Biodegradable plastic
Biodegradable plastics are plastics that can be decomposed by the action of living organisms, usually bacteria.[1]
Plastic
An early success in the recycling of plastics is Vinyloop, an industrial process to separate PVC from other materials through dissolution, filtration and separation of contaminants. A solvent is used in a closed loop to elute PVC from the waste. This makes it possible to recycle composite PVC waste, which is normally incinerated or put in a landfill. Vinyloop-based recycled PVC's primary energy demand is 46 percent lower than conventionally produced PVC. The global warming potential is 39 percent lower. This is why the use of recycled material leads to a significantly better ecological outcome. This process was used after the Olympic Games in London 2012. Parts of temporary Buildings like the Water Polo Arena and the Royal Artillery Barracks were recycled. In this way, the PVC Policy could be fulfilled, which says that no PVC waste should be left after the games had ended. Biodegradable polythene film
If disposed of in a sanitary landfill, most traditional plastics do not readily decompose. The sterile conditions of a sealed landfill also deter degradation of biodegradable polymers. Plastisphere
Plastic pollution provides a more durable "ship" than biodegradable material for carrying the organisms over long distances. This long distance transportation can move microbes to different ecosystems and potentially introduce invasive species as well as harmful algae. The microorganisms found on the plastic debris include autotrophs, heterotrophs and symbionts. The ecosystem created by the plastisphere differs from other floating materials that naturally occur (i.e., feathers and algae) due to the slow speed of biodegradation and other different conditions. Decomposition
Decomposition is the process by which organic substances are broken down into a more simple organic matter. The process is a part of the nutrient cycle and is essential for recycling the finite matter that occupies physical space in the biosphere. Bodies of living organisms begin to decompose shortly after death. Animals, such as worms, also help decompose the organic materials. Organisms that do this are known as decomposers. Although no two organisms decompose in the same way, they all undergo the same sequential stages of decomposition. The science which studies decomposition is generally referred to as "taphonomy" from the Greek word "taphos", meaning tomb. Great Pacific garbage patch
Disintegration means that much of the plastic is too small to be seen. In a 2001 study, researchers[10] found concentrations of plastic particles at 334,721 pieces per km2 with a mean mass of 5.1kg (11.3lbs) per km2, in the neuston. The overall concentration of plastics was seven times greater than the concentration of zooplankton in many of the sampled areas. Samples collected deeper in the water column found much lower concentrations of plastic particles (primarily monofilament fishing line pieces).[49] Plasticity (physics)
Perfect plasticity is a property of materials to undergo irreversible deformation without any increase in stresses or loads. Plastic materials with hardening necessitate increasingly higher stresses to result in further plastic deformation. Generally, plastic deformation is also dependent on the deformation speed, i.e. higher stresses usually have to be applied to increase the rate of deformation. Such materials are said to deform visco-plastically. Conservation and restoration of plastic objects
These are plastics that are still capable of degradation but its effects are not as harmful to nearby objects.The list below is of chemical compositions that make up common plastics found in museum collections: Ceramic
These materials do show plastic deformation. However, because of the rigid structure of the crystalline materials, there are very few available slip systems for dislocations to move, and so they deform very slowly. With the non-crystalline (glassy) materials, viscous flow is the dominant source of plastic deformation, and is also very slow. It is therefore neglected in many applications of ceramic materials. Microplastics
Approximately half of the plastic material introduced to the marine environment is buoyant, but fouling by organisms can cause plastic debris to sink to the sea floor, where it may interfere with sediment-dwelling species and sedimental gas exchange processes. Several factors contribute to microplastic’s buoyancy, including the density of the plastic it is composed as well as the size and shape of the microplastic fragments themselves. Microplastics can also form a buoyant biofilm layer on the ocean’s surface. Buoyancy changes in relation to ingestion of microplastics have been clearly observed in autotrophs because the absorption can interfere with photosynthesis and subsequent gas levels. However, this issue is of more importance for larger plastic debris. OXO-biodegradation
In relation to littering, the report found that although it appeared the oxo-degradable plastics industry could create products with minimal toxic impact on flora and fauna, it had not been conclusively proven that there were no negative effects. Marketing oxo-degradables as a solution for plastic waste in the environment may make it more likely items are discarded inappropriately and in marine environments, the fragmentation process made oxo-degradable plastic less likely to be recovered during clean-up exercises. Polymer degradation
Today there are primarily seven commodity polymers in use: polyethylene, polypropylene, polyvinyl chloride, polyethylene terephthalate (PET, PETE), polystyrene, polycarbonate, and poly(methyl methacrylate) (Plexiglas). These make up nearly 98% of all polymers and plastics encountered in daily life. Each of these polymers has its own characteristic modes of degradation and resistances to heat, light and chemicals. Polyethylene, polypropylene, and poly(methyl methacrylate) are sensitive to oxidation and UV radiation, while PVC may discolor at high temperatures due to loss of hydrogen chloride gas, and become very brittle. PET is sensitive to hydrolysis and attack by strong acids, while polycarbonate depolymerizes rapidly when exposed to strong alkalis. Great Pacific garbage patch
The patch is one of several oceanic regions where researchers have studied the effects and impact of plastic photodegradation in the neustonic layer of water.[46] Unlike organic debris, which biodegrades, plastic disintegrates into ever smaller pieces while remaining a polymer (without changing chemically). This process continues down to the molecular level.[47] Some plastics decompose within a year of entering the water, releasing potentially toxic chemicals such as bisphenol A, PCBs and derivatives of polystyrene.[48] As the plastic flotsam photodegrades into smaller and smaller pieces, it concentrates in the upper water column. As it disintegrates, the pieces become small enough to be ingested by aquatic organisms that reside near the ocean's surface. Plastic may become concentrated in neuston, thereby entering the food chain. Plastic pollution
Plastic debris is categorized as either primary or secondary. Primary plastics are in their original form when collected. Examples of these would be bottle caps, cigarette butts, and microbeads. Secondary plastics, on the other hand, account for smaller plastics that have resulted from the degradation of primary plastics. Productivity improving technologies
Dematerialization is made possible by substitution with better materials and by engineering to reduce weight while maintaining function. Modern examples are plastic beverage containers replacing glass and paperboard, plastic shrink wrap used in shipping and light weight plastic packing materials. Dematerialization has been occurring in the U. S. steel industry where the peak in consumption occurred in 1973 on both an absolute and per capita basis. At the same time, per capita steel consumption grew globally through outsourcing. Cumulative global GDP or wealth has grown in direct proportion to energy consumption since 1970, while Jevons paradox posits that efficiency improvement leads to increased energy consumption. Access to energy globally constrains dematerialization. Bin bag
Oxo-biodegradable plastic bags have the same strength as ordinary plastic and cost very little extra. They will degrade then biodegrade if they get into the open environment, but they can be recycled if collected during their useful life. They are designed so that they will not degrade deep in landfill and will not therefore generate methane. Oxo-biodegradable plastic does not degrade quickly in low temperature "windrow" composting, but it is suitable for "in-vessel" composting at the higher temperatures required by the animal by-products regulations. Oxo-biodegradable plastic is bio-assimilated by the same bacteria and fungi, which transform natural material such as twigs and leaves to cell biomass, like lignocellulosic materials. Oxo-biodegradable plastic is designed to degrade initially by a process which includes both photo-oxidation and thermo-oxidation, so it can degrade in the dark. Resin identification code 7 is applicable to biodegradable plastics. Plasticity (physics)
