Plastic

Plastics are a wide range of synthetic or semisynthetic materials composed primarily of polymers. Their defining characteristic, plasticity, allows them to be molded, extruded, or pressed into a diverse range of solid forms. This adaptability, combined with a wide range of other properties such as low weight, durability, flexibility, chemical resistance, low toxicity, and low-cost production, has led to their widespread use around the world. While most plastics are produced from natural gas and petroleum, a growing minority are produced from renewable resources like polylactic acid. Between 1950 and 2017, 9.2 billion metric tons of plastic are estimated to have been made, with more than half of this amount being produced since 2004. In 2023 alone, preliminary figures indicate that over 400 million metric tons of plastic were produced worldwide. If global trends in plastic demand continue, it is projected that annual global plastic production will exceed 1.3 billion tons by 2060. The primary uses for plastic include packaging, which makes up about 40% of its usage, and building and construction, which makes up about 20% of its usage. The success and dominance of plastics since the early 20th century have had major benefits for mankind, ranging from medical devices to lightweight construction materials.…

Plastics are a wide range of synthetic or semisynthetic materials composed primarily of polymers. Their defining characteristic, plasticity, allows them to be molded, extruded, or pressed into a diverse range of solid forms. This adaptability, combined with a wide range of other properties such as low weight, durability, flexibility, chemical resistance, low toxicity, and low-cost production, has led to their widespread use around the world. While most plastics are produced from natural gas and petroleum, a growing minority are produced from renewable resources like polylactic acid. Between 1950 and 2017, 9.2 billion metric tons of plastic are estimated to have been made, with more than half of this amount being produced since 2004. In 2023 alone, preliminary figures indicate that over 400 million metric tons of plastic were produced worldwide. If global trends in plastic demand continue, it is projected that annual global plastic production will exceed 1.3 billion tons by 2060. The primary uses for plastic include packaging, which makes up about 40% of its usage, and building and construction, which makes up about 20% of its usage. The success and dominance of plastics since the early 20th century have had major benefits for mankind, ranging from medical devices to lightweight construction materials. The sewage systems in many countries rely on the resiliency and adaptability of polyvinyl chloride. It is also true that plastics are the basis of widespread environmental concerns, due to their slow decomposition rate in natural ecosystems. Most plastic produced has not been reused, thus the need for microplastic remediation. Some are unsuitable for reuse. Much ends up in landfills or as plastic pollution. Particular concern focuses on microplastics. Marine plastic pollution, for example, creates garbage patches. Of all the plastic discarded so far, some 14% has been incinerated and less than 10% has been recycled. In developed economies, about a third of plastic is used in packaging and roughly the same in buildings in applications such as piping, plumbing or vinyl siding. Other uses include automobiles (up to 20% plastic ), furniture, and toys. In the developing world, the applications of plastic may differ; 42% of India's consumption is used in packaging. Worldwide, about 50&nbsp;kg of plastic is produced annually per person, with production doubling every ten years. The world's first fully synthetic plastic was Bakelite, invented in New York in 1907 by Leo Baekeland, who coined the term plastics. Dozens of different types of plastics are produced today, such as polyethylene, which is widely used in product packaging, and polyvinyl chloride (PVC), used in construction and pipes because of its strength and durability. Many chemists have contributed to the materials science of plastics, including Nobel laureate Hermann Staudinger, who has been called "the father of polymer chemistry", and Herman Mark, known as "the father of polymer physics". ==Etymology== The word plastic derives from the Ancient Greek ( ), meaning "capable of being shaped or molded," which itself comes from ( ), meaning "molded" or "formed." In modern usage, the word plastic most commonly refers to the solid synthetic products of petrochemical-derived manufacturing. The word plasticity, as a noun, specifically refers to the deformability of the materials used in the manufacture of plastics. Plasticity allows molding, extrusion, or compression into