
Plastics are a wide range of
synthetic or
semisynthetic materials composed primarily of
polymers
A polymer () is a substance or material that consists of very large molecules, or macromolecules, that are constituted by many repeating subunits derived from one or more species of monomers. Due to their broad spectrum of properties, b ...
. Their defining characteristic,
plasticity, allows them to be
molded,
extruded
Extrusion is a process used to create objects of a fixed cross-sectional profile by pushing material through a die of the desired cross-section. Its two main advantages over other manufacturing processes are its ability to create very complex ...
, 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
Natural gas (also fossil gas, methane gas, and gas) is a naturally occurring compound of gaseous hydrocarbons, primarily methane (95%), small amounts of higher alkanes, and traces of carbon dioxide and nitrogen, hydrogen sulfide and helium ...
and
petroleum
Petroleum, also known as crude oil or simply oil, is a naturally occurring, yellowish-black liquid chemical mixture found in geological formations, consisting mainly of hydrocarbons. The term ''petroleum'' refers both to naturally occurring un ...
, 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 has had major benefits for mankind, ranging from medical devices to light-weight construction materials. The sewage systems in many countries relies on the resiliency and adaptability of ]polyvinyl chloride
Polyvinyl chloride (alternatively: poly(vinyl chloride), colloquial: vinyl or polyvinyl; abbreviated: PVC) is the world's third-most widely produced synthetic polymer of plastic (after polyethylene and polypropylene). About 40 million tons of ...
. 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. Some is unsuitable for reuse. Much is captured in landfill
A landfill is a site for the disposal of waste materials. It is the oldest and most common form of waste disposal, although the systematic burial of waste with daily, intermediate and final covers only began in the 1940s. In the past, waste was ...
s or as plastic pollution
Plastic pollution is the accumulation of plastic objects and particles (e.g. plastic bottles, bags and microbeads) in the Earth's environment that adversely affects humans, wildlife and their habitat. Plastics that act as pollutants are catego ...
. Particular concern focuses on microplastics
Microplastics are "synthetic solid particles or polymeric matrices, with regular or irregular shape and with size ranging from 1 μm to 5 mm, of either primary or secondary manufacturing origin, which are insoluble in water." Microplastics a ...
. 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
Within industry, piping is a system of pipes used to convey fluids (liquids and gases) from one location to another. The engineering discipline of piping design studies the efficient transport of fluid.
Industrial process piping (and accomp ...
, plumbing
Plumbing is any system that conveys fluids for a wide range of applications. Plumbing uses piping, pipes, valves, piping and plumbing fitting, plumbing fixtures, Storage tank, tanks, and other apparatuses to convey fluids. HVAC, Heating and co ...
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 kg of plastic is produced annually per person, with production doubling every ten years.
The world's first fully synthetic plastic was Bakelite
Bakelite ( ), formally , is a thermosetting polymer, thermosetting phenol formaldehyde resin, formed from a condensation reaction of phenol with formaldehyde. The first plastic made from synthetic components, it was developed by Belgian chemist ...
, invented in New York in 1907, by Leo Baekeland
Leo Hendrik Baekeland ( , ; November 14, 1863 – February 23, 1944) was a Belgian chemist. Educated in Belgium and Germany, he spent most of his career in the United States. He is best known for the inventions of Velox photographic paper ...
, who coined the term "plastics". Dozens of different types of plastics are produced today, such as 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 bott ...
, which is widely used in product packaging, and polyvinyl chloride
Polyvinyl chloride (alternatively: poly(vinyl chloride), colloquial: vinyl or polyvinyl; abbreviated: PVC) is the world's third-most widely produced synthetic polymer of plastic (after polyethylene and polypropylene). About 40 million tons of ...
(PVC), used in construction and pipes because of its strength and durability. Many chemists have contributed to the materials science
Materials science is an interdisciplinary field of researching and discovering materials. Materials engineering is an engineering field of finding uses for materials in other fields and industries.
The intellectual origins of materials sci ...
of plastics, including Nobel laureate
The Nobel Prizes (, ) are awarded annually by the Royal Swedish Academy of Sciences, the Swedish Academy, the Karolinska Institutet, and the Norwegian Nobel Committee to individuals and organizations who make outstanding contributions in th ...
Hermann Staudinger, who has been called "the father of polymer chemistry
Polymer chemistry is a sub-discipline of chemistry that focuses on the structures, chemical synthesis, and chemical and physical properties of polymers and macromolecules. The principles and methods used within polymer chemistry are also applic ...
", and Herman Mark, known as "the father of polymer physics Polymer physics is the field of physics that studies polymers, their fluctuations, mechanical properties, as well as the kinetics of reactions involving degradation of polymers and polymerisation of monomers.P. Flory, ''Principles of Polymer Che ...
".
Etymology
The word ''plastic
Plastics are a wide range of synthetic polymers, synthetic or Semisynthesis, semisynthetic materials composed primarily of Polymer, polymers. Their defining characteristic, Plasticity (physics), plasticity, allows them to be Injection moulding ...
'' derives from the Ancient Greek
Ancient Greek (, ; ) includes the forms of the Greek language used in ancient Greece and the classical antiquity, ancient world from around 1500 BC to 300 BC. It is often roughly divided into the following periods: Mycenaean Greek (), 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
Petrochemicals (sometimes abbreviated as petchems) are the chemical products obtained from petroleum by refining. Some chemical compounds made from petroleum are also obtained from other fossil fuels, such as coal or natural gas, or renewable s ...
-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
Extrusion is a process used to create objects of a fixed cross section (geometry), cross-sectional profile by pushing material through a Die (manufacturing), die of the desired cross-section. Its two main advantages over other manufacturing pro ...
, or compression into a variety of shapes, including films, fibers, plates, tubes, bottles, and boxes, among many others. In materials science
Materials science is an interdisciplinary field of researching and discovering materials. Materials engineering is an engineering field of finding uses for materials in other fields and industries.
The intellectual origins of materials sci ...
, 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.
Structure
Most plastics contain organic polymers. The vast majority of these polymers are formed from chains of carbon atoms, with or without the attachment of oxygen, nitrogen or sulfur atoms. These chains comprise many repeating units formed from monomer
A monomer ( ; ''mono-'', "one" + '' -mer'', "part") is a molecule that can react together with other monomer molecules to form a larger polymer chain or two- or three-dimensional network in a process called polymerization.
Classification
Chemis ...
s. Each polymer chain consists of several thousand repeating units. The backbone is the part of the chain that is on the ''main path'', linking together a large number of repeat units. To customize the properties of a plastic, different molecular groups called side chains hang from this backbone; they are usually attached to the monomers before the monomers themselves are linked together to form the polymer chain. The structure of these side chains influences the properties of the polymer.
