Company for the Minigrip product. It turned out to be enormously successful. At that time, plastic bags were being produced in 25 countries at

3078-571: 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,

3159-526: The Recyc-Quebec, a Canadian recycling agency, "The conventional plastic bag has several environmental and economic advantages. Thin and light, its production requires little material and energy. It also avoids the production and purchase of garbage/bin liner bags since it benefits from a high reuse rate when reused for this purpose (77.7%)." Government studies from Denmark and the United Kingdom, as well as

3240-453: The United States, and many other countries. Ziploc's head of marketing is Scott Heim, who handles its multimillion-dollar advertisement campaigns. In 2002, S. C. Johnson launched its biggest campaign in history, a $ 50 million-plus campaign to launch a new line of disposable tableware /storage products to be marketed under the Ziploc brand name. S. C. Johnson tends to focus its campaigns in

3321-469: The animal body decomposes, the plastic reenters the environment, posing more potential problems. Huge masses of plastic waste are arriving in the oceans per annum and causing several damages which include risk of marine species, disturbance in food web ultimately effecting marine ecosystem, several microbial and alien species colonize on plastic particles enhancing their harmfulness, and plastic particles driven by winds form garbage patches in various parts of

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3402-414: 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

3483-498: The bags in this line are made with 25% less plastic and are manufactured using wind power. The Ziploc Evolve sandwich bag was so successful that it was deemed the "Best in Show" at the 2010 Best New Product Awards in Canada. S. C. Johnson & Son uses written, online, interactive, and televised commercial advertising for its Ziploc products. The advertisements run in: Brazil, Germany, Thailand,

3564-474: 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

3645-664: The direction of television commercials. In the 2002 campaign, $ 35 million was devoted to a television campaign. In 2015, it created an advertising campaign with Tough Mudder to advertise to mothers via an obstacle course. The manufacturing of Ziploc bags varies among different products. The ordinary Ziploc storage and freezer bag is made from polyethylene plastic. Ziploc faces strong competition from such competitors as Glad , Hefty , and many privately owned, generic, store brand plastic bags and containers. As Jules Rose, chairman of Sloan's Supermarkets Inc. in New York City, states: "This

3726-451: The early 1950s, but these refer to composite constructions with handles fixed to the bag in a secondary manufacturing process. The modern lightweight shopping bag is the invention of Swedish engineer Sten Gustaf Thulin. In the early 1960s, Thulin developed a method of forming a simple one-piece bag by folding, welding and die-cutting a flat tube of plastic for the packaging company Celloplast of Norrköping , Sweden. Thulin's design produced

3807-466: 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

3888-466: 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

3969-476: 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

4050-550: 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

4131-428: The government has banned the use of plastic bags of a thickness below 50 microns . In 2018, Montreal, Canada, also banned plastic bags with Ottawa expected to also put the ban into effect. Plastic bags are mostly made out of petroleum products and natural gas. 8% of the world's petroleum resources are used for creating plastic bags at 12 million barrels of oil a day. Half of that is used as materials to make them, and

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4212-718: The infection is a health risk. They are lightweight and flexible, so they can be carried by or laid next to patients without making the patient as uncomfortable as a heavy glass bottle would be. They are less expensive than re-usable options, such as glass bottles. Moderate quality evidence from a 2018 systematic review showed that plastic wraps or bags prevented hypothermia compared to routine care, especially in extremely preterm infants. Flexible intermediate bulk containers are large industrial containers, usually used for bulk powders or flowables. They are usually constructed of woven heavy-duty plastic fibers. Open bags with carrying handles are used in large numbers. Stores often provide them as

4293-498: The latter now discontinued. They have expandable bottom bags that stand on their own. The now-discontinued polypropylene Zip 'n Steam bags were used to cook food in a microwave oven. They also have had large bags, used for non-food storage, as big as 2 ft by 2.7 ft (0.61 m × 0.82 m). The now-disconued flexible totes made by Ziploc were used for non-food storage and were as big as 22 US gallons (83 L). Recently, Ziploc has made an evolved line of sandwich and storage bags. All

