The Life of a Polymer

Polymers are an essential part of modern life. They are everywhere and taken for granted as a part of our lives. The production of polymers and plastics is part of the industrial landscape of Teesside.

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Until recently we haven’t really considered the impact of our polymer obsession on the environment and the use of resources in the making and disposing of polymers. We are now encouraged to recycle plastics and are being charged for plastic bags from shops.

recycle_shape

Your task is to take an addition polymer of your choice and try to follow the process from synthesis to use to disposal. You should consider the chemistry involved showing the monomers and polymerisation process and highlight the energy and resources consumed in its production. You should link the chemistry with function and properties and also show how the use of renewable resources, renewable energy, recycling and energy recovery can contribute to a more sustainable and greener industry.

Remember our findings from Journal Club and use a variety of different sources, evaluate your sources of information and cite everything you use.

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9 thoughts on “The Life of a Polymer

  1. Polytetrafluoroethylene:

    Tetrafluoroethylene:

    https://goo.gl/k26Ixq

    Polytetrafluoroethylene:

    https://goo.gl/pyzOEm

    Uses of polytetrafluoroehtylene:

    ➢ Cable insulation
    ➢ Reactor and plant equipment linings as it is good if it is highly corrosive.
    ➢ As a permeable membrane for clothing and shoes which allows vapour to diffuse away from the skin but prevents liquid from soaking in.
    ➢ Non stick utensils like frying pans.

    Properties:

    It is only broken down by hot fluorine gas or certain molten metals and therefore is resistant to corrosion. As it is a natural lubricant, this makes it excellent for cooking utensils as it allows a high heat to be used while maintaining a stable structure which is non stick when frying.

    How it is made:

    PTFE is polymerised from the chemical compound TFE which is synthesied from fluorspar, hydrofluoric acid and chloroform. TFE is manufactured at between 590-900°C. TFE is a colourless gas, which is highly flammable, so is stored as a liquid.

    To be polymerised, a small amount of chemicals are used as initiators. Some initiators are ammonium persulfate or disuccinic acid peroxide. A reaction is filled with purified water and an initiator will be set off. Liquid TFE is then added to the chamber and as it meets the initiator it will begin to polymerise. The chamber is shaken and solid grains begin to form. The chamber is cooled by a water jacket which allows heat to be removed from the chamber. Once enough PTFE has been produced it will shut off. The PTFE is then fed into a mill which pulverises the material into fine powder. This is then made into larger granules by another process.

    PTFE is recycled:
    It is thermally recycled with fluoropolymers being converted into their monomers with 90% efficiency. Although it is useful in terms of maintaining reactants it has a high energy requirement so it still costs.

    https://goo.gl/MCtGq1

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  2. Polypropylene

    Formation

    n CH-CH=CH2 > [-CH-CH2-]
    |
    [ CH3
    Propylene Polypropylene

    Production

    Hydrocarbon slurry or suspension which is using a liquid inert hydrocarbon diluent in the reactor to facilitate transfer of propylene to the catalyst, the removal of heat from the system, the deactivation/removal of the catalyst as well as dissolving the atactic polymer. The range of grades that could be produced was very limited. (The technology has fallen into disuse).

    Gas-phase process

    A mixture of propene and hydrogen is passed over a bed containing the Ziegler-Natta catalyst at temperatures of 320-360 K and a pressure of 8-35 atm.

    The polymer is separated from the gaseous propene and hydrogen using cyclones and the unreacted gas is recycled.
    Both processes can be operated continuously and use ‘stereospecific’ Ziegler-Natta catalysts to effect the polymerization. The catalyst remains in the product and needs to be destroyed using water or alcohols, before the polymer is converted into pellets.
    Both bulk and gas phase processes have virtually eliminated gaseous and aqueous effluents by the use of high activity catalysts, resulting in low residues in the final polymer.