Classifications
Plastics are usually classified by the chemical structure of the polymer's backbone and side chains. Important groups classified in this way include the acrylics, polyester
Polyester is a category of polymers that contain one or two ester linkages in every repeat unit of their main chain. As a specific material, it most commonly refers to a type called polyethylene terephthalate (PET). Polyesters include some natura ...
s, silicones
In Organosilicon chemistry, organosilicon and polymer chemistry, a silicone or polysiloxane is a polymer composed of repeating units of siloxane (, where R = Organyl group, organic group). They are typically colorless oils or elastomer, rubber ...
, polyurethanes, and halogenated plastics. Plastics can be classified by the chemical process used in their synthesis, such as condensation
Condensation is the change of the state of matter from the gas phase into the liquid phase, and is the reverse of vaporization. The word most often refers to the water cycle. It can also be defined as the change in the state of water vapor ...
, polyaddition, and cross-link
In chemistry and biology, a cross-link is a bond or a short sequence of bonds that links one polymer chain to another. These links may take the form of covalent bonds or ionic bonds and the polymers can be either synthetic polymers or natural ...
ing. They can also be classified by their physical properties, including hardness
In materials science, hardness (antonym: softness) is a measure of the resistance to plastic deformation, such as an indentation (over an area) or a scratch (linear), induced mechanically either by Pressing (metalworking), pressing or abrasion ...
, density
Density (volumetric mass density or specific mass) is the ratio of a substance's mass to its volume. The symbol most often used for density is ''ρ'' (the lower case Greek letter rho), although the Latin letter ''D'' (or ''d'') can also be u ...
, tensile strength
Ultimate tensile strength (also called UTS, tensile strength, TS, ultimate strength or F_\text in notation) is the maximum stress that a material can withstand while being stretched or pulled before breaking. In brittle materials, the ultimate ...
, thermal resistance, and glass transition temperature
The glass–liquid transition, or glass transition, is the gradual and reversible transition in amorphous materials (or in amorphous regions within semicrystalline materials) from a hard and relatively brittle "glassy" state into a viscous or rub ...
. Plastics can additionally be classified by their resistance and reactions to various substances and processes, such as exposure to organic solvents, oxidation
Redox ( , , reduction–oxidation or oxidation–reduction) is a type of chemical reaction in which the oxidation states of the reactants change. Oxidation is the loss of electrons or an increase in the oxidation state, while reduction is ...
, and ionizing radiation
Ionizing (ionising) radiation, including Radioactive decay, nuclear radiation, consists of subatomic particles or electromagnetic waves that have enough energy per individual photon or particle to ionization, ionize atoms or molecules by detaching ...
. Other classifications of plastics are based on qualities relevant to manufacturing or product design for a particular purpose. Examples include thermoplastics
A thermoplastic, or thermosoftening plastic, is any plastic polymer material that becomes pliable or moldable at a certain elevated temperature and solidifies upon cooling.
Most thermoplastics have a high molecular weight. The polymer chains as ...
, thermosets, conductive polymers, biodegradable plastics, engineering plastic
Engineering plastics are a group of plastic materials that have better mechanical or thermal properties than the more widely used commodity plastics (such as polystyrene, polyvinyl chloride, polypropylene and polyethylene).
Engineering plastic ...
s and elastomer
An elastomer is a polymer with viscoelasticity (i.e. both viscosity and elasticity) and with weak intermolecular forces, generally low Young's modulus (E) and high failure strain compared with other materials. The term, a portmanteau of ''ela ...
s.
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
Polypropylene (PP), also known as polypropene, is a thermoplastic polymer used in a wide variety of applications. It is produced via chain-growth polymerization from the monomer Propene, propylene.
Polypropylene belongs to the group of polyolefin ...
(PP), polystyrene
Polystyrene (PS) is a synthetic polymer made from monomers of the aromatic hydrocarbon styrene. Polystyrene can be solid or foamed. General-purpose polystyrene is clear, hard, and brittle. It is an inexpensive resin per unit weight. It i ...
(PS), and polyvinyl chloride (PVC).
Thermosets, or thermosetting polymers, 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
Rubber, also called India rubber, latex, Amazonian rubber, ''caucho'', or ''caoutchouc'', as initially produced, consists of polymers of the organic compound isoprene, with minor impurities of other organic compounds.
Types of polyisoprene ...
is an example of this process. Before heating in the presence of sulfur, natural rubber (polyisoprene
Polyisoprene is, strictly speaking, a collective name for polymers that are produced by polymerization of isoprene. In practice polyisoprene is commonly used to refer to synthetic ''cis''-1,4-polyisoprene, made by the industrial polymerisation of ...
) is a sticky, slightly runny material, and after vulcanization, the product is dry and rigid.
:
Commodity, engineering, and high-performance plastics
Commodity plastics
Approximately 80% of global plastic production includes commodity plastics, a type of plastics primarily chosen for their low cost and ease of manufacturing. These plastics are mass-produced and used in everyday applications such as packaging, food containers, and household products. Most commodity plastics are identifiable by their Resin Identification Codes (RICs), a standardized numbering system developed by ASTM International
ASTM International, formerly known as American Society for Testing and Materials, is a standards organization that develops and publishes voluntary consensus technical international standards for a wide range of materials, products, systems and s ...
.
:
Polyethylene terephthalate
Polyethylene terephthalate (or poly(ethylene terephthalate), PET, PETE, or the obsolete PETP or PET-P), is the most common thermoplastic polymer resin of the polyester family and is used in synthetic fibre, fibres for clothing, packaging, conta ...
(PET or PETE)
:
High-density polyethylene
High-density polyethylene (HDPE) or polyethylene high-density (PEHD) is a thermoplastic polymer produced from the monomer ethylene. It is sometimes called "alkathene" or " polythene" when used for HDPE pipes. With a high strength-to-density rati ...
(HDPE or PE-HD)
:
Polyvinyl chloride
Polyvinyl chloride (alternatively: poly(vinyl chloride), colloquial: vinyl or polyvinyl; abbreviated: PVC) is the world's third-most widely produced synthetic polymer of plastic (after polyethylene and polypropylene). About 40 million tons of ...
(PVC or V)
:
Low-density polyethylene (LDPE or PE-LD),
:
Polypropylene
Polypropylene (PP), also known as polypropene, is a thermoplastic polymer used in a wide variety of applications. It is produced via chain-growth polymerization from the monomer Propene, propylene.
Polypropylene belongs to the group of polyolefin ...
(PP)
:
Polystyrene
Polystyrene (PS) is a synthetic polymer made from monomers of the aromatic hydrocarbon styrene. Polystyrene can be solid or foamed. General-purpose polystyrene is clear, hard, and brittle. It is an inexpensive resin per unit weight. It i ...
(PS)
Beyond the six most widely recognized listed above, there are more commodity plastics that are also mass-produced and commonly used, such as polyurethanes (PURs). PURs are a class of plastics also designated as commodity plastics due to their low cost, ease of manufacturing, and versatility. However, they lack RICs because they encompass many chemically diverse formulations such as foams and adhesives.