If the stress exceeds a critical value, as was mentioned above, the material will undergo plastic, or irreversible, deformation. This critical stress can be tensile or compressive. The Tresca and the von Mises criteria are commonly used to determine whether a material has yielded. However, these criteria have proved inadequate for a large range of materials and several other yield criteria are also in widespread use. Plastic pollution
Although biodegradable and degradable plastics have helped reduce plastic pollution, there are some drawbacks. One issue concerning both types of plastics is that they do not break down very efficiently in natural environments. There, degradable plastics that are oil-based may break down into smaller fractions, at which point they do not degrade further. Oceanic carbon cycle
POC is decomposed by a series of microbe-driven processes, such as methanogenesis and sulfate reduction, before burial in the seafloor. Degradation of POC also results in microbial methane production which is the main gas hydrate on the continental margins. Lignin and pollen are inherently resistant to degradation, and some studies show that inorganic matrices may also protect organic matter. Preservation rates of organic matter depend on other interdependent variables that vary nonlinearly in time and space. Although organic matter breakdown occurs rapidly in the presence of oxygen, microbes utilizing a variety of chemical species (via redox gradients) can degrade organic matter in anoxic sediments. The burial depth at which degradation halts depends upon the sedimentation rate, the relative abundance of organic matter in the sediment, the type of organic matter being buried, and innumerable other variables. While decomposition of organic matter can occur in anoxic sediments when bacteria use oxidants other than oxygen (nitrate, sulfate, Fe), decomposition tends to end short of complete mineralization. This occurs because of preferential decomposition of labile molecules over refractile molecules. Biopolymer
Some plastics are now referred to as being 'degradable', 'oxy-degradable' or 'UV-degradable'. This means that they break down when exposed to light or air, but these plastics are still primarily (as much as 98 per cent) oil-based and are not currently certified as 'biodegradable' under the European Union directive on Packaging and Packaging Waste (94/62/EC). Biopolymers will break down, and some are suitable for domestic composting. Marine debris
Eighty percent of marine debris is plastic. Plastics accumulate because they typically do not biodegrade as many other substances do. They photodegrade on exposure to sunlight, although they do so only under dry conditions, as water inhibits photolysis. In a 2014 study using computer models, scientists from the group 5 Gyres, estimated 5.25 trillion pieces of plastic weighing 269,000 tons were dispersed in oceans in similar amount in the Northern and Southern Hemispheres, and one-hundredth of them are particles the scale of a sand. Plastic pollution
Plastic pollution is the accumulation of plastic objects (e.g.: plastic bottles and much more) in the Earth's environment that adversely affects wildlife, wildlife habitat and humans. Plastics that act as pollutants are categorized into micro-, meso-, or macro debris, based on size. Plastics are inexpensive and durable, and as a result levels of plastic production by humans are high. Moreover, the chemical structure of most plastics renders them resistant to many natural processes of degradation and as a result they are slow to degrade. Together, these two factors have led to a high prominence of plastic pollution in the environment. Environmental impact of agriculture
In addition to the increased runoff that results from plasticulture, there is also the problem of the increased amount of waste form the plastic mulch itself. The use of plastic mulch for vegetables, strawberries, and other row and orchard crops exceeds 110 million pounds annually in the United States. Most plastic ends up in the landfill, although there are other disposal options such as disking mulches into the soil, on-site burying, on-site storage, reuse, recycling, and incineration. The incineration and recycling options are complicated by the variety of the types of plastics that are used and by the geographic dispersal of the plastics. Plastics also contain stabilizers and dyes as well as heavy metals, which limits the amount of products that can be recycled. Research is continually being conducted on creating biodegradable or photodegradable mulches. While there has been minor success with this, there is also the problem of how long the plastic takes to degrade, as many biodegradable products take a long time to break down. Deformation (engineering)
This type of deformation is also irreversible. A break occurs after the material has reached the end of the elastic, and then plastic, deformation ranges. At this point forces accumulate until they are sufficient to cause a fracture. All materials will eventually fracture, if sufficient forces are applied. Polymer degradation
Polymer degradation by galvanic action was first described in the technical literature in 1990. This was the discovery that "plastics can corrode", i.e. polymer degradation may occur through galvanic action similar to that of metals under certain conditions and has been referred to as the "Faudree Effect". In the aerospace field, this finding has largely contributed to aircraft safety, mainly those aircraft that use CFRP and has resulted in a wide body of follow-up research and patents. Normally, when two dissimilar metals such as copper (Cu) and iron (Fe) are put into contact and then immersed in salt water, the iron will undergo corrosion, or rust. This is called a galvanic circuit where the copper is the noble metal and the iron is the active metal, i.e., the copper is the positive (+) electrode and the iron is the negative (-) electrode. A battery is formed. It follows that plastics are made stronger by impregnating them with thin carbon fibers only a few micrometers in diameter known as carbon fiber reinforced polymers (CFRP). This is to produce materials that are high strength and resistant to high temperatures. The carbon fibers act as a noble metal similar to gold (Au) or platinum (Pt). When put into contact with a more active metal, for example with aluminum (Al) in salt water the aluminum corrodes. However, in early 1990, it was reported that imide-linked resins in CFRP composites degrade when bare composite is coupled with an active metal in salt water environments. This is because corrosion not only occurs at the aluminum anode, but also at the carbon fiber cathode in the form of a very strong base with a pH of about 13. This strong base reacts with the polymer chain structure degrading the polymer. Polymers affected include bismaleimides (BMI), condensation polyimides, triazines, and blends thereof. Degradation occurs in the form of dissolved resin and loose fibers. The hydroxyl ions generated at the graphite cathode attack the O-C-N bond in the polyimide structure. Standard corrosion protection procedures were found to prevent polymer degradation under most conditions. Biodegradation
Plastics biodegrade at highly variable rates. PVC-based plumbing is selected for handling sewage because PVC resists biodegradation. Some packaging materials on the other hand are being developed that would degrade readily upon exposure to the environment. Examples of synthetic polymers that biodegrade quickly include polycaprolactone, other polyesters and aromatic-aliphatic esters, due to their ester bonds being susceptible to attack by water. A prominent example is poly-3-hydroxybutyrate, the renewably derived polylactic acid, and the synthetic polycaprolactone. Others are the cellulose-based cellulose acetate and celluloid (cellulose nitrate).
Under low oxygen conditions plastics break down more slowly. The breakdown process can be accelerated in specially designed compost heap. Starch-based plastics will degrade within two to four months in a home compost bin, while polylactic acid is largely undecomposed, requiring higher temperatures. Polycaprolactone and polycaprolactone-starch composites decompose slower, but the starch content accelerates decomposition by leaving behind a porous, high surface area polycaprolactone. Nevertheless, it takes many months.
