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Introduction to Biodegradable Polymers
Published in Arbind Prasad, Ashwani Kumar, Kishor Kumar, Biodegradable Composites for Packaging Applications, 2023
Arbind Prasad, Gourhari Chakraborty, Ashwani Kumar, Kishor Kumar
The worldwide bioplastics creation limits are hard to assess and are typically founded on estimate because of the persistently arising scope of bio-based and biodegradable polymers and rising interests on putting resources into bioplastics area. In this time of urbanization, the depletion of petrol-based resources is at a higher recurrence. They are the most broadly utilized assets finding applications in pretty much every day of life. However, these assets are at the edge of a steady loss, at a lot higher rate than anybody could might suspect, helping toward ecological dangers [6]. The design of biodegradable plastics makes them easily degradable by normal microorganisms, giving a final result that is less destructive to the environment. In this way, biodegradable plastics are seen to be eco-friendly because of their natural advantages, which are difficult to deny compared to customary plastics. These materials are extricated from bounteously accessible natural sources. Bio-based polymers are produced from three sources, which are as follows: From agriculture sources through chemical treatments, such as polysaccharides and lipids (starch, cellulose, and alginates).From microorganisms (by fermentation), such as polyhydroxyalkanoates (PHAs) and polyhydroxybutyrate (PHBs).Conventional synthesis, such as polylactides, PBS, PE, PTT, PPP, etc.
Biopolymer Layered Silicate Nanocomposites: Effect on Cloisite 10 A on Thermal, Mechanical and Optical Properties
Published in Mahmood Aliofkhazraei, Advances in Nanostructured Composites, 2019
Okan Akin, Hale Oguzlu, Onur Ozcalik, Funda Tihminlioglu
PHAs are produced by different kind of microorganisms as energy storage material and classified as biodegradable and biocompatible thermoplastic polymer. Polyhydroxybutyrate (PHB) and its copolymers polyhydroxyvalerate (PHBV) are the most commonly used PHAs, which are promising polymers in especially food packaging applications due to its properties being similar to conventional synthetic plastics, e.g., polypropylene as a substitute to synthetic ones and recently in biomedical areas. However, PHAs suffer from brittleness and poor processing temperature range that limits its application areas (Reddy et al. 2003). In order to overcome these, various approaches have been used in literature such as by blending with other biodegradable plastics (Nguyen et al. 2010, Zhang and Thomas 2011) and oil based polymers with the aim of improving its mechanical properties, unfortunately with only limited success up until now (Garcia-Quesada et al. 2012). Therefore, to overcome the problems, nanocomposite technology could be used for improving the PHA’s properties.
Agricultural biotechnology
Published in Firdos Alam Khan, Biotechnology Fundamentals, 2018
Polyhydroxyalkanoates (PHAs), such as polyhydroxybutyrate (PHB), are synthesized from acetyl-CoA used as precursor and are used for the synthesis of biodegradable plastics with thermoplastic properties. At present, PHAs are produced by bacterial fermentation, and the cost of biodegradable plastic is substantially higher than that of synthetic plastics. Attempts are being made to produce PHAs in transgenic plants to reduce the cost. Genes encoding the two enzymes, acetoacetyl-CoA reductase (PhbB) and PHB synthase (phbC), involved in the PHB synthesis from the precursor acetyl-CoA have been transferred from the bacterium Alcaligenes eutrophus and expressed in Arabidopsis thaliana. When the two enzymes were targeted into the plastids, PHB accumulated in leaves. PHB production by transgenic plants provides an example of a novel compound synthesized in plants. Transgenic trees like popular expressing phbB and phbC accumulate PHB in their leaves. The leaves are collected and used for PHB extraction.