4374-528: 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

4455-445: The material. However, plastic bags are reused before discard at a rate of 1.6 times. Bags come with various features such as carrying handles, hanging holes, tape attachments, and security features. Some bags are designed for easy opening and have reclosable press-to-seal zipper strips. This feature is commonly found in empty kitchen bags and some food packaging. Some bags are sealed for tamper-evident capability, including some where

4536-985: 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 ;

4617-409: 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

4698-624: 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

4779-492: 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

4860-502: The oceans. Marine animals are not the only animals affected by improper plastic bag disposal. Sea birds, when hunting, sense for dimethyl sulfide (DMS) which is produced by algae. Plastic is a breeding ground for algae, so the sea birds mistakenly eat the bag rather than the fish that typically ingests algae. (National Geographic) Plastic bags do not do well in the environment, but several government studies have found them to be an environmentally friendly carryout bag option. According to

4941-473: The order of one trillion annually. The use of plastic bags differs dramatically across countries. While the average consumer in China uses only two or three plastic bags a year, the numbers are much higher in most other countries: Denmark: four; Ireland: 20; Germany: 65; Poland, Hungary, Slovakia: more than 400. A large number of cities and counties have banned the use of plastic bags by grocery stores or introduced

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5022-409: The other half for energy to make them. At this rate, it will soon run out, impacting many things that depend on the resource. Not to mention all the air pollution it causes. Non-compostable plastic bags can take up to 1000 years to decompose . Plastic bags are not capable of biodegradation but rather they photodegrade, a process by which the plastic bags are broken down into smaller toxic parts. In

5103-751: 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

5184-422: 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

5265-405: The press-to-reseal feature becomes accessible only when a perforated outer seal has torn away. Boil-in-bags are often used for sealed frozen foods, sometimes complete entrees. The bags are usually tough heat-sealed nylon or polyester to withstand the temperatures of boiling water. Some bags are porous or perforated to allow the hot water to contact the food: rice, noodles, etc. Grocery stores are

5346-627: The process development, but Behr continued to be the leading researcher until he retired in 1993 as a senior associate scientist. At that time the research building was "Dedicated in Recognition of the Distinguished Career of R. Douglas Behr". In 1978, Minigrip was acquired by Signode, Inc. and became a subsidiary of that company. In 1986, Signode and Dow formed a company, namely Zippak, to develop zipper bags for food products. In 1987, Illinois Tool Works (ITW) acquired Signode, and Minigrip became

5427-426: 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

5508-415: 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

5589-529: 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

5670-498: The rights of DowBrands, which included Ziploc, to S. C. Johnson & Son for between $ 1.3 and $ 1.7 billion. Zip-Pak developed polypropylene-compatible zippers in 2003. Among Ziploc and Zip-Pak's competitors are Presto, a subsidiary of Reynolds , and Pactiv Evergreen . In 1995, Hefty , one of Reynolds' holdings, introduced a sliding zipper bag. Ziploc has expanded their products to more than just sandwich bags. Ziploc products have varied from freezer bags to Twist 'n Loc containers,

5751-401: 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

5832-515: The single largest supplier of single-use plastic bags. Bag-in-box packaging is often used for liquids such as box wine and institutional sizes of other liquids. Plastic bags are used for many medical purposes. The non-porous quality of plastic film means that they are useful for isolating infectious body fluids; other porous bags made of nonwoven plastics can be sterilized by gas and maintain this sterility. Bags can be made under regulated sterile manufacturing conditions, so they can be used when

5913-478: 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

5994-399: 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,

6075-470: 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

6156-466: 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

6237-469: The use of plastic bags. An estimated 300 million plastic bags end up in the Atlantic Ocean alone. The way in which the bags float in open water can resemble a jellyfish , posing significant dangers to marine mammals and Leatherback sea turtles , when they are eaten by mistake and enter the animals' digestive tracts. After ingestion, the plastic material can lead to premature death. Once death occurs and

6318-458: 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

6399-643: 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

6480-492: The world. From point of sale to destination, plastic bags have a lifetime of 12 minutes. Approximately 320 bags per capita were used in 2014 in the United States of America. Several design options and features are available. Some bags have gussets to allow a higher volume of contents, special stand-up pouches have the ability to stand up on a shelf or a refrigerator, and some have easy-opening or reclosable options. Handles are cut into or added into some. Bags can be made with

6561-661: 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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