a variety of shapes, including films, fibers, plates, tubes, bottles, and boxes, among many others. In materials science, plasticity also has a more technical definition, describing the nonreversible change in form of solid substances when subjected to external forces. However, this definition extends beyond the scope of this article. ==Classifications== Plastics are usually classified by their chemical structure of the polymer's backbone and side chains. Important groups classified in this way include the acrylics, polyesters, silicones, polyurethanes, and halogenated plastics. Plastics can be classified by the chemical process used in their synthesis, such as condensation, polyaddition, and cross-linking. They can also be classified by their physical properties, including hardness, density, tensile strength, thermal resistance, and glass transition temperature. Plastics can additionally be classified by their resistance and reactions to various substances and processes, such as exposure to organic solvents, oxidation, and ionizing radiation. Other classifications of plastics are based on qualities relevant to manufacturing or product design for a particular purpose. Examples include thermoplastics, thermosets, conductive polymers, biodegradable plastics, engineering plastics and elastomers. ===Thermoplastics and thermosetting polymers=== One important classification of plastics is the degree to which the chemical processes used to make them are reversible or not. Thermoplastics do not undergo chemical change in their composition when heated and thus can be molded repeatedly. Examples include polyethylene (PE), polypropylene (PP), polystyrene (PS), and polyvinyl chloride (PVC). Thermosetting polymers, also known as thermosets, can melt and take shape only once: after they have solidified, they stay solid and retain their shape permanently. If reheated, thermosets decompose rather than melt. Examples of thermosets include epoxy resin, polyimide, and Bakelite. The vulcanization of rubber is an example of this process. Before heating in the presence of sulfur, natural rubber (polyisoprene) is a sticky, slightly runny material, and after vulcanization, the product is dry and rigid. ===Amorphous and crystalline plastics=== Many plastics are amorphous, meaning they lack a highly ordered molecular structure. Crystalline plastics exhibit a pattern of more regularly spaced atoms, such as high-density polyethylene (HDPE), polybutylene terephthalate (PBT), and polyether ether ketone (PEEK). However, some plastics are partially amorphous and partially crystalline in molecular structure, giving them both a melting point and one or more glass transitions (the temperature above which the extent of localized molecular flexibility is substantially increased). These so-called semi-crystalline plastics include polyethylene, polypropylene, polyvinyl chloride, polyamides (nylons), polyesters and some polyurethanes. ===Conductive polymers=== Conductive polymers include certain kinds of polyacetylene, which attracted much academic interest. Conductivities as high as 80 kilosiemens per centimeter (kS/cm) have been achieved in such materials, although that value is not comparable to that of copper (60 MS/cm). A practical conductive plastic is poly(3,4-ethylenedioxythiophene) polystyrene sulfonate. ===Biodegradable plastics and bioplastics=== ====Biodegradable plastics==== Biodegradable plastics are plastics that are designed to degrade (break down) after use through exposure to biological factors, such as sunlight, ultraviolet radiation, moisture, bacteria, insects, enzymes, or wind abrasion. The most popular such materials are polylactic acids (PLAs), which have the added attraction that they are derived from non-petrochemical, renewable materials. PLAs have achieved only limited commercial success. ====Bioplastics==== While most plastics are produced from petrochemicals, bioplastics are made substantially from renewable plant materials like cellulose and starch. Due both to the finite limits of fossil fuel reserves and to rising levels of greenhouse gases caused primarily by the burning of those fuels, the development of bioplastics is a growing field. Global production capacity for bio-based plastics is estimated at 327,000 tonnes per year. In contrast, global production of polyethylene (PE) and polypropylene (PP), the world's leading petrochemical-derived polyolefins, was estimated at over 150 million tonnes in 2015. ==Plastic industry== The plastic industry includes the global production, compounding, conversion and sale of plastic products. Although the Middle East and Russia produce most of the required petrochemical raw materials, the production of plastic is concentrated in the global East and West. The plastic industry comprises a huge