CHEMISTRY ASSESSMENT

Topics: Polymer, Cellulose, Monomer Pages: 6 (2176 words) Published: April 12, 2015
CHEMISTRY ASSESSMENT
Use available evidence to gather and present data from secondary sources and analyse progress in the recent development and use of a named biopolymer. This analysis should name the specific enzyme(s) used or organism used to synthesise the material and an evaluation of the use or potential use of the polymer produced related to its properties Introduction

-Biopolymer are polymers that are produced totally or in large part by living organisms. Unlike petroleum based polymers they have the special properties of being renewable and biodegradable. An example of a biopolymer is PHB (polyhydroxybutyrate) -PHB is a natural polyester polymer produced by the bacteria/enzyme Alcaligenes Eutrophus as an energy storage material.

Production
- To produce the biopolymer PHB, genetically modified bacteria such as Alcaligenes Eutrophus is placed in an aqueous medium and supplied with a rich carbon based food source such as glucose, providing growth(bacteria getting bigger) and proliferation(bacteria dividing and multiply). -Once the population is large enough it is moved to a different environment where certain nutrients such as nitrogen is restricted from the nutrient supply so the organism stops reproduction and the bacteria produces PHB as a nutrient source to be metabolised later. -When the process is done the bacteria is lysed (cut open) and cleaned, PHB is extracted with a solvent which can be a number of different substances, this too is separated from the remaining mass. By placing the solvent into water, PHB will precipitate into a fine white powder with a purity of at least 98%, the solvent is also usually recycled in a closed system. -The powder collected in the extraction stage can be made into pellets or small chunks using machinery, to improve durability and strength, plasticisers can be added, these pellets can be used in moulds or made into larger pieces by compaction. Properties

-High tensile strength of 40mPa(with additives)
-Thermoplastic (softens when heated, flexible, easily reshaped and is recyclable) -Insoluble in water
-High MP
-Biodegradability
-Biocompatibility/Non-Toxicity
-Brittle however it can be genetically manipulated with additives in order to make it more durable. Uses
-Can be used in the fast food industry for things such as utensils, cups and plates because PHB is insoluble in water, non-toxic, high tensile strength and biodegradable -The biodegradability of PHB has great appeal for the potential replacement of widely used polymers derived from petrochemicals. Petrochemicals such as polypropylene and polyethylene are often used for packaging, although they are hazardous to the environment, as when they are discarded they do not decompose. -PHB could thus be a replacement – for disposable nappies and packaging in the form of bottles, plastic bags and cling film as PHB is flexible, biodegradable and non-toxic. -This would eliminate the need for recycling – without fear of pollution, for PHB can be completely decomposed by bacteria into only carbon dioxide and water. -The biocompatibility and biodegradability of PHB also open it to many other uses, which are currently not possible with other petrochemical products. -PHB is currently being utilised in the medical industry, where plates can be made from PHB to be left in place to heal fractured bones due to its strength and once the bones heal PHB is slowly broken down within the body without any adverse effects. -Sutures can also be made from PHB as it is non-toxic and biocompatible meaning that it won’t be rejected from the human body as it is insoluble in water meaning that it won’t dissolve in the body Advantages

-It is biodegradable so unlike polyethylene and other petroleum derived plastics it will help to reduce the levels of rubbish in landfills. -It is compatible with organisms (biocompatible) so therefore it is not rejected by our body’s immune system so it can be used safely -It is a renewable...
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