In 2016, a bacterium named "Ideonella sakaiensis" was found to biodegrade PET. Superplasticity
In materials science, superplasticity is a state in which solid crystalline material is deformed well beyond its usual breaking point, usually over about 200% during tensile deformation. Such a state is usually achieved at high homologous temperature. Examples of superplastic materials are some fine-grained metals and ceramics. Other non-crystalline materials (amorphous) such as silica glass ("molten glass") and polymers also deform similarly, but are not called superplastic, because they are not crystalline; rather, their deformation is often described as Newtonian fluid. Superplastically deformed material gets thinner in a very uniform manner, rather than forming a "neck" (a local narrowing) that leads to fracture. Also, the formation of microvoids, which is another cause of early fracture, is inhibited. Ecosystem
The carbon and nutrients in dead organic matter are broken down by a group of processes known as decomposition. This releases nutrients that can then be re-used for plant and microbial production and returns carbon dioxide to the atmosphere (or water) where it can be used for photosynthesis. In the absence of decomposition, the dead organic matter would accumulate in an ecosystem, and nutrients and atmospheric carbon dioxide would be depleted.[17] Approximately 90% of terrestrial net primary production goes directly from plant to decomposer.[16] PETase
The first PETase enzyme was discovered in 2016 from "Ideonella sakaiensis" strain 201-F6 bacteria found from sludge samples collected close to a Japanese PET bottle recycling site. Scientists suggested that the PETase enzyme may have had past enzymatic activity associated with degradation of a waxy coating on plants. Normally the natural degradation of PET without PETase will take hundred of years. PET (polyethylene terephthalate-plastics)is a very common source of many plastic items used in the daily life. PETase can degrade PET in a way that is not harmful to the environment. Other types of PET degrading hydolases have been known before this discovery. These include hydrolases such as: lipases, esterases, and cutinases. Discoveries of polyester degrading enzymes date at least as far back as 1975 (α-chymotrypsin) and 1977 (lipase) for example. PET plastic was put into widespread use in the 1970s and it has been suggested that PETases in bacteria evolved only recently. Dislocation
In 1934, Egon Orowan, Michael Polanyi and G. I. Taylor, almost simultaneously realized that plastic deformation could be explained in terms of the theory of dislocations. Dislocations can move if the atoms from one of the surrounding planes break their bonds and rebond with the atoms at the terminating edge. In effect, a half plane of atoms is moved in response to shear stress by breaking and reforming a line of bonds, one (or a few) at a time. The energy required to break a single bond is far less than that required to break all the bonds on an entire plane of atoms at once. Even this simple model of the force required to move a dislocation shows that plasticity is possible at much lower stresses than in a perfect crystal. In many materials, particularly ductile materials, dislocations are the "carrier" of plastic deformation, and the energy required to move them is less than the energy required to fracture the material. Dislocations give rise to the characteristic malleability of metals. Biodegradable plastic
There are allegations that biodegradable plastic bags may release metals, and may require a great deal of time to degrade in certain circumstances [10] and that OBD (oxo-biodegradable) plastics may produce tiny fragments of plastic that do not continue to degrade at any appreciable rate regardless of the environment.[11][12] The response of the Oxo-biodegradable Plastics Association (www.biodeg.org) is that OBD plastics do not contain metals. They contain salts of metals, which are not prohibited by legislation and are in fact necessary as trace-elements in the human diet. Oxo-biodegradation of polymer material has been studied in depth at the Technical Research Institute of Sweden and the Swedish University of Agricultural Sciences. A peer-reviewed report of the work shows 91% biodegradation in a soil environment within 24 months, when tested in accordance with ISO 17556.[13] Plastic recycling
When different types of plastics are melted together, they tend to phase-separate, like oil and water, and set in these layers. The phase boundaries cause structural weakness in the resulting material, meaning that polymer blends are useful in only limited applications. The 2 most widely manufactured plastics, polypropylene and polyethylene, behave this way, which limits their utility for recycling. Recently, the use of block copolymers as "molecular stitches" or "macromolecular welding flux" has been proposed to overcome the difficulties associated with phase separation during recycling. Deformation (engineering)
Under tensile stress, plastic deformation is characterized by a strain hardening region and a necking region and finally, fracture (also called rupture). During strain hardening the material becomes stronger through the movement of atomic dislocations. The necking phase is indicated by a reduction in cross-sectional area of the specimen. Necking begins after the ultimate strength is reached. During necking, the material can no longer withstand the maximum stress and the strain in the specimen rapidly increases. Plastic deformation ends with the fracture of the material. Nutrient cycle
In contrast to the planets natural ecosystems, technology (or technoecosystems) is not reducing its impact on planetary resources. Only 7% of total plastic waste (adding up to millions upon millions of tons) is being recycled by industrial systems; the 93% that never makes it into the industrial recycling stream is presumably "absorbed" by natural recycling systems In contrast and over extensive lengths of time (billions of years) ecosystems have maintained a consistent balance with production roughly equaling respiratory consumption rates. The balanced recycling efficiency of nature means that production of decaying waste material has exceeded rates of recyclable consumption into food chains equal to the global stocks of fossilized fuels that escaped the chain of decomposition. OXO-biodegradation
The Commission found there was no conclusive evidence that, in the open environment, oxo-degradables fragmented to a sufficiently low molecular weight to enable biodegradation. There was no conclusive evidence about the time needed for oxo-degradable plastics to fragment in marine environments, nor about the degree of fragmentation. It said there was a considerable risk that fragmented plastics would not fully biodegrade, leading to a subsequent risk of an accelerated and accumulating amount of microplastics, especially in the marine environment. Rapid fragmentation increased the risk of microplastic ingestion by marine animals. Sea
Much floating plastic rubbish does not biodegrade, instead disintegrating over time and eventually breaking down to the molecular level. Rigid plastics may float for years. In the centre of the Pacific gyre there is a permanent floating accumulation of mostly plastic waste and there is a similar garbage patch in the Atlantic. Foraging sea birds such as the albatross and petrel may mistake debris for food, and accumulate indigestible plastic in their digestive systems. Turtles and whales have been found with plastic bags and fishing line in their stomachs. Microplastics may sink, threatening filter feeders on the seabed. Plastic
Plastics can be pyrolyzed into hydrocarbon fuels, since plastics include hydrogen and carbon. One kilogram of waste plastic produces roughly a liter of hydrocarbon. Plastic pollution
There are also other types of degradable materials that are not considered to be biopolymers, because they are oil-based, similar to other conventional plastics. These plastics are made to be more degradable through the use of different additives, which help them degrade when exposed to UV rays or other physical stressors. yet, biodegradation-promoting additives for polymers have been shown not to significantly increase biodegradation. Welding
Plastics are generally divided into two categories, which are "thermosets" and "thermoplastics." A thermoset is a plastic in which a chemical reaction sets the molecular bonds after first forming the plastic, and then the bonds cannot be broken again without degrading the plastic. Thermosets cannot be melted, therefore, once a thermoset has set it is impossible to weld it. Examples of thermosets include epoxies, silicone, vulcanized rubber, polyester, and polyurethane. Plastic-coated paper