Packaging represents the largest application of commodity plastics, consuming 146 million metric tons (36% of global production) in 2015 alone. Beyond packaging, however, these plastics are critical in various other fields such as agriculture, construction, consumer goods, and healthcare.
Although many traits such as durability and resistance to biodegradability are desirable in various applications, they have led to significant environmental issues. An estimated 8 to 12 million tons of plastic enter oceans annually, primarily from mismanaged packaging waste. Commodity plastics account for the majority of this pollution, as their recycling rates remain low (e.g., only ~9% of all plastics are recycled globally). Microplastics derived from their degradation further threaten ecosystems and human health.
A huge number of plastics exist beyond the commodity plastics, with many having exceptional properties.
Engineering plastics
Engineering plastic
Engineering plastics are a group of plastic materials that have better mechanical or thermal properties than the more widely used commodity plastics (such as polystyrene, polyvinyl chloride, polypropylene and polyethylene).
Engineering plastic ...
s are more robust and are used to manufacture products such as vehicle parts, building and construction materials, and some machine parts. In some cases, they are polymer blend
In materials science, a polymer blend, or polymer mixture, is a member of a class of materials analogous to metal alloys, in which at least two polymers are blended together to create a new material with different physical properties.
History
Du ...
s formed by mixing different plastics together (ABS, HIPS etc.). Engineering plastics can replace metals in vehicles, lowering their weight and improving fuel efficiency by 6–8%. Roughly 50% of the volume of modern cars is made of plastic, but this only accounts for 12–17% of the vehicle weight.
* Acrylonitrile butadiene styrene (ABS): electronic equipment cases (e.g., computer monitors, printers, keyboards) and drainage pipes
* High-impact polystyrene (HIPS): refrigerator liners, food packaging, and vending cups
*Polycarbonate
Polycarbonates (PC) are a group of thermoplastic polymers containing carbonate ester, carbonate groups in their chemical structures. Polycarbonates used in engineering are strong, toughness, tough materials, and some grades are optically transp ...
(PC): compact discs, eyeglasses, riot shields, security windows, traffic lights, and lenses
*Polycarbonate + acrylonitrile butadiene styrene (PC + ABS): a blend of PC and ABS that creates a stronger plastic used in car interior and exterior parts, and in mobile phone bodies
*Polyethylene + acrylonitrile butadiene styrene (PE + ABS): a slippery blend of PE and ABS used in low-duty dry bearings
* Polymethyl methacrylate (PMMA) ( acrylic): contact lenses (of the original "hard" variety), glazing (best known in this form by its various trade names around the world; e.g. Perspex, Plexiglas, and Oroglas), fluorescent-light diffusers, and rear light covers for vehicles. It also forms the basis of artistic and commercial acrylic paints, when suspended in water with the use of other agents.
*Silicone
In Organosilicon chemistry, organosilicon and polymer chemistry, a silicone or polysiloxane is a polymer composed of repeating units of siloxane (, where R = Organyl group, organic group). They are typically colorless oils or elastomer, rubber ...
s (polysiloxanes): heat-resistant resins used mainly as sealants but also used for high-temperature cooking utensils and as a base resin for industrial paints
* Urea-formaldehyde (UF): one of the aminoplasts used as a multi-colorable alternative to phenolics: used as a wood adhesive (for plywood, chipboard, hardboard) and electrical switch housings
High-performance plastics
High-performance plastics are a category of polymers exhibiting superior properties compared to commodity and engineering plastics. These plastics can withstand high temperatures, often above 302°F (150°C), are highly resistant to chemical corrosion and degradation, have excellent mechanical and electric properties, and are lightweight and extremely versatile.
* Aramids: best known for their use in the manufacture of body armor
Body armour, personal armour (also spelled ''armor''), armoured suit (''armored'') or coat of armour, among others, is armour for human body, a person's body: protective clothing or close-fitting hands-free shields designed to absorb or deflect ...
, this class of heat-resistant and strong synthetic fibers also has applications in aerospace and military and includes Kevlar
Kevlar (para-aramid) is a strong, heat-resistant synthetic fiber, related to other aramids such as Nomex and Technora. Developed by Stephanie Kwolek at DuPont in 1965, the high-strength material was first used commercially in the early 1970s as ...
, Nomex, and Twaron.
*Ultra-high-molecular-weight polyethylene
Ultra-high-molecular-weight polyethylene (UHMWPE, UHMW) is a subset of the thermoplastic polyethylene. Also known as high-modulus polyethylene (HMPE), it has extremely long chains, with a molecular mass typically between 2 and 6 million amu. The l ...
s (UHMWPE)
* Polyetheretherketone (PEEK): strong, chemical- and heat-resistant thermoplastic; its biocompatibility allows for use in medical implant applications and aerospace moldings. It is one of the most expensive commercial polymers.
* Polyetherimide (PEI): a high-temperature, chemically stable polymer that does not crystallize
* Polyimide: a high-temperature plastic used in materials such as Kapton
file:Kaptonpads.jpg, Kapton insulating pads for mounting electronic parts on a heat sink
Kapton is a polyimide film used in flexible printed circuits (flexible electronics) and space blankets, which are used on spacecraft, satellites, and variou ...
tape
* Polysulfone (PS): high-temperature melt-processable resin used in membranes, filtration media, water heater dip tubes and other high-temperature applications
*Polytetrafluoroethylene
Polytetrafluoroethylene (PTFE) is a synthetic fluoropolymer of tetrafluoroethylene, and has numerous applications because it is chemically inert. The commonly known brand name of PTFE-based composition is Teflon by Chemours, a corporate spin-of ...
(PTFE): heat-resistant, low-friction coatings used in non-stick surfaces for frying pans, plumber's tape, and water slides
* Polyamide-imide (PAI): high-performance engineering plastic extensively used in high-performance gears, switches, transmissions, and other automotive components and aerospace parts
* Polyphenylene sulfide (PPS): extreme chemical resistance, flame retardancy, and thermal stability (up to 428°F).
* Polyethersulfone (PES): best known for their clarity, high-temperature resistance (up to 392°F), and biocompatibility. Commonly used in medical devices, food-grade equipment, and aerospace lighting.
* Polyvinylidene fluoride (PVDF): a nonreactive thermoplastic fluoropolymer known for extreme chemical resistance, ultraviolet stability, and piezoelectric
Piezoelectricity (, ) is the electric charge that accumulates in certain solid materials—such as crystals, certain ceramics, and biological matter such as bone, DNA, and various proteins—in response to applied stress (mechanics), mechanical s ...
properties. Commonly used in semiconductor tubing, lithium-ion battery binders, and architectural coatings.
* Liquid-crystal polymers (LCPs): a class of polymers combining the properties of both liquids and crystals, known for extreme dimensional stability, low thermal expansion, and high dielectric strength. Commonly used in miniature electronics, fiber-optic cables, and surgical devices.