number of companies and can be divided into several sectors: ===Production=== Between 1950 and 2017, 9.2 billion tonnes of plastic are estimated to have been made, with more than half of this having been produced since 2004. Since the birth of the plastic industry in the 1950s, global production has increased enormously, reaching 400 million tonnes a year in 2021; this is up from 381 million metric tonnes in 2015 (excluding additives). From the 1950s, rapid growth occurred in the use of plastics for packaging, in building and construction, and in other sectors. If global trends on plastic demand continue, it is estimated that by 2050 annual global plastic production will exceed 1.1-billion tonnes annually. File:Slovnaft - new polypropylene plant PP3.JPG|A Slovnaft facility in Bratislava, Slovakia File:Ilham Aliyev, Italian President Sergio Mattarella attended inauguration of polypropylene plant constructed in Sumgayit Chemical Industrial Park under SOCAR Polymer project 32.jpg|A SOCAR Polymer polypropylene plant in Sumgayit, Azerbaijan Plastics are produced in chemical plants by the polymerization of their starting materials (monomers); which are almost always petrochemical in nature. Such facilities are normally large and are visually similar to oil refineries, with sprawling pipework running throughout. The large size of these plants allows them to exploit economies of scale. Despite this, plastic production is not particularly monopolized, with about 100 companies accounting for 90% of global production. This includes a mixture of private and state-owned enterprises. Roughly half of all production takes place in East Asia, with China being the largest single producer. Major international producers include: BASF Braskem Dow Chemical ExxonMobil Indorama Ventures LyondellBasell SABIC Shin-Etsu Chemical Sibur Sinopec Historically, Europe and North America have dominated global plastics production. However, since 2010 Asia has emerged as a significant producer, with China accounting for 31% of total plastic resin production in 2020. Regional differences in the volume of plastics production are driven by user demand, the price of fossil fuel feedstocks, and investments made in the petrochemical industry. For example, since 2010 over US$200&nbsp;billion has been invested in the United States in new plastic and chemical plants, stimulated by the low cost of raw materials. In the European Union (EU), too, heavy investments have been made in the plastics industry, which employs over 1.6-million people with a turnover of more than 360 billion euros per year. In China in 2016 there were over 15,000 plastic manufacturing companies, generating more than US$366&nbsp;billion in revenue. In 2017, the global plastics market was dominated by thermoplastics– polymers that can be melted and recast. Thermoplastics include polyethylene (PE), polyethylene terephthalate (PET), polypropylene (PP), polyvinyl chloride (PVC), polystyrene (PS), and synthetic fibers, which together represent 86% of all plastics. ===Compounding=== material]] Plastic is not sold as a pure unadulterated substance but is instead mixed with various chemicals and other materials. These additives include substances such as stabilizers, plasticizers, and dyes, which are intended to improve the lifespan, workability, or appearance of the final item. In some cases, two types of polymers are combined to form a polymer blend, such as high impact polystyrene. Large companies may do their own compounding prior to production, but some producers have it done by a third party. Companies that specialize in this work are known as Compounders. The compounding of thermosetting plastic is relatively straightforward; as it remains liquid until it is cured into its final form. For thermosoftening materials, which are used to make the majority of products, it is necessary to melt the plastic in order to mix-in the additives. This involves heating it to anywhere between . Molten plastic is viscous and exhibits laminar flow, leading to poor mixing. Compounding is therefore done using extrusion equipment, which is able to supply the necessary heat and mixing to give a properly dispersed product. The concentrations of most additives are usually quite low, however high levels can be added to create Masterbatch products. The additives in these are concentrated but still properly dispersed in the host resin. Masterbatch granules can be mixed with cheaper bulk polymer and will release their additives during processing to give a homogeneous final product. This can be cheaper than working with a fully compounded material and is particularly common for the introduction of color. ===Converting=== Converters (sometimes known as processors) are companies or specialists that fabricate finished plastic products