Plastic coatings or layers usually make paper recycling more difficult. Some plastic laminations can be separated from the paper during the recycling process, allowing filtering out the film. If the coated paper is shredded prior to recycling, the degree of separation depends on the particular process. Some plastic coatings are water dispersible to aid recycling and repulping. Special recycling processes are available to help separate plastics. Some plastic coated papers are incinerated for heat or landfilled rather than recycled. Plastic
The greatest challenge to the recycling of plastics is the difficulty of automating the sorting of plastic wastes, making it labor-intensive. Typically, workers sort the plastic by looking at the resin identification code, although common containers like soda bottles can be sorted from memory. Typically, the caps for PETE bottles are made from a different kind of plastic which is not recyclable, which presents additional problems for the sorting process. Other recyclable materials such as metals are easier to process mechanically. However, new processes of mechanical sorting are being developed to increase the capacity and efficiency of plastic recycling. Biodegradation
It’s important to note factors that effect biodegradation rates during product testing to ensure that the results produced are accurate and reliable. Several materials will test as being biodegradable under optimal conditions in a lab for approval but these results may not reflect real world outcomes where factors are more variable. For example, a material may have tested as biodegrading at a high rate in the lab may not degrade at a high rate in a landfill because landfills often lack light, water, and microbial activity that are necessary for degradation to occur. Thus, it is very important that there are standards for plastic biodegradable products, which have a large impact on the environment. The development and use of accurate standard test methods can help ensure that all plastics that are being produced and commercialized will actually biodegrade in natural environments. One test that has been developed for this purpose is DINV 54900. South Pacific garbage patch
As the plastic particles are primarily found in the pelagic layer of the ocean they experience high levels of Photodegradation, which causes the plastics to break down into ever smaller pieces. These pieces eventually become so small that even microorganisms can ingest and metabolize them converting these plastics into carbon dioxide. In some instances these microplastics absorb directly into a microorganisms' biomolecules. However, before reaching this state any number of organisms could potentially interact with these plastics. During their expedition in 2016-17, Charles Moore and Algalita found that more than 35% of south Pacific Lanternfish had consumed plastic particles. When ingested by the fish the chemical compounds found in these plastics cannot be digested. This can effect Humans as the Lanternfish is a food source for both salmon and tuna. In their PNAS journal, Dr Van Sebille and his colleagues report data showing that in 1960 less than 5% of seabirds were found to have consumed waste material, while as of August 2015 that figure climbed to about 90%. It is predicted that by 2050, 99%of seabirds will have consumed such materials. Scientists studying the stomach contents of Laysan Albatross chicks report a 40% mortality rate before fledgling. When the stomach contents were analyzed following necropsies, they were found to contain plastic waste. Not only do plastic pellets used in manufacturing worldwide absorb toxic chemicals such as DDT and PCBs from the water, but can even leach chemicals such as biphenyl. It is estimated that up to 267 marine species are affected by plastic pollution. Granulation
In plastic recycling, granulation is the process of shredding plastic objects to be recycled into flakes or pellets, suitable for later reuse in plastics extrusion. In the first stage, plastic objects to be recycled are fed to an electric motor-powered cutting chamber, which continually cuts the material in scissor-like fashion. The material is ground into all the smaller flakes until they became fine enough to fall through a mesh screen. In wet-granulation lines, water is continually sprayed in the cutting chamber to remove the debris and impurities, and acts as a lubricant of the steel blades; in dry-granulation lines, water is not present, but such technology generally produces output of lower quality than the wet technology. While the process is relatively simple, it must be carefully parametrized, as the high temperatures resulting from friction can damage the material and affect its plasticity. Regular maintenance and sharpening of the scissor blades are essential, as well as close monitoring of the process due to potential clogging and jamming. Biodegradable additives
Interpretation of this process is as follows - In most cases, plastic is made up of hydrophobic polymers. Chains must be broken down into constituent parts for the energy potential to be used by microorganisms. These constituent parts, or monomers, are readily available to other bacteria. The process of breaking these chains and dissolving the smaller molecules into solution is called hydrolysis. Therefore, hydrolysis of these high-molecular-weight polymeric components is the necessary first step in anaerobic biodegradation. Through hydrolysis, the complex organic molecules are broken down into simple sugars, amino acids, and fatty acids. Plastic shopping bag
Some modern bags are made of vegetable-based bioplastics, which can decay organically and prevent a build-up of toxic plastic bags in landfills and the natural environment. Bags can also be made from degradable polyethylene film or from polylactic acid (PLA), a biodegradable polymer derived from lactic acid. However, most degradable bags do not readily decompose in a sealed landfill, and represent a possible contaminant to plastic recycling operations. In general, biodegradable plastic bags need to be kept separate from conventional plastic recycling systems. Biodegradable plastic
"This guide covered suggested criteria, procedures, and a general approach to establish the compostability of environmentally degradable plastics."[9] OXO-biodegradation
It is important to distinguish between "oxo-degradable" plastics, which fragment but do not biodegrade, except over a very long time, and "oxo-biodegradable" plastics which degrade and then biodegrade. Biodegradation
Plastic pollution from illegal dumping poses health risks to wildlife. Animals often mistake plastics for food, resulting in intestinal entanglement. Slow-degrading chemicals, like polychlorinated biphenyls (PCBs), nonylphenol (NP), and pesticides also found in plastics, can release into environments and subsequently also be ingested by wildlife. Film stock
All plastic is subject to deterioration through physical or chemical means, and thus, motion picture film is subject to the same deterioration. Films deteriorate over time, which can damage individual frames or even lead to the entire film being destroyed. Cellulose nitrate, cellulose diacetate and triacetate are known to be unstable mediums: improperly preserved film can deteriorate in a period of time much faster than many photographs or other visual presentations. Cellulose nitrate, because of its unstable chemistry, eventually breaks down, releasing nitric acid, further catalyzing the decomposition. In the final stages of celluloid decomposition, the film turns into a rust-like powder. Likewise, tri-acetate stock is also vulnerable to deterioration. Because of the small gauge of the film, owners of home-made films often find that their film can become shrunken and brittle to the point where the film is unwatchable in the space of a few years. In general, decaying acetate film breaks down into acetic acid, and similar to celluloid decomposition, leads to an auto-catylictic breakdown of the base that cannot be reversed. The result of the acetic acid released is a strong odor of vinegar, which is why the decay process in the archival community is known as "vinegar syndrome". Modern polyester-based stocks are far more stable by comparison and are rated to last hundreds of years if stored properly. Biodegradable plastic
While aromatic polyesters are almost totally resistant to microbial attack, most aliphatic polyesters are biodegradable due to their potentially hydrolysable ester bonds: Naturally Produced: Polyhydroxyalkanoates (PHAs) like the poly-3-hydroxybutyrate (PHB), polyhydroxyvalerate (PHV) and polyhydroxyhexanoate (PHH); Renewable Resource: Polylactic acid (PLA); Synthetic: Polybutylene succinate (PBS), polycaprolactone (PCL)... Polyanhydrides Polyvinyl alcohol Most of the starch derivatives Cellulose esters like cellulose acetate and nitrocellulose and their derivatives (celluloid). Polyethylene terephthalate Enhanced biodegradable plastic with additives.[3] Plastic
The common noun plastic should not be confused with the technical adjective "plastic". The adjective is applicable to any material which undergoes a plastic deformation, or permanent change of shape, when strained beyond a certain point.