* Polyimides (PIs): a class of high-performance thermosets, able to operate up to 572°F and best known for their excellent dielectric properties and radiation resistance. Commonly used in flexible printed circuits, space suit layers, and jet engine components.
* Polybenzimidazole (PBI): extremely high heat resistance (up to 752°F short-term), low outgassing, and flame resistance. Commonly used in firefighting gear, semiconductor tools, and aerospace thermal shields.
* Bismaleimide (BMI): known for its high glass transition temperature (around 482°F) and low moisture absorption. Commonly used in composite aircraft matrices and military radar systems.
* Cyanate esters: known for their low dielectric loss and space-grade radiation resistance. Commonly used in satellite components and radar antennas.
Amorphous and crystalline plastics
Many plastics are completely amorphous
In condensed matter physics and materials science, an amorphous solid (or non-crystalline solid) is a solid that lacks the long-range order that is a characteristic of a crystal. The terms "glass" and "glassy solid" are sometimes used synonymousl ...
, meaning they lack a highly ordered molecular structure. Crystalline
A crystal or crystalline solid is a solid material whose constituents (such as atoms, molecules, or ions) are arranged in a highly ordered microscopic structure, forming a crystal lattice that extends in all directions. In addition, macrosc ...
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
Intrinsically conducting polymers (ICPs) are organic polymers that conduct electricity. While a conductivity of up to 80 kilosiemens per centimeter (kS/cm) in stretch-oriented polyacetylene has been achieved, it does not approach that of most metals. For example, copper has a conductivity of several hundred kS/cm.
Biodegradable plastics and bioplastics
Biodegradable plastics
Biodegradable plastics are plastics that degrade (break down) upon exposure to biological factors, such as sunlight, ultra-violet radiation, moisture, bacteria, enzymes, or wind abrasion. Attacks by insects, such as waxworms and mealworms, can also be considered forms of biodegradation. Aerobic degradation requires the plastic to be exposed at the surface, whereas anaerobic degradation would be effective in landfill or composting systems. Some companies produce biodegradable additives to further promote biodegradation. Although starch powder can be added as a filler to facilitate degradation of some plastics, such treatment does not lead to complete breakdown. Some researchers have genetically engineered bacteria to synthesize completely biodegradable plastics, such as polyhydroxybutyrate
Polyhydroxybutyrate (PHB) is a Polyhydroxyalkanoates, polyhydroxyalkanoate (PHA), a polymer belonging to the polyesters class that are of interest as bio-derived and biodegradable plastics. The poly-3-hydroxybutyrate (P3HB) form of PHB is probabl ...
(PHB); however, these were still relatively expensive.
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
The Middle East (term originally coined in English language) is a geopolitical region encompassing the Arabian Peninsula, the Levant, Turkey, Egypt, Iran, and Iraq.
The term came into widespread usage by the United Kingdom and western Eur ...
and Russia
Russia, or the Russian Federation, is a country spanning Eastern Europe and North Asia. It is the list of countries and dependencies by area, largest country in the world, and extends across Time in Russia, eleven time zones, sharing Borders ...
produce most of the required petrochemical
Petrochemicals (sometimes abbreviated as petchems) are the chemical products obtained from petroleum by refining. Some chemical compounds made from petroleum are also obtained from other fossil fuels, such as coal or natural gas, or renewable s ...
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
Bratislava (German: ''Pressburg'', Hungarian: ''Pozsony'') is the Capital city, capital and largest city of the Slovakia, Slovak Republic and the fourth largest of all List of cities and towns on the river Danube, cities on the river Danube. ...
, 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
Azerbaijan, officially the Republic of Azerbaijan, is a Boundaries between the continents, transcontinental and landlocked country at the boundary of West Asia and Eastern Europe. It is a part of the South Caucasus region and is bounded by ...
Plastics are produced in chemical plants by the polymerization
In polymer chemistry, polymerization (American English), or polymerisation (British English), is a process of reacting monomer molecules together in a chemical reaction to form polymer chains or three-dimensional networks. There are many fo ...
of their starting materials (monomers
A monomer ( ; ''wikt:mono-, mono-'', "one" + ''wikt:-mer, -mer'', "part") is a molecule that can chemical reaction, react together with other monomer molecules to form a larger polymer chain or two- or three-dimensional network in a process called ...
); which are almost always petrochemical
Petrochemicals (sometimes abbreviated as petchems) are the chemical products obtained from petroleum by refining. Some chemical compounds made from petroleum are also obtained from other fossil fuels, such as coal or natural gas, or renewable s ...
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
In microeconomics, economies of scale are the cost advantages that enterprises obtain due to their scale of operation, and are typically measured by the amount of Productivity, output produced per unit of cost (production cost). A decrease in ...
. 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:
* Dow Chemical
* LyondellBasell
*ExxonMobil
Exxon Mobil Corporation ( ) is an American multinational List of oil exploration and production companies, oil and gas corporation headquartered in Spring, Texas, a suburb of Houston. Founded as the Successors of Standard Oil, largest direct s ...
* SABIC
*BASF
BASF SE (), an initialism of its original name , is a European Multinational corporation, multinational company and the List of largest chemical producers, largest chemical producer in the world. Its headquarters are located in Ludwigshafen, Ge ...
* Sibur
* Shin-Etsu Chemical
* Indorama Ventures
* Sinopec
* Braskem
Historically, Europe
Europe is a continent located entirely in the Northern Hemisphere and mostly in the Eastern Hemisphere. It is bordered by the Arctic Ocean to the north, the Atlantic Ocean to the west, the Mediterranean Sea to the south, and Asia to the east ...
and North America
North America is a continent in the Northern Hemisphere, Northern and Western Hemisphere, Western hemispheres. North America is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South Ameri ...
have dominated global plastics production. However, since 2010 Asia has emerged as a significant producer, with China
China, officially the People's Republic of China (PRC), is a country in East Asia. With population of China, a population exceeding 1.4 billion, it is the list of countries by population (United Nations), second-most populous country after ...
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 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
The European Union (EU) is a supranational union, supranational political union, political and economic union of Member state of the European Union, member states that are Geography of the European Union, located primarily in Europe. The u ...
(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 billion in revenue.
In 2017, the global plastics market was dominated by thermoplastic
A thermoplastic, or thermosoftening plastic, is any plastic polymer material that becomes pliable or moldable at a certain elevated temperature and solidifies upon cooling.
Most thermoplastics have a high molecular weight. The polymer chains as ...
s– polymers that can be melted and recast. Thermoplastics include 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 bott ...
(PE), polyethylene terephthalate
Polyethylene terephthalate (or poly(ethylene terephthalate), PET, PETE, or the obsolete PETP or PET-P), is the most common thermoplastic polymer resin of the polyester family and is used in synthetic fibre, fibres for clothing, packaging, conta ...