from raw materials, often in the form of resins, pellets, or films. Injection molding: involves injecting molten plastic into a mold cavity under high pressure. The plastic solidifies in the mold to form the desired shape. Blow molding: involves heating a plastic tube called a parison and inflating it inside a mold to form hollow products such as bottles and toys. Rotational molding: involves rotating a mold on two axes while it is heated. Plastic powder is added to the mold and melts and sticks to the walls as the mold is rotated, which forms thick-walled hollow parts such as intermediate bulk containers. Casting: involves pouring liquid resin into a mold where it solidifies into a predesigned shape. Film blowing: involves heating a polymer and blowing it into a thin, continuous sheet. Commonly used for making polyethylene and polypropylene films used in packaging. Spinning: involves transforming a polymer melt or solution into continuous strands 3D printing: involves three-dimensionally printing an object layer by layer following a digital model using computer-aided design software. For thermosetting materials, the process is slightly different, as the plastics are liquid to begin with and but must be cured to give solid products, but much of the equipment is broadly similar. The most commonly produced plastic consumer products include packaging made from LDPE (e.g. bags, containers, food packaging film), containers made from HDPE (e.g. milk bottles, shampoo bottles, ice cream tubs), and PET (e.g. bottles for water and other drinks). Together these products account for around 36% of plastics use in the world. Most of them (e.g. disposable cups, plates, cutlery, takeaway containers, carrier bags) are used for only a short period, many for less than a day. The use of plastics in building and construction, textiles, transportation and electrical equipment also accounts for a substantial share of the plastics market. Plastic items used for such purposes generally have longer life spans. They may be in use for periods ranging from around five years (e.g. textiles and electrical equipment) to more than 20 years (e.g. construction materials, industrial machinery). Plastic consumption differs among countries and communities, with some form of plastic having made its way into most people's lives. North America (i.e. the North American Free Trade Agreement or NAFTA region) accounts for 21% of global plastic consumption, closely followed by China (20%) and Western Europe (18%). In North America and Europe, there is high per capita plastic consumption (94&nbsp;kg and 85&nbsp;kg/capita/year, respectively). In China, there is lower per capita consumption (58&nbsp;kg/capita/year), but high consumption nationally because of its large population. ==Gallery== PET Bottle Water.jpg|Water bottles made of PET File:HDPE bottles and containers.png|High density polythene (HDPE) is used for making sturdy containers; transparent containers may be made of PET. Pulling on the hood of the Tyveck suit (5429334133).jpg|Disposable suits can be made from non-woven HDPE fabric. Registered Mail Royal Mail - Great Britain-Germany 2017 - envelope front side.jpg|Plastic mailing envelopes made of HDPE A Ziploc bag made from LDPE.jpg|A Ziploc bag made of LDPE Daujėnų naminė duona.JPG|Food wrap made of LDPE Image-from-rawpixel-id-5957725-original.jpg|Metalized polypropylene film is a commonly used snack pack material. Kinder Joy 01.jpg|Kinder Joy shell made of polypropylene Red Polypropylene Chair with Stainless Steel Structure.JPG|A polypropylene chair Hanoi Vietnam The-omnipresent-plastic-chairs-01.jpg|Stools made of HDPE Polistirolo.JPG|Expanded polystyrene foam ("Thermocol") Styrofoam-grey-board.jpg|Extruded polystyrene foam ("Styrofoam") Have a Nice Day! styrofoam food container.JPG|Thermocol take-away food container Plastic egg carton.jpg|Egg tray made of PETE LDPE Foam.jpg|A piece of packaging foam made of LDPE Urethane sponge1.jpg|A kitchen sponge made of polyurethane foam Frying pan.jpeg|Non-stick cookware with Teflon coating IPhone 5c blue back.jpg|iPhone 5c, a smartphone with a polycarbonate "unibody" shell KelpAquarium.jpg|To withstand the extreme water pressure, this deep Monterey Bay Aquarium tank has windows made of acrylic glass up to 33&nbsp;cm thick. Plastic tubing.jpg|alt=|PVC pipes Pills in blister pack.jpg|PVC blister pack ==Applications== The largest application for plastics is as packaging materials, but they are used in a wide range of other sectors, including: construction (pipes, gutters, door and windows), textiles (stretchable fabrics, fleece), consumer goods (toys, tableware, toothbrushes), transportation (headlights, bumpers, body panels, wing mirrors), electronics (phones, computers, televisions) and as machine parts. In optics, plastics