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Biodegradable plastics are plastics that can be decomposed by the action of living organisms, usually microbes, into water, carbon dioxide, and biomass. Biodegradable plastics are commonly produced with renewable raw materials, micro-organisms, petrochemicals, or combinations of all three. While the words "bioplastic" and "biodegradable plastic" are similar, they are not synonymous. Not all bioplastics (plastics derived partly or entirely from biomass) are biodegradable, and some biodegradable plastics are fully petroleum based. As more companies are keen to be seen as having "Green" credentials, solutions such as using bioplastics are being investigated and implemented more. The definition of bioplastics is still up for debate. The phrase is frequently used to refer to a wide range of diverse goods that may be biobased, biodegradable, or both. This could imply that polymers made from oil can be branded as "bioplastics" even if they have no biological components at all. However, there are many skeptics who believe that bioplastics will not solve problems as others expect. History Polyhydroxyalkanoate (PHA) was first observed in bacteria in 1888 by Martinus Beijerinck. In 1926, French microbiologist Maurice Lemoigne chemically identified the polymer after extracting it from Bacillus megaterium. It was not until the early 1960s that the groundwork for scaled production was laid. Several patents for the production and isolation of PHB, the simplest PHA, were administered to W.R. Grace & Co. (USA), but as a result of low yields, tainted product and high extraction costs, the operation was dissolved. When OPEC halted oil exports to the US to boost global oil prices in 1973, more plastic and chemical companies began making significant investment in the biosynthesis of sustainable plastics. As a result, Imperial Chemical Industries (ICI UK) successfully produced PHB at a yield of 70% using the strain Alcaligenes latus. The specific PHA produced in this instance was a scl-PHA. Production efforts slowed dramatically due to the undesirable properties of the PHA produced and the diminishing threat of rising oil prices soon thereafter. In 1983, ICI received venture capital funding and founded Marlborough Biopolymers to manufacture the first broad-application biodegradable plastic, PHBV, named Biopol. Biopol is a copolymer composed of PHB and PHV, but was still too costly to produce to disrupt the market. In 1996, Monsanto discovered a method of producing one of the two polymers in plants and acquired Biopol from Zeneca, a spinout of ICI, as a result of the potential for cheaper production. As a result of the steep increase in oil prices in the early 2000s (to nearly $140/barrel US$ in 2008), the plastic-production industry finally sought to implement these alternatives to petroleum-based plastics. Since then, countless alternatives, produced chemically or by other bacteria, plants, seaweed and plant waste have sprung up as solutions. Geopolitical factors also impact their use. Application Biodegradable plastics are commonly used for disposable items, such as packaging, cutlery, and food service containers. In principle, biodegradable plastics could replace many applications for conventional plastics. However, this entails a number of challenges. Many biodegradable plastics are designed to degrade in industrial composting systems. However, this requires a well-managed waste system to ensure that this actually happens. If products made from these plastics are discarded into conventional waste streams such as landfill, or find their way into the open environment such as rivers and oceans, potential environmental benefits are not realised and evidence indicates that this can actually worsen, rather than reduce, the problem of plastic pollution. Plastic items labelled as 'biodegradable', but that only break down into smaller pieces like microplastics, or into smaller units that are not biodegradable, are not an improvement over conventional plastic. A 2009 study found that the use of biodegradable plastics was financially viable only in the context of specific regulations which limit the usage of conventional plastics. For example, biodegradable plastic bags have been compulsory in Italy since 2011 with the introduction of a specific law. Types Bio-based plastics Biologically synthesized plastics (also called bioplastics or biobased plastics) are plastics produced from natural origins, such as plants, animals, or micro-organisms. Polyhydroxyalkanoates (PHAs) Polyhydroxyalkanoates are a class of biodegradable plastic naturally produced by various micro-organisms (example: Cuprividus necator). Specific types of PHAs include poly-3-hydroxybutyrate (PHB), polyhydroxyvalerate (PHV) and polyhydroxyhexanoate (PHH). The biosynthesis of PHA is usually driven by depriving organisms of certain nutrients (e.g. lack of macro elements such as phosphorus, nitrogen, or oxygen) and supplying an excess of carbon sources. PHA granules are then recovered by rupturing the micro-organisms. PHA can be further classified into two types: scl-PHA from hydroxy fatty acids with short chain lengths including three to five carbon atoms are synthesized by numerous bacteria, including Cupriavidus necator and Alcaligenes latus (PHB). mcl-PHA from hydroxy fatty acids with medium chain lengths including six to 14 carbon atoms, can be made for example, by Pseudomonas putida. Polylactic acid (PLA) Polylactic acid is thermoplastic aliphatic polyester synthesized from renewable biomass, typically from fermented plant starch such as from corn, cassava, sugarcane or sugar beet pulp. In 2010, PLA had the second-highest consumption volume of any bioplastic of the world. PLA is compostable, but non-biodegradable according to American and European standards because it does not biodegrade outside of artificial composting conditions (see § Compostable plastics). Starch blends Starch blends are thermoplastic polymers produced by blending starch with plasticizers. Because starch polymers on their own are brittle at room temperature, plasticizers are added in a process called starch gelatinization to augment its crystallization. While all starches are biodegradable, not all plasticizers are. Thus, the biodegradability of the plasticizer determines the biodegradability of the starch blend. Biodegradable starch blends include starch/polylactic acid, starch/polycaprolactone, and starch/polybutylene-adipate-co-terephthalate. Others blends such as starch/polyolefin are not biodegradable. Cellulose-based plastics Cellulose bioplastics are mainly the cellulose esters, (including cellulose acetate and nitrocellulose) and their derivatives, including celluloid. Cellulose can become thermoplastic when extensively modified. An example of this is cellulose acetate, which is expensive and therefore rarely used for packaging. Lignin-based polymer composites Lignin-based polymer composites are bio-renewable natural aromatic polymer.... Discover the Susan Yuan popular books. Find the top 100 most popular Susan Yuan books.