Modeling the bioconversion of starch to P(HB-co-HV) optimized by experimental design using Bacillus megaterium BBST4 strain
Published in Environmental Technology, 2019
Mauricio A. Porras, Fernando D. Ramos, María S. Diaz, María A. Cubitto, Marcelo A. Villar
Polyhydroxyalkanoates (PHAs) are one of the main bio-based polymers considering current worldwide biopolymers production [1]. They are natural biodegradable polymers produced by bacteria in their cytoplasm as a carbon reserve [2] that would contribute to reduce the environmental impact generated by disposal of synthetic plastics [3]. Considering this characteristic and the high dependence that nowadays materials have from fossil fuels, PHAs became an attractive alternative to conventional petrochemical plastics due to their mechanical and thermal properties [4,5]. Furthermore, PHAs can be used in packaging, as well as pharmaceutical and medical applications due to their biocompatibility and slow hydrolytic degradation [6]. More common PHA, polyhydroxybutyrate (PHB) homopolymer, does not possess good material properties for the industry, because of its crystalline and brittle nature. On the other hand, PHA copolymers, such as poly(hydroxybutyrate-co-hydroxyvalerate) (P(HB-co-HV)), are more strong and flexible, and of greater industrial interest [7,8]. P(HB-co-HV) can be highlighted as an interesting candidate to be used in biomedical areas [9–11].
From trash to treasure: review on upcycling of fruit and vegetable wastes into starch based bioplastics
Published in Preparative Biochemistry & Biotechnology, 2023
Subhankar Das, Manjula Ishwara Kalyani
Conventional synthetic plastics which includes Polyethylene (PE), Polypropylene (PP), Polyvinyl chloride (PVC), Polystyrene or Styrofoam (PS), Polyethylene terephthalate (PET), Polyurethane (PU), Polyamide (PA), Polytrimethylene terephthalate (PTT) are used on a daily basis. These synthetic plastics due to the mismanagement of proper disposal as well as due to the durability of the polymers, takes longer period to get degraded causing detrimental effects toward the environment.[5,6,9–11] As a result of increased public awareness toward environmental sustainability, there is a pressing need to develop a polymer that is easily degradable for everyday use. As illustrated in Figure 1, Biodegradable polymers can be produced from a variety of renewable resources and can further be broadly classified into: conventional biotechnologically derived polymers, microbial derived polymers, biomass derived or agrobased, which can further be divided into polysaccharide based polymers, lignocellulose based polymers, animal and plant protein based polymers, Aliphatic polyester, Aliphatic-aromatic polyesters, Poly (vinyl alcohol) PVOH. The biodegradable plastics can be produced from a wide variety of biopolymers, which include Poly (lactic acid) (PLA), Poly (D-lactide) (PDLA), Poly (DL-lactide) (PDLLA), Polyhydroxyalkanoates (PHA), Polyhydroxybutyrate (PHB), PHB co-hydroxyvalerate (PHBV), wood, straw wheat starch, potato starch, corn starch, casein, whey, gelatin, zein, soya, gluten, etc. These polymers are generally considered the most eco-friendly alternative to conventional petrochemical based polymers because of the renewable raw materials used to synthesize them and also they are easily biodegradable in nature. Use of bioplastics has some advantages over conventional synthetic plastics, such as low carbon footprint, less toxic, energy efficient and eco-friendly.[15–18] Starch, which is a naturally occurring soluble carbohydrate that are stored as energy by plants. Starch is composed of branched and unbranched glucose sub-units that are bonded together by glyosidic bonds. The unbranched unit of starch is called amylose and is joined together by α-1,4-glycosidic linkages. Amylose is amorphous in nature. The branched units of the starch, which is called amylopectin, are interlinked using α-1,6-glycosidic linkage and also comprise an unbranched amylose chain linked by α-1,4-glycosidic. Amylopectin is mainly found in crystalline form in nature. Starch is abundantly found in a wide variety of plants, which include corn, potatoes, cassava, rice, etc. Starch based bioplastic seems to be a better alternative compare to fossil based plastics in terms of low-cost, renewablilty, and availability of the biomaterial source, making it an ideal raw material for the production of biodegradable polymers.[19,20]