For example, aluminum which is stamped or forged exhibits plasticity in this sense, but is not plastic in the common sense. By contrast, some plastics will, in their finished forms, break before deforming and therefore are not "plastic" in the technical sense. OXO-biodegradation
Oxo-biodegradable plastic, made from polymers such as polyethylene (PE), polypropylene (PP), and polystyrene (PS), contain a pro-degradant catalyst (often salts of manganese or iron), and are tested according to ASTM D6954 or BS8472 or AFNOR Accord T51-808 to degrade and then biodegrade in the open environment . The prodegradant catalyze the abiotic degradation process so that Oxo-biodegradable plastic will degrade in the presence of oxygen much more quickly than ordinary plastic  Hong Kong plastic disaster
Polypropylene has been widely used in daily life. Since it is resistant to heat, acid, alkali, chemical substance and collision and hard to biodegrade, it is often made into food containers to extend the expiration date of food, including microwavable food boxes, disposable tableware and goods packages. Whereas according to experience of the Great Pacific Garbage Patch, if the plastics are exposed to solar ultraviolet radiation for a long time, they will gradually be broken down into tiny molecules while still keeping the form of a polymer during the process of photo-degradation and continue floating on the sea. As the plastics are broken down, chemical substances that may be used to make plastics, such as Bisphenol A, will be released to the ocean. Meanwhile, thinner plastics will absorb all the chemical substances on the ocean surface, including carcinogens human beings discharge into the sea, forming a layer of "toxic soup" on the ocean surface. Photo-degraded plastics can be easily absorbed by the digestive system of fish and seabirds. Many toxic chemical substances, therefore, enter the food chain, causing unpredictable disaster to the ecosystem. Larger-volume plastic products may also choke the digestive system of saltwater fish and seabirds, which will then die of malnutrition. Biodegradable plastic
Compostable plastics combine the utility of plastics (lightweight, resistance, relative low cost) with the ability to completely and fully compost in an industrial compost facility. Rather than worrying about recycling a relatively small quantity of commingled plastics, proponents argue that certified biodegradable plastics can be readily commingled with other organic wastes, thereby enabling composting of a much larger portion of nonrecoverable solid waste. Commercial composting for all mixed organics then becomes commercially viable and economically sustainable. More municipalities can divert significant quantities of waste from overburdened landfills since the entire waste stream is now biodegradable and therefore easier to process. This move away from the use of landfills may help alleviate the issue of plastic pollution. Bioplastic
Biodegradation of any plastic is a process that happens at solid/liquid interface whereby the enzymes in the liquid phase depolymerize the solid phase Both bioplastics and conventional plastics containing additives are able to biodegrade. Bioplastics are able to biodegrade in different environments hence they are more acceptable than conventional plastics. Biodegradability of bioplastics occurs under various environmental conditions including soil, aquatic environments and compost. Both the structure and composition of biopolymer or bio-composite have an effect on the biodegradation process, hence changing the composition and structure might increase biodegradability. Soil and compost as environment conditions are more efficient in biodegradation due to their high microbial diversity. Composting not only biodegrades bioplastics efficiently but it also significantly reduces the emission of greenhouse gases. Biodegradability of bioplastics in compost environments can be upgraded by adding more soluble sugar and increasing temperature. Soil environments on the other hand have high diversity of microorganisms making it easier for biodegradation of bioplastics to occur. However, bioplastics in soil environments need higher temperatures and a longer time to biodegrade. Some bioplastics biodegrade more efficiently in water bodies and marine systems; however, this causes danger to marine ecosystems and freshwater. Hence it is accurate to conclude that biodegradation of bioplastics in water bodies which leads to the death of aquatic organisms and unhealthy water can be noted as one of the negative environmental impacts of bioplastics. Biodegradable plastic
Many people confuse "biodegradable" with "compostable". "Biodegradable" broadly means that an object can be biologically broken down, while "compostable" typically specifies that such a process will result in compost, or humus.[6] Many plastic manufacturers throughout Canada and the US have released products indicated as being compostable. The waste management infrastructure currently recycles regular plastic waste, incinerates it, or places it in a landfill. Mixing biodegradable plastics into the regular waste infrastructure poses some dangers to the environment.[7] However this claim is debatable, if the manufacturer was minimally conforming to the now-withdrawn American Society for Testing and Materials (ASTM standard definition of the word, as it applies to plastics: Biodegradable plastic
Under proper conditions, some biodegradable plastics can degrade to the point where microorganisms can completely metabolise them to carbon dioxide (and water). For example, starch-based bioplastics produced from sustainable farming methods could be almost carbon neutral. Plastic explosive
The British used a plastic explosive during World War II as a demolition charge. The specific explosive, Composition C, was 88.3% RDX and 11.7% non-oily, non-explosive plasticizer. The material was plastic between 0 and 40 degrees C, but was brittle at colder temperatures and gummy at higher temperatures. Composition C was superseded by Composition C2, which used a mixture of 80% RDX and 20% plasticizer. Composition C2 had a wider temperature range at which it remained plastic, from −30 to 52 degrees C. Composition C2 was replaced by Composition C3, which was a mixture of 77% RDX and 23% explosive plasticizer. C3 was effective but proved to be too brittle in cold weather and was replaced with C4. There are three classes of C4, with varying amounts of RDX and polyisobutylene. Plastic recycling
A process has also been developed in which many kinds of plastic can be used as a carbon source in the recycling of scrap steel. There is also a possibility of mixed recycling of different plastics, which does not require their separation. It is called compatibilization and requires use of special chemical bridging agents compatibilizers. It can help to keep the quality of recycled material and to skip often expensive and inefficient preliminary scanning of waste plastics streams and their separation/purification. Zero waste
The tension between zero waste viewed as post-discard total recycling of materials only, and zero waste as the reuse of all high-level function remains a serious one today. It is probably the defining difference between established recyclers and emerging zero-wasters. A signature example is a difference between smashing a glass bottle (recovering cheap glass) and refilling the bottle (recovering the entire function of the container).
The tension between the literal application of natural processes and the creation of industry-specific more efficient reuse modalities is another tension. Many observers look to nature as an ultimate model for production and innovative materials. Others point out that industrial products are inherently non-natural (such as chemicals and plastics that are mono-molecular) and benefit greatly from industrial methods of reuse, while natural methods requiring degradation and reconstitution are wasteful in that context.
Biodegradable plastic is the most prominent example. One side argues that biodegradation of plastic is wasteful because plastic is expensive and environmentally damaging to make. Whether made of starch or petroleum, the manufacturing process expends all the same materials and energy costs. Factories are built, raw materials are procured, investments are made, machinery is built and used, humans labor and make use of all normal human inputs for education, housing, food etc. Even if the plastic is biodegraded after a single use, all of those costs are lost so it is much more important to design plastic parts for multiple reuse or perpetual lives. The other side argues that keeping plastic out of a dump or the sea is the sole benefit of interest.
