Tuesday, May 28, 2019

Polyhydroxybutyrate Essays -- Chemistry

Plastic industry has become of vital importance for the comfort and quality of our lives, due to numerous qualities as strength, lightness, low cost and durability. Their downside is the oppose impact over the environment, due to the accumulating of millions of tons per year. Therefore, the development of biodegradable plastics seems a key issue for further development. PHAs are hydroxyalkanoate polyesters that are used as susceptibility storage for bacterium. Polyhydroxybutyrate(PHB) is a biodegradable polymer, with similar properties to polypropylene, which gives it great potential as alternative source of plastics. PHB is linear polyester of D-3-hydroxybutyric acid, with high molecular weight, accumulated as a storage carbon in different microorganisms. The PHB-producing bacteria require an environment rich in sucrose, glucose or ethanol, all expensive raw materials. Efforts have been make in the past years to overcome those disadvantages, by producing PHB from plants. (Gehrke, 2009)The first attempts to establish fermentative production of PHA happened 40 years ago, using stains of Ralstonia eutropha and Alcaligenes latus.Biopol, a polymer developed by ICI (Imperial chemical Industries) was produced using a mutant stain Ralstonia eutropha using glucose as a carbon source. That was the start of the commercially available PHVBs, in the 1980s. After the change of proprietary to Monsanto, the bioplastics division was sold and the patent was bought by a Cambridge, (MA, U.S.A.) company called Metabolix (source press release 16 May 2001, Metabolix.com).The research continued, adding new naturally PHA- producing bacteria to the list, whilst other microorganisms were modified to do so. The carbon source usually used was gluc... ...ndia University of Pune.9.Mousavioun, P. (2011). Properties of Ligning and Polyhydroxybutyrate Blends. Queensland, Australia Queensland University of Technology.10.Nisha V. Ramadas, S. K. (2009). Polyhydroxybutyrate Production using Agro-industrial Residue as Substrate by Bacillus sphaericus NCIM 5149. Kerala matter Institute for Interdisciplinary Science and Technology.11.Peter H. Yu, H. C.-L.-H.-P. (1999). Conversion of industrial wastes by Alcaligenes Latus into Polyhydroxyalkanoates,.12.Product information . (fr an). Preluat de pe mirel plastics http//www.mirelplastics.com/discover/default.aspx?ID=178313.Udpuay, S. C. (2008). Production and Characterization of Polyhydroxybutyrate from Molasses and Corn plunk Liquor produced by Bacillus megaterium ATCC 6748 . Phitsanulok ,Thailand Dept. of Biology, Fac. of Science, Naresuan University, .

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