(PET), polypropylene
Polypropylene (PP), also known as polypropene, is a thermoplastic polymer used in a wide variety of applications. It is produced via chain-growth polymerization from the monomer Propene, propylene.
Polypropylene belongs to the group of polyolefin ...
(PP), polyvinyl chloride
Polyvinyl chloride (alternatively: poly(vinyl chloride), colloquial: vinyl or polyvinyl; abbreviated: PVC) is the world's third-most widely produced synthetic polymer of plastic (after polyethylene and polypropylene). About 40 million tons of ...
(PVC), polystyrene
Polystyrene (PS) is a synthetic polymer made from monomers of the aromatic hydrocarbon styrene. Polystyrene can be solid or foamed. General-purpose polystyrene is clear, hard, and brittle. It is an inexpensive resin per unit weight. It i ...
(PS) and synthetic fibers, which together represent 86% of all plastics.
Compounding
Plastic is not sold as a pure unadulterated substance, but is instead mixed with various chemicals and other materials, which are collectively known as additives. These are added during the compounding stage and include substances such as stabilizers, plasticizers and dye
Juan de Guillebon, better known by his stage name DyE, is a French musician. He is known for the music video of the single "Fantasy
Fantasy is a genre of speculative fiction that involves supernatural or Magic (supernatural), magical ele ...
s, which are intended to improve the lifespan, workability or appearance of the final item. In some cases, this can involve mixing different types of plastic together to form a polymer blend
In materials science, a polymer blend, or polymer mixture, is a member of a class of materials analogous to metal alloys, in which at least two polymers are blended together to create a new material with different physical properties.
History
Du ...
, 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
Blow molding (or moulding) is a manufacturing process for forming hollow plastic parts. It is also used for forming glass bottles or other hollow shapes.
In general, there are three main types of blow molding: extrusion blow molding, injection ...
: 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
Casting is a manufacturing process in which a liquid material is usually poured into a mold, which contains a hollow cavity of the desired shape, and then allowed to solidify. The solidified part is also known as a casting, which is ejected or ...
: 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
3D printing, or additive manufacturing, is the construction of a three-dimensional object from a CAD model or a digital 3D model. It can be done in a variety of processes in which material is deposited, joined or solidified under computer ...
: involves three-dimensionally printing an object layer by layer following a digital model using computer-aided design
Computer-aided design (CAD) is the use of computers (or ) to aid in the creation, modification, analysis, or optimization of a design. This software is used to increase the productivity of the designer, improve the quality of design, improve c ...
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 kg and 85 kg/capita/year, respectively). In China, there is lower per capita consumption (58 kg/capita/year), but high consumption nationally because of its large population.
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
Polypropylene (PP), also known as polypropene, is a thermoplastic polymer used in a wide variety of applications. It is produced via chain-growth polymerization from the monomer Propene, propylene.
Polypropylene belongs to the group of polyolefin ...
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
Polystyrene (PS) is a synthetic polymer made from monomers of the aromatic hydrocarbon styrene. Polystyrene can be solid or foamed. General-purpose polystyrene is clear, hard, and brittle. It is an inexpensive resin per unit weight. It i ...
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
Polyurethane foam is a solid polymeric foam based on polyurethane chemistry. As a specialist synthetic fibre, synthetic material with highly diverse applications, polyurethane foams are primarily used for thermal insulation and as a cushioning mat ...
Frying pan.jpeg, Non-stick
A non-stick surface is engineered to reduce the ability of other materials to stick to it. Non-sticking cookware is a common application, where the non-stick coating allows food to brown without sticking to the pan. Non-stick is often used to ref ...
cookware with Teflon coating
IPhone 5c blue back.jpg, iPhone 5c, a smartphone with a polycarbonate
Polycarbonates (PC) are a group of thermoplastic polymers containing carbonate ester, carbonate groups in their chemical structures. Polycarbonates used in engineering are strong, toughness, tough materials, and some grades are optically transp ...
"unibody" shell
KelpAquarium.jpg, To withstand the extreme water pressure
Pressure (symbol: ''p'' or ''P'') is the force applied perpendicular to the surface of an object per unit area over which that force is distributed. Gauge pressure (also spelled ''gage'' pressure)The preferred spelling varies by country and ev ...
, this deep Monterey Bay Aquarium
Monterey Bay Aquarium is a Nonprofit organization, nonprofit public aquarium in Monterey, California. Known for its regional focus on the marine habitats of Monterey Bay, it was the first to exhibit a living kelp forest when it opened in Octob ...
tank has windows made of acrylic glass up to 33 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
Polyvinyl chloride (alternatively: poly(vinyl chloride), colloquial: vinyl or polyvinyl; abbreviated: PVC) is the world's third-most widely produced synthetic polymer of plastic (after polyethylene and polypropylene). About 40 million tons of ...
(PVC), used widely for sanitary plumbing, can constitute up to 80% of the total volume. Unadulterated plastic (barefoot resin) is rarely sold.
Leaching
Additives may be weakly bound to the polymers or react in the polymer matrix. Although additives are blended into plastic they remain chemically distinct from it and can gradually leach back out during normal use, when in landfills, or following improper disposal in the environment. Additives may also degrade to form other compounds that could be more benign or more toxic. Plastic fragmentation into microplastics and nanoplastics can allow chemical additives to move in the environment far from the point of use. Once released, some additives and derivatives may persist in the environment and bioaccumulate in organisms. They can have adverse effects on human health and biota. A recent review by the United States Environmental Protection Agency (US EPA) revealed that out of 3,377 chemicals potentially associated with plastic packaging and 906 likely associated with it, 68 were ranked by ECHA as "highest for human health hazards" and 68 as "highest for environmental hazards".
Recycling
As additives change the properties of plastics they have to be considered during recycling. Presently, almost all recycling is performed by simply remelting and fabricating used plastic into new items. Additives present risks in recycled products due to their difficulty to remove. When plastic products are recycled, it is highly likely that the additives will be integrated into the new products. Plastic waste, even if it is all of the same polymer type, will contain varying types and amounts of additives. Mixing these together can give a material with inconsistent properties, which can be unappealing to industry. For example, mixing different colored plastics with different plastic colorants together can produce a discolored or brown material and for this reason plastic is usually sorted both by polymer type and color prior to recycling.
Lack of transparency and reporting across the value chain often results in lack of knowledge concerning the chemical profile of the final products. For example, products containing brominated flame retardants have been incorporated into new plastic products. Flame retardants are a group of chemicals used in electronic and electrical equipment, textiles, furniture and construction materials which should not be present in food packaging or child care products. A recent study found brominated dioxins as unintentional contaminants in toys made from recycled plastic electronic waste
Electronic waste (or e-waste) describes discarded electrical or electronics, electronic devices. It is also commonly known as waste electrical and electronic equipment (WEEE) or end-of-life (EOL) electronics. Used electronics which are destined ...
that contained brominated flame retardants. Brominated dioxins have been found to exhibit toxicity similar to that of chlorinated dioxins. They can have negative developmental effects and negative effects on the nervous system and interfere with mechanisms of the endocrine system.