are used to manufacture aspheric lenses. ==Additives== Additives are chemicals blended into plastics to improved their performance or appearance. Additives are therefore one of the reasons why plastic is used so widely. Plastics are composed of chains of polymers. Many different chemicals are used as plastic additives. A randomly chosen plastic product generally contains around 20 additives. The identities and concentrations of additives are generally not listed on products. In the EU, over 400 additives are used in high volumes. In a global market analysis, 5,500 additives were found. At a minimum, all plastic contains some polymer stabilizers which permit them to be melt-processed (molded) without suffering polymer degradation. Additives in polyvinyl chloride (PVC), used widely for sanitary plumbing, can constitute up to 80% of the total volume. Unadulterated plastic (barefoot resin) is rarely sold. ====Poor countries==== Additives can also be problematic if waste is burned, especially when burning is uncontrolled or takes place in low-technology incinerators, as is common in many developing countries. Incomplete combustion can cause emissions of hazardous substances such as acid gases and ash, which can contain persistent organic pollutants (POPs) such as dioxins. A number of additives identified as hazardous to humans and/or the environment are regulated internationally. The Stockholm Convention on Persistent Organic Pollutants is a global treaty to protect human health and the environment from chemicals that remain intact in the environment for long periods, become widely distributed geographically, accumulate in the fatty tissue of humans and wildlife, and have harmful impacts on human health or on the environment. The use of bisphenol A (BPA) in plastic baby bottles is banned in many parts of the world but is not restricted in some low-income countries. ====Animals==== In 2023, plasticosis, a new disease caused by the ingestion of plastic waste, was discovered in seabirds. Birds affected with this disease were found to have scarred and inflamed digestive tracts, which can impair their ability to digest food. "When birds ingest small pieces of plastic, they found, it inflames the digestive tract. Over time, the persistent inflammation causes tissues to become scarred and disfigured, affecting digestion, growth and survival." ==Health effects== Plastics per se have low toxicity due to their insolubility in water and because they have a large molecular weight. They are biochemically inert. Additives in plastic products can be more problematic. For example, plasticizers like adipates and phthalates are often added to brittle plastics like PVC to make them pliable. Traces of these compounds can leach out of the product. Owing to concerns over the effects of such leachates, the EU has restricted the use of DEHP (di-2-ethylhexyl phthalate) and other phthalates in some applications, and the US has limited the use of DEHP, DPB, BBP, DINP, DIDP, and DnOP in children's toys and child-care articles through the Consumer Product Safety Improvement Act. It is a myth that using plastic bottles or food packages causes cancer in humans, even if the packaging is microwaved. Alkylphenols may cause environmental contamination. While a finished plastic may be non-toxic, the monomers used in the manufacture of its parent polymers may be toxic. In some cases, small amounts of those chemicals can remain trapped in the product unless suitable processing is employed. For example, the World Health Organization's International Agency for Research on Cancer (IARC) has recognized vinyl chloride, the precursor to PVC, as a human carcinogen. ===Bisphenol A (BPA)=== Some plastic products degrade to chemicals with estrogenic activity. The primary building block of polycarbonates, bisphenol A (BPA), is an estrogen-like endocrine disruptor that may leach into food. Research in Environmental Health Perspectives finds that BPA leached from the lining of tin cans, dental sealants and polycarbonate bottles can increase the body weight of lab animals' offspring. A more recent animal study suggests that even low-level exposure to BPA results in insulin resistance, which can lead to inflammation and heart disease. As of January 2010, the Los Angeles Times reported that the US Food and Drug Administration (FDA) is spending $30&nbsp;million to investigate indications of BPA's link to cancer. Bis(2-ethylhexyl) adipate, present in plastic wrap based on PVC, is also of concern, as are the volatile organic compounds present in new car smell. The EU has a permanent ban on the use of phthalates in toys. In 2009, the US government banned certain types of phthalates commonly used in plastic. ==Environmental effects== Estimates differ as to the amount of plastic