An example of a polymer is PH (polyhydroxybutyrate) -PH is a natural polyester polymer produced by the bacteria/enzyme Allegiances Torturous as an energy storage material. Production – To produce the polymer PH, genetically modified bacteria such as Allegiances Torturous 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 PH as a nutrient source to be metabolites later. -When the process is done the bacteria is lased (cut open) and cleaned, PH 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, PH 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 trench, plasticizer can be added, these pellets can be used in moulds or made into larger pieces by compaction.
Properties -High tensile strength of mamma(with additives) -Thermoplastic (softens when heated, flexible, easily reshaped and is recyclable) -Insoluble in water -High PM -Biodegradability -Absorbability/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 PH is insoluble in water, non-toxic, high tensile strength and degradable -The biodegradability of PH 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. -PH could thus be a replacement for disposable nappies and packaging in the form of bottles, plastic bags and cling film as PR is flexible, biodegradable and non-toxic. -This would eliminate the need for recycling – without fear of pollution, for PH can be impolitely decomposed by bacteria into only carbon dioxide and water. The absorbability and biodegradability of PH also open it to many other uses, which are currently not possible with other petrochemical products. -PH is currently being utilized in the medical industry, where plates can be made from PH to be left in place to heal fractured bones due to its strength and once the bones heal PH is slowly broken down within the body without any adverse effects. Sutures Can also be made from PH as it is non-toxic and objectionable 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 (objectionable) so therefore it is not rejected by our body’s immune system so it can be used safely -It is a renewable resource Disadvantages -The main disadvantage of PH is that it is extremely expensive to produce, costing approximately 4 times that of polyethylene. The demand for PH currently is not high enough for its production to be economically viable -The reduction of PH requires medical professionals which in summary WOUld increase the cost of production -Extremely brittle so therefore it cannot sustain high impacts while being used however currently this has been solved by adding plasticizer and other additives yet this increases the cost of production. -The recovery of the polymer can be difficult while giving only modest yields.
Evaluation and Current progress -Currently PH is considered not an efficient alternative to petroleum based polymers such as ethylene due to its cost as it is approximately 4 times for expensive than ethylene. However as technology advances it may one day become an efficient alternative as modifications such as additives are used to make the polymer more cost-effective as well as different production are being sought out. -For example, experiments are being done to find an alternative for nutrient sources.
They are starting to be derived from waste material such as molasses and other agricultural wastes. This will in turn reduce the cost of production greatly -Also recent genetic engineering results have proven that transferring the enzyme, Allegiances Torturous into E. Coli acetate will create an environment that will allow faster growth, higher yields and easier recovery meaning that one day PH can become a viable alternative to petroleum based polymers.
Discuss the need for alternative sources of the compounds presently obtained from the petrochemical industry -Many polymers and fuels are currently derived from petrochemicals such as crude oil which are convenient and economical – Petrochemicals are chemicals made from compounds of natural gas, coal and petroleum -Over the last century the use of petrochemicals has increased dramatically since it serves as a primary source f energy for transportation, while it is also used to produce materials such as plastic. However the world reserves of petrochemicals are dwindling due to: There nature of being a non-renewable and unsustainable resource Increasing rates of consumption and demand Rising costs due to its depletion Substantial environmental issues such as pollution from the combustion of these petrochemicals and the release Of greenhouse gases. -Currently, it is predicted that the Australia’s crude oil and petroleum reserves will last around another 10-20 years and since fossil fuels are not renewable they will non run out -Therefore we need an alternative source of petrochemicals that are renewable and sustainable and that source is biomass. Biomass: carbon based material produced by living organisms, mainly plants -Alternative sources such as biomass would be favorable to use as it would prevent problems such as: Facing the same problem of exhaustion that petroleum will be facing soon Causing the release of more carbon into the carbon pool in the form of carbon dioxide Explain what is meant by a condensation polymer -A polymer formed when monomers combine via a chemical process called indentation which involves the elimination of a small molecule (often water or methane) as by-product when pairs of monomer molecules join together.
Examples of condensation polymers include natural ones such as cellulose, starch, cotton and also synthetic (man made) ones such as polyester, nylon and PET Describe the reaction involved when a condensation polymer is formed -In a condensation reaction two monomers chemically combine by eliminating a small molecule as by-product (usually water or methane) – Two molecules join together and release another. The type of end product resulting from a indentation popularization is dependent on the number of functional end groups of the monomer which can react -Usually formed by the reaction of 2 functional groups egg.
C-NAH (amine), C-OH (alcohol), O=C-OH (carboxylic acid), O=C-NAH (Amide) n(HO-C6H1004-B) + (n – 1)H2O -In the formation of cellulose seen above, n p glucose monomers combine to form the cellulose chain and (n – 1) molecules of water where n is the number of monomers – When two ; glucose monomers react, a hydroxyl group from each combine to condense a water molecule, leaving an oxygen atom linking the two monomers. – This process repeats to form a long chain
Describe the structure of cellulose and identify it as an example of a condensation polymer found as a major component of biomass -Cellulose consists of a hexagonal carbon based rings with five carbons and a lone oxygen atom in each ;-glucose monomer. The bottom 4 carbons each have a hydrogen and hydroxyl group linked where it has free electrons and the lone carbon on top has a hydrogen and COACH group -Cellulose as said in the previous dot point is a natural condensation polymer that undergoes a condensation reaction with the removal of water – For bonding to occur, every second glucose molecule must be inverted.
This results in the COACH group to be inverted, resulting in a linear structure Of the polymer. Strong H bonding between OH groups makes cellulose strong hard and resistant to chemical attack and insoluble in water since the hydroxyl groups cannot interact with water and they therefore cannot break the hydrogen bonds. This is an example of why cellulose can be used in building material such as wood and insulation -Also the bulky COACH substitutes makes accounts for cellulose rigidness and high crystalline. The existence of both intra-chain (within chains) and inter-chain (between chains) hydrogen bonding makes cellulose a very strong and hard to separate monomer. -Since cellulose has hundreds and thousands of ;-glucose monomers in a chain it is hard, rigid and has a high melting point. -In summary there are many factors that make cellulose a very strong and rigid polymer. Cellulose is the most abundant polymer in nature since it is used in cell walls to provide strength -Normal dry plant matter (which forms a large proportion of the earth’s biomass) are made of about 50% cellulose, and plants on earth produce approximately 500 billion tones of the substance each year. Therefore it is the most abundant component of the biomass.
It is a renewable source that is formed during photosynthesis Identify that cellulose contains the basic carbon-chain structures needed to build petrochemicals and discuss its potential as a raw material -The basic carbon-chain structures that are used to make petrochemicals are short- chained alikeness such as ethylene, propane and butane and since glucose contains six carbons it has the potential to be used to convert into the alikeness aforementioned Cellulose to Ethylene -Cellulose is a major component of biomass where cellulose itself can be Rosen down and since it is from biomass It is renewable. This means that cellulose contains the basic carbon chain structures that can be used to build compounds that are presently obtained from petrochemicals -However before it can be used in petrochemicals it must be converted in to ethylene through these steps: 1 . Break the cellulose down into glucose using either Decomposition with Noah and cellulose or Acid Hydrolysis (with heating) The reason for using these methods is that there are many hydrogen bonds between chains making cellulose quite compact and hard to separate. 2. Fermentation of glucose into ethanol Yeast and bacteria ferment the glucose down into ethanol, releasing CA Egg.