Health effects
Plastics have proliferated in part because they are relatively benign. They are not acutely toxic, in large part because they are insoluble and or indigestible owing to their large molecular weight
A molecule is a group of two or more atoms that are held together by Force, attractive forces known as chemical bonds; depending on context, the term may or may not include ions that satisfy this criterion. In quantum physics, organic chemi ...
. Their degradation products also are rarely toxic. The same cannot be said about some additives, which tend to be lower molecular weight.
Controversies associated with plastics often relate to their additives, some of which are potentially harmful. For example, some flame retardants, such as octabromodiphenyl ether and pentabromodiphenyl ether, are unsuitable for food packaging. Other harmful additives include cadmium
Cadmium is a chemical element; it has chemical symbol, symbol Cd and atomic number 48. This soft, silvery-white metal is chemically similar to the two other stable metals in group 12 element, group 12, zinc and mercury (element), mercury. Like z ...
, chromium
Chromium is a chemical element; it has Symbol (chemistry), symbol Cr and atomic number 24. It is the first element in Group 6 element, group 6. It is a steely-grey, Luster (mineralogy), lustrous, hard, and brittle transition metal.
Chromium ...
, lead
Lead () is a chemical element; it has Chemical symbol, symbol Pb (from Latin ) and atomic number 82. It is a Heavy metal (elements), heavy metal that is density, denser than most common materials. Lead is Mohs scale, soft and Ductility, malleabl ...
and mercury (regulated under the Minamata Convention on Mercury), which have previously been used in plastic production, are banned in many jurisdictions. However, they are still routinely found in some plastic packaging, including for food.
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
Bisphenol A (BPA) is a chemical compound primarily used in the manufacturing of various plastics. It is a colourless solid which is Solubility, soluble in most common organic solvents, but has very poor solubility in water. BPA is produced on 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."
Types of additive
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 leachate
A leachate is any liquid that, in the course of passing through matter, extracts soluble or suspended solids, or any other component of the material through which it has passed.
Leachate is a widely used term in the environmental sciences wh ...
s, the EU has restricted the use of DEHP (di-2-ethylhexyl phthalate) and other phthalates in some applications, and the US has limited the use of DEHP, DPB, BBP, DINP, DIDP, and DnOP in children's toys and child-care articles through the Consumer Product Safety Improvement Act. Some compounds leaching from polystyrene food containers have been proposed to interfere with hormone functions and are suspected human carcinogens (cancer-causing substances). Other chemicals of potential concern include alkylphenols.[
While 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
The World Health Organization (WHO) is a list of specialized agencies of the United Nations, specialized agency of the United Nations which coordinates responses to international public health issues and emergencies. It is headquartered in Gen ...
's International Agency for Research on Cancer
The International Agency for Research on Cancer (IARC; ) is an intergovernmental agency forming part of the World Health Organization of the United Nations.
Its role is to conduct and coordinate research into the causes of cancer. It also cance ...
(IARC) has recognized vinyl chloride, the precursor to PVC, as a human carcinogen.
Bisphenol A (BPA)
Some plastic products degrade to chemicals with estrogen
Estrogen (also spelled oestrogen in British English; see spelling differences) is a category of sex hormone responsible for the development and regulation of the female reproductive system and secondary sex characteristics. There are three ...
ic activity. The primary building block of polycarbonates, bisphenol A
Bisphenol A (BPA) is a chemical compound primarily used in the manufacturing of various plastics. It is a colourless solid which is Solubility, soluble in most common organic solvents, but has very poor solubility in water. BPA is produced on 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 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
Because the chemical structure of most plastics renders them durable, they are resistant to many natural degradation processes. Much of this material may persist for centuries or longer, given the demonstrated persistence of structurally similar natural materials such as amber
Amber is fossilized tree resin. Examples of it have been appreciated for its color and natural beauty since the Neolithic times, and worked as a gemstone since antiquity."Amber" (2004). In Maxine N. Lurie and Marc Mappen (eds.) ''Encyclopedia ...
.
Estimates differ as to the amount of plastic waste
Plastic pollution is the accumulation of plastic objects and particles (e.g. plastic bottles, bags and microbeads) in the Earth's environment that adversely affects humans, wildlife and their habitat. Plastics that act as pollutants are cate ...
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 lasticsload into the sea."
The presence of plastics, particularly microplastics
Microplastics are "synthetic solid particles or polymeric matrices, with regular or irregular shape and with size ranging from 1 μm to 5 mm, of either primary or secondary manufacturing origin, which are insoluble in water." Microplastics a ...
, 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
The Montreal Protocol on Substances That Deplete the Ozone Layer is an international treaty designed to protect the ozone layer by phasing out the production of numerous substances that are responsible for ozone depletion. It was agreed on 16 ...
, CFCs had been commonly used in the manufacture of the plastic polystyrene, the production of which had contributed to depletion of the ozone layer
The ozone layer or ozone shield is a region of Earth's stratosphere that absorption (electromagnetic radiation), absorbs most of the Sun's ultraviolet radiation. It contains a high concentration of ozone (O3) in relation to other parts of the a ...
.
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.
Microplastics
Decomposition of plastics
Plastics degrade by a variety of processes, the most significant of which is usually photo-oxidation. Their chemical structure determines their fate. Polymers' marine degradation takes much longer as a result of the saline environment and cooling effect of the sea, contributing to the persistence of plastic debris in certain environments. Recent studies have shown, however, that plastics in the ocean decompose faster than had been previously thought, due to exposure to the sun, rain, and other environmental conditions, resulting in the release of toxic chemicals such as bisphenol A
Bisphenol A (BPA) is a chemical compound primarily used in the manufacturing of various plastics. It is a colourless solid which is Solubility, soluble in most common organic solvents, but has very poor solubility in water. BPA is produced on a ...
. However, due to the increased volume of plastics in the ocean, decomposition has slowed down. The Marine Conservancy has predicted the decomposition rates of several plastic products: It is estimated that a foam plastic cup will take 50 years, a plastic beverage holder will take 400 years, a disposable diaper will take 450 years, and fishing line will take 600 years to degrade.
Microbial species capable of degrading plastics are known to science, some of which are potentially useful for disposal of certain classes of plastic waste.
*In 1975, a team of Japanese scientists studying ponds containing waste water from a nylon factory discovered a strain of ''Flavobacterium
''Flavobacterium'' is a genus of Gram-negative, nonmotile and motile, rod-shaped bacteria that consists of 130 recognized species. Flavobacteria are found in soil and fresh water in a variety of environments. Several species are known to cause ...
'' that digests certain byproducts of nylon 6 manufacture, such as the linear dimer of 6-aminohexanoate. Nylon 4 (polybutyrolactam) can be degraded by the ND-10 and ND-11 strands of ''Pseudomonas sp.'' found in sludge, resulting in GABA (γ-aminobutyric acid) as a byproduct.