waste produced in the last century. By one estimate, one billion tons of plastic waste have been discarded since the 1950s. Others estimate a cumulative human production of 8.3-billion tons of plastic, of which 6.3-billion tons is waste, with only 9% getting recycled. It is estimated that this waste is made up of 81% polymer resin, 13% polymer fibers and 32% additives. In 2018 more than 343 million tons of plastic waste were generated, 90% of which was composed of post-consumer plastic waste (industrial, agricultural, commercial and municipal plastic waste). The rest was pre-consumer waste from resin production and manufacturing of plastic products (e.g. materials rejected due to unsuitable color, hardness, or processing characteristics). The Ocean Conservancy reported that China, Indonesia, Philippines, Thailand, and Vietnam dump more plastic into the sea than all other countries combined. The rivers Yangtze, Indus, Yellow, Hai, Nile, Ganges, Pearl, Amur, Niger, and Mekong "transport 88% to 95% of the global [plastics] load into the sea." The presence of plastics, particularly microplastics, within the food chain is increasing. In the 1960s microplastics were observed in the guts of seabirds, and since then have been found in increasing concentrations. The long-term effects of plastics in the food chain are poorly understood. In 2009 it was estimated that 10% of modern waste was plastic, although estimates vary according to region. Meanwhile, 50% to 80% of debris in marine areas is plastic. Plastic is often used in agriculture. There is more plastic in the soil than in the oceans. The presence of plastic in the environment hurts ecosystems and human health. Research on the environmental impacts has typically focused on the disposal phase. However, the production of plastics is also responsible for substantial environmental, health and socioeconomic impacts. Prior to the Montreal Protocol, CFCs had been commonly used in the manufacture of the plastic polystyrene, the production of which had contributed to depletion of the ozone layer. Efforts to minimize environmental impact of plastics may include lowering of plastics production and use, waste- and recycling-policies, and the proactive development and deployment of alternatives to plastics such as for sustainable packaging. ===Decomposition of plastics=== Plastics degrade by a variety of processes, the most significant of which are hydrolysis and photo-oxidation. Chemical structure determines the fate of a polymers. Hence, decomposition pathways can be evaluated according to polymer types of major polymers. They are by volume: polyolefins (polyethyene, polypropylene, polystyrene), polyvinyl chloride, polyethylene terephthalate (PET). In general the degradability of a polymer correlates with the presence of functional groups (esters, amides). Polyolefins, which lack functional groups, degrade very slowly, especially polyethylene. In the case of polyethylene, degradation is attributed to reactions of defects within the polymer chain, such as alkene groups. PET, a polyester, degrades relatively quickly by multiple pathways, including ester hydrolysis and photooxidation. Whereas the other main polymers are stable to > 400 °C, PVC degrades at <300 °C. The process entails loss of hydrogen chloride (HCl). The evolved HCl catalyzes degradation of the PVC, thus much effort is devoted to capturing the HCl by mixing the PVC with additives. Microbial species capable of degrading plastics are known, but remain curiosities. Phenol-formaldehyde, commonly known as Bakelite, is degraded by the white rot fungus P. chrysosporium. ===Recycling=== ===Production of plastics=== Production of plastics from crude oil requires 7.9 to 13.7 kWh/lb (taking into account the average efficiency of US utility stations of 35%). Producing silicon and semiconductors for modern electronic equipment is even more energy consuming: 29.2 to 29.8 kWh/lb for silicon, and about 381 kWh/lb for semiconductors. This is much higher than the energy needed to produce many other materials. For example, to produce iron (from iron ore) requires 2.5-3.2 kWh/lb of energy; glass (from sand, etc.) 2.3–4.4 kWh/lb; steel (from iron) 2.5–6.4 kWh/lb; and paper (from timber) 3.2–6.4 kWh/lb. ===Incineration of plastics=== Quickly burning plastics at very high temperatures breaks down many toxic components, such as dioxins and furans. This approach is widely used in municipal solid waste incineration. Municipal solid waste incinerators also normally treat the flue gas to decrease pollutants further, which is needed because uncontrolled incineration of plastic produces carcinogenic polychlorinated dibenzo-p-dioxins. Open-air burning of plastic occurs at lower temperatures and normally releases such toxic fumes. In the European Union, municipal