Companies moving towards "zero landfill" plants include Subaru, Xerox and Anheuser-Busch. Deformation (engineering)
This type of deformation is irreversible. However, an object in the plastic deformation range will first have undergone elastic deformation, which is reversible, so the object will return part way to its original shape. Soft thermoplastics have a rather large plastic deformation range as do ductile metals such as copper, silver, and gold. Steel does, too, but not cast iron. Hard thermosetting plastics, rubber, crystals, and ceramics have minimal plastic deformation ranges. An example of a material with a large plastic deformation range is wet chewing gum, which can be stretched dozens of times its original length. Marine pollution
The amount of awareness on marine pollution is vital to the support of keeping the prevention of trash from entering waterways and ending up in our oceans. The EPA reports that in 2014 Americans generated about 258 million tons of waste, and only a third was recycled or composted. In 2015, there was over 8 million tons of plastic that made it into the ocean. Through more sustainable packing this could lead to; eliminating toxic constituents, using fewer materials, making more readily available recyclable plastic. However, awareness can only take these initiatives so far. The most abundant plastic is PET (Polyethylene terephthalate) and is the most resistant to biodegradables. Researchers have been making great strides in combating this problem. In one way has been by adding a special polymer called a tetrablock copolymer. The tetrablock copolymer acts as a laminate between the PE and iPP which enables for an easier breakdown but still be tough. Through more awareness, individuals will become more cognizant of their carbon footprints. Also, from research and technology, more strides can be made to aid in the plastic pollution problem. Plastic
Thermoplastics can be remelted and reused, and thermoset plastics can be ground up and used as filler, although the purity of the material tends to degrade with each reuse cycle. There are methods by which plastics can be broken down to a feedstock state. Plastic recycling
Plastic recycling is the process of recovering scrap or waste plastic and reprocessing the material into useful products. Since the vast majority of plastic is non-biodegradable, recycling is a part of global efforts to reduce plastic in the waste stream, especially the approximately 8 million tons of waste plastic that enters the Earth's ocean every year. Phase-out of lightweight plastic bags
Even when disposed of properly, they take many years to decompose and break down, generating large amounts of garbage over long periods of time. Improperly discarded bags have polluted waterways, clogged sewers and been found in oceans, affecting the habitat of marine creatures. Environmental stress fracture
Plastics and plastic-based composites may suffer swelling, debonding and loss of strength when exposed to organic fluids and other corrosive environments, such as acids and alkalies. Under the influence of stress and environment, many structural materials, particularly the high-specific strength ones become brittle and lose their resistance to fracture. While their fracture toughness remains unaltered, their threshold stress intensity factor for crack propagation may be considerably lowered. Consequently, they become prone to premature fracture because of sub-critical crack growth. This article aims to give a brief overview of the various degradation processes mentioned above. South Pacific garbage patch
One study shows estimates of 5.25 trillion individual pieces of microplastcs, weighing nearly 267,000 tons are currently floating in our oceans. It has been estimated that since being invented, 8.3 billion tons of plastics has been produced, with 80% (6.64 billion tons) being dumped in landfills, on land, and in the oceans. Plastic particles don't biodegrade or break down and instead just fragment into smaller pieces. If current trends in the amount of plastics flowing into our oceans continues, combined with overfishing, will result in plastics outweighing fish in the oceans by 2050. Polymer degradation
Biodegradable plastics can be biologically degraded by microorganisms to give lower molecular weight molecules. To degrade properly biodegradable polymers need to be treated like compost and not just left in a landfill site where degradation is very difficult due to the lack of oxygen and moisture. Plastic pollution
There are varying rates of recycling per type of plastic, and in 2011, the overall plastic recycling rate was approximately 8% in the United States. Approximately 2.7 million tons of plastics were recycled in the U.S. in 2011. Some plastics are recycled more than others; in 2011 "29 percent of HDPE bottles and 29 percent of PET bottles and jars were recycled." Recrystallization (metallurgy)
During plastic deformation the work performed is the integral of the stress and strain in the plastic deformation regime. Although the majority of this work is converted to heat, some fraction (~1–5%) is retained in the material as defects — particularly dislocations. The rearrangement or elimination of these dislocations will reduce the internal energy of the system and so there is a thermodynamic driving force for such processes. At moderate to high temperatures, particularly in materials with a high stacking fault energy such as aluminium and nickel, recovery occurs readily and free dislocations will readily rearrange themselves into subgrains surrounded by low-angle grain boundaries.
The driving force is the difference in energy between the deformed and recrystallized state Δ"E" which can be determined by the dislocation density or the subgrain size and boundary energy (Doherty, 2005): Detritus
In biology, detritus () is dead particulate organic material (as opposed to dissolved organic material). It typically includes the bodies or fragments of dead organisms as well as fecal material. Detritus is typically colonized by communities of microorganisms which act to decompose (or remineralize) the material. In terrestrial ecosystems, it is encountered as leaf litter and other organic matter intermixed with soil, which is denominated "soil organic matter". Detritus of aquatic ecosystems is organic material suspended in water and piling up on seabed floors, which is referred to as marine snow.
Dead plants or animals, material derived from animal tissues (such as skin cast off during moulting etc) gradually lose their form, due to both physical processes and the action of decomposers, including grazers, bacteria and fungi. Decomposition, the process through which organic matter is decomposed, takes place in many stages. Materials like proteins, lipids and sugars with low molecular weight are rapidly consumed and absorbed by microorganisms and organisms that feed on dead matter. Other compounds, such as complex carbohydrates are broken down more slowly. The various microorganisms involved in the decomposition break down the organic materials in order to gain the resources they require for their own survival and proliferation. Accordingly, at the same time that the materials of plants and animals are being broken down, the materials (biomass) making up the bodies of the microorganisms are built up by a process of assimilation. When microorganisms die, fine organic particles are produced, and if these are eaten by small animals which feed on microorganisms, they will collect inside the intestine, and change shape into large pellets of dung. As a result of this process, most of the materials from dead organisms disappears from view and is not obviously present in any recognisable form, but is in fact present in the form of a combination of fine organic particles and the organisms using them as nutrients. This combination is detritus. Flow plasticity theory
The concept of multiplicative decomposition of the deformation gradient into elastic and plastic parts was first proposed independently by B. A. Bilby, E. Kröner, in the context of crystal plasticity and extended to continuum plasticity by Erasmus Lee. The decomposition assumes that the total deformation gradient (F) can be decomposed as:
where F is the elastic (recoverable) part and F is the plastic (unrecoverable) part of the deformation. The spatial velocity gradient is given by 
where a superposed dot indicates a time derivative. We can write the above as
The quantity
is called a plastic velocity gradient and is defined in an intermediate (incompatible) stress-free configuration. The symmetric part (D) of L is called the plastic rate of deformation while the skew-symmetric part (W) is called the plastic spin:
Typically, the plastic spin is ignored in most descriptions of finite plasticity. Recycling
Plastic recycling is the process of recovering scrap or waste plastic and reprocessing the material into useful products, sometimes completely different in form from their original state. For instance, this could mean melting down soft drink bottles and then casting them as plastic chairs and tables. Geodynamics
Ductile or plastic deformation happens when the temperature of a system is high enough so that a significant fraction of the material microstates (figure 1) are unbound, which means that a large fraction of the chemical bonds are in the process of being broken and reformed. During ductile deformation, this process of atomic rearrangement redistributes stress and strain towards equilibrium faster than they can accumulate. Examples include bending of the lithosphere under volcanic islands or sedimentary basins, and bending at oceanic trenches. Ductile deformation happens when transport processes such as diffusion and advection that rely on chemical bonds to be broken and reformed redistribute strain about as fast as it accumulates. Environmental impact of pharmaceuticals and personal care products