*Several species of soil fungi can consume polyurethane, including two species of the Ecuadorian fungus ''Pestalotiopsis
''Pestalotiopsis'' is a genus of ascomycete fungi in the Sporocadaceae family.
Taxonomy
The genus was circumscription (taxonomy), circumscribed by René Leopold Alix Ghislain Jules Steyaert in Bull. Jard. Bot. Etat. vol.19 on page 300 in 1949.
T ...
''. They can consume polyurethane both aerobically and anaerobically (such as at the bottom of landfills).
*Methanogenic microbial consortia degrade styrene, using it as a carbon source. '' Pseudomonas putida'' can convert styrene oil into various biodegradable plastic, biodegradable polyhydroxyalkanoates
Polyhydroxyalkanoates or PHAs are polyesters produced in nature by numerous microorganisms, including through bacterial fermentation of sugars or lipids. When produced by bacteria they serve as both a source of energy and as a carbon store. Mor ...
.
*Microbial communities isolated from soil samples mixed with starch have been shown to be capable of degrading polypropylene.
*The fungus '' Aspergillus fumigatus'' effectively degrades plasticized PVC. ''Phanerochaete chrysosporium
''Phanerochaete'' is a genus of crust fungi in the family Phanerochaetaceae.
Taxonomy
The genus was circumscription (taxonomy), circumscribed by Finnish mycologist Petter Karsten in 1889. Marinus Anton Donk redefined the limits of the genus in t ...
'' has been grown on PVC in a mineral salt agar. ''P. chrysosporium'', ''Lentinus tigrinus
''Lentinus tigrinus'' is a mushroom in the Polyporaceae family. It is classified as nonpoisonous. It has been reported that the mushrooms have significant antioxidant and antimicrobial activity.
The caps are wide. It produces a white spore pri ...
'', '' A. niger'', and '' A. sydowii'' can also effectively degrade PVC.
*Phenol-formaldehyde, commonly known as Bakelite, is degraded by the white rot fungus ''P. chrysosporium''.
*'' Acinetobacter'' has been found to partially degrade low-molecular-weight polyethylene oligomers. When used in combination, '' Pseudomonas fluorescens'' and '' Sphingomonas'' can degrade over 40% of the weight of plastic bags in less than three months. The thermophilic bacterium ''Brevibacillus borstelensis
''Brevibacillus borstelensis'' is a Gram-positive, aerobic, rod-shaped, endospore-forming bacterium of the genus ''Brevibacillus
''Brevibacillus'' is a genus of Gram-positive bacteria in the family Brevibacillaceae.
Phylogeny
The current ...
'' (strain 707) was isolated from a soil sample and found capable of using low-density 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 bott ...
as a sole carbon source when incubated at 50 °C. Pre-exposure of the plastic to ultraviolet radiation broke chemical bonds and aided biodegradation; the longer the period of UV exposure, the greater the promotion of the degradation.
*Hazardous molds have been found aboard space stations that degrade rubber into a digestible form.
*Several species of yeasts, bacteria, algae and lichens have been found growing on synthetic polymer artifacts in museums and at archaeological sites.
*In the plastic-polluted waters of the Sargasso Sea, bacteria have been found that consume various types of plastic; however, it is unknown to what extent these bacteria effectively clean up poisons rather than simply release them into the marine microbial ecosystem.
*Plastic-eating microbes also have been found in landfills.
*''Nocardia
''Nocardia'' is a genus of weakly staining Gram-positive, catalase, catalase-positive, rod-shaped bacteria. It forms partially acid-fast beaded branching filaments (appearing similar to fungi, but being truly bacteria). It contains a total of 8 ...
'' can degrade PET with an esterase enzyme.
*The fungus '' Geotrichum candidum'', found in Belize, has been found to consume the polycarbonate plastic found in CDs.
* Futuro houses are made of fiberglass-reinforced polyesters, polyester-polyurethane, and PMMA. One such house was found to be harmfully degraded by ''Cyanobacteria'' and ''Archaea''.
Recycling
Pyrolysis
By heating to above 500 °C (932 °F) in the absence of oxygen (pyrolysis
Pyrolysis is a process involving the Bond cleavage, separation of covalent bonds in organic matter by thermal decomposition within an Chemically inert, inert environment without oxygen. Etymology
The word ''pyrolysis'' is coined from the Gree ...
), plastics can be broken down into simpler hydrocarbon
In organic chemistry, a hydrocarbon is an organic compound consisting entirely of hydrogen and carbon. Hydrocarbons are examples of group 14 hydrides. Hydrocarbons are generally colourless and Hydrophobe, hydrophobic; their odor is usually fain ...
s, which can be used as feedstocks for the fabrication of new plastics. These hydrocarbons can also be used as fuels.
Greenhouse gas emissions
According to the Organisation for Economic Co-operation and Development
The Organisation for Economic Co-operation and Development (OECD; , OCDE) is an international organization, intergovernmental organization with 38 member countries, founded in 1961 to stimulate economic progress and international trade, wor ...
, plastic contributed greenhouse gas
Greenhouse gases (GHGs) are the gases in the atmosphere that raise the surface temperature of planets such as the Earth. Unlike other gases, greenhouse gases absorb the radiations that a planet emits, resulting in the greenhouse effect. T ...
es in the equivalent of 1.8 billion tons of carbon dioxide
Carbon dioxide is a chemical compound with the chemical formula . It is made up of molecules that each have one carbon atom covalent bond, covalently double bonded to two oxygen atoms. It is found in a gas state at room temperature and at norma ...
() to the atmosphere in 2019, 3.4% of global emissions. They say that by 2060, plastic could emit 4.3 billion tons of greenhouse gas a year. The effect of plastics on global warming is mixed. Plastics are generally made from fossil gas or petroleum; thus, the production of plastics creates further fugitive emissions of methane when the fossil gas or petroleum is produced. Additionally, much of the energy used in plastic production is not sustainable energy
Energy system, Energy is sustainability, sustainable if it "meets the needs of the present without compromising the ability of future generations to meet their own needs." Definitions of sustainable energy usually look at its effects on the e ...
; for example, high temperature from burning fossil gas. However, plastics can also limit methane emissions; for example, packaging to reduce food waste.
A study from 2024 found that compared to glass and aluminum, plastic may actually have less of a negative effect on the environment and therefore might be the best option for must food packaging and other common uses. The study found that, "replacing plastics with alternatives is worse for greenhouse gas emissions in most cases." and that the study involving European researchers found, "15 of the 16 applications a plastic product incurs fewer greenhouse gas emissions than their alternatives."