waste incineration is regulated by the Industrial Emissions Directive, which stipulates a minimum temperature of 850&nbsp;°C for at least two seconds. ===Facilitation of natural degradation=== The bacterium Blaptica dubia is claimed to help degradation of commercial polysterene. This biodegradation seems to occur in some plastic degrading bacteria inhabiting the gut of cockroaches. The biodegradation products have been found in their feces too. Research has been performed evaluating the feasibility of including bacteria in plastic or using it to degrade plastic at scale. ==History== The development of plastics has evolved from the use of naturally plastic materials (e.g., gums and shellac) to the use of the chemical modification of those materials (e.g., natural rubber, cellulose, collagen, and milk proteins), and finally to completely synthetic plastics (e.g., Bakelite, epoxy, and PVC). Early plastics were bio-derived materials such as egg and blood proteins, which are organic polymers. In around 1600 BC, Mesoamericans used natural rubber for balls, bands, and figurines. Treated cattle horns were used as windows for lanterns in the Middle Ages. Materials that mimicked the properties of horns were developed by treating milk proteins with lye. In the nineteenth century, as chemistry developed during the Industrial Revolution, many materials were reported. The development of plastics accelerated with Charles Goodyear's 1839 discovery of vulcanization to harden natural rubber. Parkesine, invented by Alexander Parkes in 1855 and patented the following year, is considered the first man-made plastic. It was manufactured from cellulose (the major component of plant cell walls) treated with nitric acid as a solvent. The output of the process (commonly known as cellulose nitrate or pyroxilin) could be dissolved in alcohol and hardened into a transparent and elastic material that could be molded when heated. By incorporating pigments into the product, it could be made to resemble ivory. Parkesine was unveiled at the 1862 International Exhibition in London and garnered for Parkes the bronze medal. In 1893, French chemist Auguste Trillat discovered the means to insolubilize casein (milk proteins) by immersion in formaldehyde, producing material marketed as galalith. In 1897, mass-printing press owner Wilhelm Krische of Hanover, Germany, was commissioned to develop an alternative to blackboards. The resultant horn-like plastic made from casein was developed in cooperation with the Austrian chemist (Friedrich) Adolph Spitteler (1846–1940). Although unsuitable for the intended purpose, other uses would be discovered. The world's first fully synthetic plastic was Bakelite, invented in New York in 1907 by Leo Baekeland, who coined the term plastics. Many chemists have contributed to the materials science of plastics, including Nobel laureate Hermann Staudinger, who has been called "the father of polymer chemistry", and Herman Mark, known as "the father of polymer physics". After World War I, improvements in chemistry led to an explosion of new forms of plastics, with mass production beginning in the 1940s and 1950s. Among the earliest examples in the wave of new polymers were polystyrene (first produced by BASF in the 1930s) and polyvinyl chloride (first created in 1872 but commercially produced in the late 1920s). In 1923, Durite Plastics, Inc., was the first manufacturer of phenol-furfural resins. In 1933, polyethylene was discovered by Imperial Chemical Industries (ICI) researchers Reginald Gibson and Eric Fawcett. The discovery of polyethylene terephthalate (PETE) is credited to employees of the Calico Printers' Association in the UK in 1941; it was licensed to DuPont for the US and ICI otherwise, and as one of the few plastics appropriate as a replacement for glass in many circumstances, resulting in widespread use for bottles in Europe. In 1954 polypropylene was discovered by Giulio Natta and began to be manufactured in 1957. Also in 1954 expanded polystyrene (used for building insulation, packaging, and cups) was invented by Dow Chemical. Since the 1960s, plastic production has surged with the advent of polycarbonate and HDPE, widely used in various products. In the 1980s and 1990s, plastic recycling and the development of biodegradable plastics began to flourish to mitigate environmental impacts. From 2000 to the present, bioplastics from renewable sources and awareness of microplastics have spurred extensive research and policies to control plastic pollution. ==Further reading== Gardiner, Beth (2026). Plastic Inc.: The Secret History and Shocking Future of Big Oil's Biggest Bet. Avery. ISBN 978-0593717103.

Text derived from https://en.wikipedia.org/w/index.php?oldid=1378203464 under CC BY-SA 4.0; modifications have been made.