The coast of Guangdong is a place polluted by another representative contaminant, plastic debris. After an extended period of observation, scientists found that the beach was a place that would help the fragmentation of plastic debrisinto highly fragmented plastic particles that can attach to small organisms. Through the process of washback, the plastic debris may be transported into the water, and make an adverse impact on a wide range of marine life at different trophic levels. It is noticeable that polystyrene (PS) foams and fragments, and microplastics account for a great percentage of plastic debris on the beach. Most of the polystyrenes degrade within a year on average, and could not be observed in deep beach sediment. Thus, coastal beaches store highly fragmented and degraded micro-plastics. However, they may be active and return to the water. Wild fisheries
Marine debris is human-created waste that ends up floating in the sea. Oceanic debris tends to accumulate at the centre of gyres and coastlines, frequently washing aground where it is known as beach litter. Eighty percent of all known marine debris is plastic - a component that has been rapidly accumulating since the end of World War II. Plastics accumulate because they don't biodegrade as many other substances do; while they will photodegrade on exposure to the sun, they do so only under dry conditions, as water inhibits this process. Bioplastic
Bioplastics are plastics derived from renewable biomass sources, such as vegetable fats and oils, corn starch, straw, woodchips, food waste, etc. Bioplastic can be made from agricultural by-products and also from used plastic bottles and other containers using microorganisms. Common plastics, such as fossil-fuel plastics (also called petrobased polymers) are derived from petroleum or natural gas. Not all bioplastics are biodegradable nor biodegrade more readily than commodity fossil-fuel derived plastics. Bioplastics are usually derived from sugar derivatives, including starch, cellulose, and lactic acid. As of 2014, bioplastics represented approximately 0.2% of the global polymer market (300 million tons). Plastic recycling
Plastic #2, high-density polyethylene (HDPE) is a commonly recycled plastic. HDPE's highly crystalline structure makes it a strong, high density, moderately stiff plastic. HDPE Thermoplastic materials become liquid at their melting point - around 130 °C. A major benefit of thermoplastics is that they can be heated to melting point, cooled, and reheated again without significant degradation. Instead of burning, thermoplastics like PE (Polyethylene) liquefy, allowing them to be easily extruded or [injection molded] and turned into brand new [HDPE pipe]. Often it is typically downcycled into plastic lumber, tables, roadside curbs, benches, truck cargo liners, trash receptacles, stationery (e.g. rulers) and other durable plastic products and is usually in demand.  Plastic shopping bag
Biodegradable plastics are plastics that are decomposed by the action of living organisms, usually bacteria. Two basic classes of biodegradable plastics exist: Bioplastics, whose components are derived from renewable raw materials, and plastics made from petrochemicals containing biodegradable additives which enhance biodegradation. Disposable food packaging
In recent years manufacturers have been working on developing more sustainable alternatives to traditional plastic products. Amongst them are plates and cutlery made from bamboo and wood (mostly birch). Throughout the entire life cycle of wood products, there are far fewer environmental repercussions than with traditional plastics or so called "bioplastics" like PLA. The production process is free of chemicals and the products decompose usually in the matter of only a few months. Currently wood and bamboo products are more costly than traditional plastics and not as widely available, which makes it challenging for some restaurants to switch. Biodegradable plastic
In terms of ASTM industrial standard definitions, the U.S.Federal Trade Commission and the U.S. EPA set standards for biodegradability. ASTM International defines methods to test for biodegradable plastic, both anaerobically and aerobically, as well as in marine environments. The specific subcommittee responsibility for overseeing these standards falls on the Committee D20.96 on Environmentally Degradable Plastics and Bio based Products.[30] The current ASTM standards are defined as standard specifications and standard test methods. Standard specifications create a pass or fail scenario whereas standard test methods identify the specific testing parameters for facilitating specific time frames and toxicity of biodegradable tests on plastics. Great Pacific garbage patch
A 2017 study concluded that of the 9.1 billion tons of plastic produced since 1950, close to 7 billion tons are no longer in use.[38] The authors estimate that 9% was recycled, 12% was incinerated, and the remaining 5.5 billion tons remains in the oceans and land.[38] Plastic pollution
Efforts to reduce the use of plastics and to promote plastic recycling have occurred. Some supermarkets charge their customers for plastic bags, and in some places more efficient reusable or biodegradable materials are being used in place of plastics. Some communities and businesses have put a ban on some commonly used plastic items, such as bottled water and plastic bags. In January 2019 a "Global Alliance to End Plastic Waste" has been created. The alliance wants to clean the environment from existing waste and increase recycling, but it does not mention reduction in plastic production as one of its targets. Plastic pollution
As of 2018, about 380 million tons of plastic is produced worldwide each year. From the 1950s up to 2018, an estimated 6.3 billion tons of plastic has been produced worldwide, of which an estimated 9% has been recycled and another 12% has been incinerated. In the UK alone, more than 5 million tonnes of plastic are consumed each year, of which only an estimated one-quarter is recycled, with the remainder going to landfills. This large amount of plastic waste inevitably enters the environment, with studies suggesting that the bodies of 90% of seabirds contain plastic debris. In some areas there have been significant efforts to reduce the prominence of plastic pollution, through reducing plastic consumption and promoting plastic recycling. OXO-biodegradation
Oxo-degradable plastic, including plastic carrier bags, may degrade quicker in the open environment than conventional plastic. However, according to a report from the European Commission, there is no evidence that oxo-degradable plastic will subsequently fully biodegrade in a reasonable time in the open environment, on landfills or in the marine environment . According to the report: "Sufficiently quick biodegradation is in particular not demonstrated for landfills and the marine environment. A wide range of scientists, international and governmental institutions, testing laboratories, trade associations of plastics manufacturers, recyclers and other experts have therefore come to the conclusion that oxo-degradable plastics are not a solution for the environment and that oxo-degradable plastic is not suited for long-term use, recycling or composting. There is a considerable risk that fragmented plastics will not fully biodegrade and a subsequent risk of an accelerated and accumulating amount of microplastics in the environment, especially the marine environment. The issue of microplastics is long acknowledged as a global problem in need of urgent action, not just in terms of clean-up of littering, but also of plastic pollution prevention." Plastic pollution
Landfill areas contain many different types of plastics. In these landfills, there are many microorganisms which speed up the biodegradation of plastics. The microorganisms include bacteria such as "Pseudomonas", nylon-eating bacteria, and Flavobacteria. These bacteria break down nylon through the activity of the nylonase enzyme. Breakdown of biodegradable plastics releases methane, a very powerful greenhouse gas that contributes significantly to global warming. Polyvinyl chloride
Degradation during service life, or after careless disposal, is a chemical change that drastically reduces the average molecular weight of the polyvinyl chloride polymer. Since the mechanical integrity of a plastic depends on its high average molecular weight, wear and tear inevitably weakens the material. Weathering degradation of plastics results in their surface embrittlement and microcracking, yielding microparticles that continue on in the environment. Also known as microplastics, these particles act like sponges and soak up persistent organic pollutants (POPs) around them. Thus laden with high levels of POPs, the microparticles are often ingested by organisms in the biosphere. Biodegradable polythene film
These films are made by incorporating an additive within normal polymers to provide an oxidative and then a biological mechanism to degrade them. This typically takes 6 months to 1 year in the environment with adequate exposure to oxygen Degradation is a two-stage process; first the plastic is converted by reaction with oxygen (light, heat and/or stress accelerates the process but is not essential) to hydrophilic low molecular-weight materials and then these smaller oxidized molecules are biodegraded, i.e. converted into carbon dioxide, water and biomass by naturally occurring microorganisms. Commercial competitors and their trade associations allege that the process of biodegradation stops at a certain point, leaving fragments, but they have never established why or at what point. In fact Oxo-biodegradation of polymer material has been studied in depth at the Technical Research Institute of Sweden and the Swedish University of Agricultural Sciences. A peer-reviewed report of the work was published in Vol 96 of the journal of Polymer Degradation & Stability (2011) at page 919-928. It shows 91% biodegradation in a soil environment within 24 months, when tested in accordance with ISO 17556.