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 carcinogen
A carcinogen () is any agent that promotes the development of cancer. Carcinogens can include synthetic chemicals, naturally occurring substances, physical agents such as ionizing and non-ionizing radiation, and biologic agents such as viruse ...
ic polychlorinated dibenzo-p-dioxins. Open-air burning of plastic occurs at lower temperatures and normally releases such toxic
Toxicity is the degree to which a chemical substance or a particular mixture of substances can damage an organism. Toxicity can refer to the effect on a whole organism, such as an animal, bacterium, or plant, as well as the effect on a subst ...
fumes.
In the European Union
The European Union (EU) is a supranational union, supranational political union, political and economic union of Member state of the European Union, member states that are Geography of the European Union, located primarily in Europe. The u ...
, municipal waste incineration is regulated by the Industrial Emissions Directive, which stipulates a minimum temperature of 850 °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.
History
The development of plastics has evolved from the use of naturally plastic materials (e.g., gums
The gums or gingiva (: gingivae) consist of the mucosal tissue that lies over the mandible and maxilla inside the mouth. Gum health and disease can have an effect on general health.
Structure
The gums are part of the soft tissue lining of the ...
and shellac
Shellac () is a resin secreted by the female Kerria lacca, lac bug on trees in the forests of India and Thailand. Chemically, it is mainly composed of aleuritic acid, jalaric acid, shellolic acid, and other natural waxes. It is processed and s ...
) to the use of the chemical modification of those materials (e.g., natural rubber, cellulose
Cellulose is an organic compound with the chemical formula, formula , a polysaccharide consisting of a linear chain of several hundred to many thousands of glycosidic bond, β(1→4) linked glucose, D-glucose units. Cellulose is an important s ...
, collagen
Collagen () is the main structural protein in the extracellular matrix of the connective tissues of many animals. It is the most abundant protein in mammals, making up 25% to 35% of protein content. Amino acids are bound together to form a trip ...
, 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
In the history of Europe, the Middle Ages or medieval period lasted approximately from the 5th to the late 15th centuries, similarly to the post-classical period of global history. It began with the fall of the Western Roman Empire and ...
. 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
The Industrial Revolution, sometimes divided into the First Industrial Revolution and Second Industrial Revolution, was a transitional period of the global economy toward more widespread, efficient and stable manufacturing processes, succee ...
, 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
Nitric acid is an inorganic compound with the formula . It is a highly corrosive mineral acid. The compound is colorless, but samples tend to acquire a yellow cast over time due to decomposition into nitrogen oxide, oxides of nitrogen. Most com ...
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
The International Exhibition of 1862, officially the London International Exhibition of Industry and Art, also known as the Great London Exposition, was a world's fair held from 1 May to 1 November 1862 in South Kensington, London, England. Th ...
in London and garnered for Parkes the bronze medal.
In 1893, French chemist Auguste Trillat discovered the means to insolubilize casein
Casein ( , from Latin ''caseus'' "cheese") is a family of related phosphoproteins (CSN1S1, αS1, aS2, CSN2, β, K-casein, κ) that are commonly found in mammalian milk, comprising about 80% of the proteins in cow's milk and between 20% and 60% of ...
(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
Bakelite ( ), formally , is a thermosetting polymer, thermosetting phenol formaldehyde resin, formed from a condensation reaction of phenol with formaldehyde. The first plastic made from synthetic components, it was developed by Belgian chemist ...
, invented in New York in 1907 by Leo Baekeland
Leo Hendrik Baekeland ( , ; November 14, 1863 – February 23, 1944) was a Belgian chemist. Educated in Belgium and Germany, he spent most of his career in the United States. He is best known for the inventions of Velox photographic paper ...
, who coined the term ''plastics''. Many chemists have contributed to the materials science
Materials science is an interdisciplinary field of researching and discovering materials. Materials engineering is an engineering field of finding uses for materials in other fields and industries.
The intellectual origins of materials sci ...
of plastics, including Nobel laureate Hermann Staudinger, who has been called "the father of polymer chemistry
Polymer chemistry is a sub-discipline of chemistry that focuses on the structures, chemical synthesis, and chemical and physical properties of polymers and macromolecules. The principles and methods used within polymer chemistry are also applic ...
", and Herman Mark, known as "the father of polymer physics Polymer physics is the field of physics that studies polymers, their fluctuations, mechanical properties, as well as the kinetics of reactions involving degradation of polymers and polymerisation of monomers.P. Flory, ''Principles of Polymer Che ...
". 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
BASF SE (), an initialism of its original name , is a European Multinational corporation, multinational company and the List of largest chemical producers, largest chemical producer in the world. Its headquarters are located in Ludwigshafen, Ge ...
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
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 bott ...
was discovered by Imperial Chemical Industries
Imperial Chemical Industries (ICI) was a British Chemical industry, chemical company. It was, for much of its history, the largest manufacturer in Britain. Its headquarters were at Millbank in London. ICI was listed on the London Stock Exchange ...
(ICI) researchers Reginald Gibson and Eric Fawcett.
The discovery of polyethylene terephthalate
Polyethylene terephthalate (or poly(ethylene terephthalate), PET, PETE, or the obsolete PETP or PET-P), is the most common thermoplastic polymer resin of the polyester family and is used in synthetic fibre, fibres for clothing, packaging, conta ...
(PETE) is credited to employees of the Calico Printers' Association
The Calico Printers' Association Ltd was a British textile company founded in 1899, from the amalgamation of 46 textile printing companies and 13 textile merchants. The industry had prospered in the latter half of the 19th century but the fierc ...
in the UK in 1941; it was licensed to DuPont
Dupont, DuPont, Du Pont, duPont, or du Pont may refer to:
People
* Dupont (surname) Dupont, also spelled as DuPont, duPont, Du Pont, or du Pont is a French surname meaning "of the bridge", historically indicating that the holder of the surname re ...
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
Polypropylene (PP), also known as polypropene, is a thermoplastic polymer used in a wide variety of applications. It is produced via chain-growth polymerization from the monomer Propene, propylene.
Polypropylene belongs to the group of polyolefin ...
was discovered by Giulio Natta and began to be manufactured in 1957. Also in 1954 expanded polystyrene
Polystyrene (PS) is a synthetic polymer made from monomers of the aromatic hydrocarbon styrene. Polystyrene can be solid or foamed. General-purpose polystyrene is clear, hard, and brittle. It is an inexpensive resin per unit weight. It i ...
(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.
Policy
Work is currently underway to develop a global treaty on plastic pollution. On March 2, 2022, UN Member States voted at the resumed fifth UN Environment Assembly (UNEA-5.2) to establish an Intergovernmental Negotiating Committee (INC) with the mandate of advancing a legally-binding international agreement on plastics. The resolution is entitled "End plastic pollution: Towards an international legally binding instrument." The mandate specifies that the INC must begin its work by the end of 2022 with the goal of "completing a draft global legally binding agreement by the end of 2024."
See also
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Plastic in the sense of malleable
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References
* ''Substantial parts of this text originated from'' ''by Greg Goebel (March 1, 2001), which is in the public domain''.
Sources
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Dielectrics
Articles containing video clips