This is similar to the breakdown of woody plant material where lignin is broken down and forms a humus component improving the soil quality. 
There is however a lot of controversy about these types of bags. The complete biodegradation is disputed and claimed not to take place. Many countries are now also thinking to ban this type of bags altogether Plastic
Some polymers may also decompose into the monomers or other toxic substances when heated. In 2011, it was reported that "almost all plastic products" sampled released chemicals with estrogenic activity, although the researchers identified plastics which did not leach chemicals with estrogenic activity. Conservation and restoration of plastic objects
The cause of deterioration regarding plastics can be linked to age, chemical composition, storage, and improper handling of the objects. Conservators are in place to slow down the processes of deterioration by considering the 4 leading caused of deterioration:Understanding the different types of plastic chemical degradation as this helps determine what not to expose plastics to As the polymers that are composed of the plastics can deteriorate easily by changes in temperature, water or light it is important to understand how these affect the polymers. Listed below are the chemical reactions that occur with the deterioration of the polymer's structure.Additional effects of deterioration Glitter
Trisia Farrelly, an environmental anthropologist at Massey University, has called for a ban on glitter made of polyethylene terephthalate (PETE) and aluminium, as it is a microplastic that can break down to hormonal disruptors in the environment. Furthermore, plastic glitter takes about one thousand years to biodegrade, according to Victoria Miller, a materials and engineering scientist at North Carolina State University. When dozens of British music festivals pledged to ban single-use plastics by 2021, the proposed ban included plastic glitter. Plastic pollution
Plastics themselves contribute to approximately 10% of discarded waste. Many kinds of plastics exist depending on their precursors and the method for their polymerization. Depending on their chemical composition, plastics and resins have varying properties related to contaminant absorption and adsorption. Polymer degradation takes much longer as a result of saline environments and the cooling effect of the sea. These factors contribute to the persistence of plastic debris in certain environments. Recent studies have shown that plastics in the ocean decompose faster than was once thought, due to exposure to sun, rain, and other environmental conditions, resulting in the release of toxic chemicals such as bisphenol 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 nappy will take 450 years, and fishing line will take 600 years to degrade. Phase-out of lightweight plastic bags
Recycling of plastic bags can be another method of phase-out. However, a big issue with recycling is that only 5% of plastic bags make it to recycling facilities to begin with. Even when bags are brought to these recycling bins and facilities, they often fly out of these bins or recycling trucks and end up as litter on the streets. If there are any facilities of avoiding the plastics from flying out this would be a better method Another issue with recycling is that different bags are made from different yet aesthetically similar types of plastics. Bags can be either made of bioplastics or biodegradable plastics, and if accidentally combined in a compost, the bioplastics could contaminate the biodegradable composting. These bags can also jam recycling equipment when mixed with other types of plastic, which can be costly to repair. For example, costs of repairs rounded out to be about $1 million per year in San Jose, California.  Microplastics
Biodegradation is another possible solution to large amounts of microplastic waste. In this process, microorganisms consume and decompose synthetic polymers with using degrading enzymes. These plastics can then be used in the form of energy and as a source of carbon once broken down. The microbes could potentially be used to treat sewage wastewater, which would decrease the amount of microplastics that pass through into the surrounding environments. Biodegradable polymer
Each year hundreds of millions of tons of plastics are produced from petroleum. Most of these plastics will remain in landfills for years to come or litter the environment posing significant health risks to animals; however, the average person's lifestyle would be impractical without them (see Applications). One solution to this conundrum lies in biodegradable polymers. These polymers have the distinct advantage that over time they will break down. Dr. Geoffrey Coates headed research to create catalysts that can not only efficiently create these biodegradable polymers, but the polymers also incorporate the greenhouse gas and global warming contributor, CO, and, environmentally present ground-ozone producer, CO. These two gases can be found or produced in high concentrations from agricultural waste, coal, and industrial applications as byproducts. Not only do the catalysts utilize these normally wasted and environmentally unfriendly gases, but they also do it extremely efficiently with high turnover numbers and frequencies in addition to good selectivity. These catalysts have been actively used by Novomer Inc to make polycarbonates that can replace the current coating bisphenol A (BPA) found in many food and drink packaging. Novomer's analysis shows that if used in all cases, these biodegradable polymer coatings could not only sequester, but also avoid further production of CO in hundreds of millions of metric tons in just a single year. Biodegradable plastic
The use of biodegradable plastics, therefore, is seen as enabling the complete recovery of large quantities of municipal sold waste (via aerobic composting) that have heretofore been unrecoverable by other means except land filling or incineration. Plastic
The success and dominance of plastics starting in the early 20th century led to environmental concerns regarding its slow decomposition rate after being discarded as trash due to its composition of large molecules. Toward the end of the century, one approach to this problem was met with wide efforts toward recycling. Sustainable clothing
PET plastics are also known as Polyethylene terephthalate(PETE). PET's recycling code, the number within the three chasing arrows, is one. These plastics are usually beverage bottles (i.e. water, soda, and fruit juice bottles). According to the EPA, plastic accounts for 12% of the total amount of waste we produce. Recycling plastic reduces air, water, and ground pollution. Recycling is only the first step; investing and purchasing products manufactured from recycled materials is the next of many steps to living sustainably.
Clothing can be made from plastics. Seventy percent of plastic-derived fabrics come from polyester, and the type of polyester most used in fabrics is polyethylene terephthalate (PET). PET plastic clothing come from reused plastics, often recycled plastic bottles. The Coca-Cola Company, for example, created a "Drink2Wear" line of T-shirts made from recycled bottles. Generally, PET plastic clothing are made from recycled bottles as follows: plastic bottles are collected, compressed, baled, and shipped into processing facilities where they will be chopped into flakes, and melted into small white pellets. Then, the pellets are processed again, and spun into yarn-like fiber where it can be made into clothing.
One main benefit of making clothes from recycled bottles is that it keep the bottles and other plastics from occupying landfill space. Another benefit is that it takes 30% less energy to make clothes from recycled plastics than from virgin polyesters.
Burnished by a grant from the US. Environmental Protection Agency, associate professor,Young-A Lee and her team are growing vats of gel-like film composed of cellulose fiber, a byproduct of the same symbiotic colonies of bacteria and yeast (abbreviated SCOBY) found in another of the world's popular "live culture" foods: kombucha. Once harvested and dried, the resulting material has a look and feel much like leather. The fibres are 100 percent biodegradable, they also foster a cradle-to-cradle cycle of reuse and regeneration that leaves behind virtually zero waste. However, this material takes a long time to grow about three to four weeks under lab-controlled conditions. Hence mass production is an issue. In addition, tests revealed that moisture absorption from the air softens this material makes it less durable. Researchers also discovered that cold conditions make it brittle. Plastic
Microbial species capable of degrading plastics are known to science, and some are potentially useful for the disposal of certain classes of plastic waste. Holocene extinction
Some researchers suggest that by 2050 there could be more plastic than fish in the oceans by weight, with about of plastic being discharged into the oceans annually. Single-use plastics, such as plastic shopping bags, make up the bulk of this, and can often be ingested by marine life, such as with sea turtles. These plastics can degrade into microplastics, smaller particles that can affect a larger array of species. Microplastics make up the bulk of the Great Pacific Garbage Patch, and their smaller size is detrimental to cleanup efforts.