    Bulk Process

    Polymerization takes place in liquid propene, in the absence of a solvent at a temperature of 340-360 K and pressures of 30-40 atm (to keep the propene as a liquid). After polymerization, solid polymer particles are separated from liquid propene, which is then recycled.
    The use of liquid propene as a solvent for the polymer as it is formed means that there is no need to use hydrocarbons such as the C4-C8 alkanes which are used in the parallel manufacture of poly(ethene).

    Properties

    Tough and flexible as the additional methyl group improves mechanical properties and thermal resistance, while chemical resistance decreases.

    Uses:
    – Manufacturing piping systems
    – Chairs/ furniture
    – Clothing – diapers and sanitary products
    – Medical – hernia and pelvic
    – Repairing – resistant to most solvents and glues
    – EPP model aircraft- absorbs kinetic impacts well

    How to dispose of:
    – Polypropene is recyclable.

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  3. Polystyrene – poly (1-phenylethene-1,2-diyl)

    Polystyrene Production –
    Polystyrene is formed from the polymerisation of styrene monomers. The pi-bonds involved in the C=C double bond are broken to form new C-C bonds between styrene monomers. The mechanism from joining styrene monomers is free radical addition polymerisation. In initiation, a free radical is added to the styrene monomer. Chain propagation occurs when styrene radicals collide with styrene monomers. This forms a short chain monomer of two styrene molecule and is itself a radical. This stage continues until termination; when two radicals collide they join to form a product that is not a radical – this is termination. The resultant product will be a polymer of styrene however it is possible that not all of the monomers have joined this polymer.

    Structure and Properties –
    • It is an aromatic hydrocarbon due to the benzene function group.
    • Has strong hydrocarbon backbone with weak induced dipole-dipole forces meaning it can be softened and moulded after being heated.
    • It is brittle as it is a homopolymer (a polymer that contains a singly repeating monomer).

    Uses –
    • Food Containers
    • Packaging
    • Modelling
    • CD “jewel” cases

    Disposal –
    Polystyrene is non-biodegradable and it takes hundreds of years to decompose. This is due to it being resistant to photolysis – breaking down by photons. As litter, polystyrene can be dangerous to animals and when in the ocean it can be hazardous to marine life as it could lead to the transfer of toxic chemicals. Used polystyrene can be incinerated after use. Providing it is incinerated to temperatures of 1000C with sufficient oxygen, polystyrene produces very few harmful products. Yet if the incineration is incomplete (without sufficient oxygen), there will be leftover carbon soot and a mixture of harmful substances. Polystyrene is not part of a mainstream recycling program and hence in many countries the use of polystyrene is banned for food containers.

    Document with images: tomclennett.wordpress.com

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  4. Polyisobutylene

    This is one of the more unique polymers because of its attributes. It is classed as a synthetic rubber but it is unique as it is gas impermeable which means gas can’t pass through it. it’s the only rubber that can hold air for long periods of time. Balloons are made from polyisoprene, which is not gas impermeable. Because polyisobutylene will hold air, it is used to make things like the inner liner of tires, to ensure gas doesnt escape. The structure is 2 carbons connected with a double bond with one carbon connected to 2 hydrogen and the other connected to 2 methyl groups(Ch3) and once polymerised the double bonds break but the structure remains the same.

    The polymerisation is carried out at around -100*C, this is because the reaction is too fast if it isn’t frozen. If its too fast it is uncontrollable and unpredictable results would occur. They are used in engines to keep sludge, soot and any other deposits from forming deposits onto and harming key engine parts.
    The remainders can be used as catalysts in a range of different reactions including additions and allyic reactions but can also be reagents in mitsonobu reactions. All the remainders can be re-used so is an environmental friendly polymer.

    file:///home/chronos/u-bcd051a441685254d10800749ccae87e7b424b8b/Downloads/Polyisobutylene_ProductStewardshipSummary.pdf

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  5. Polyvinyl chloride- (PVC)
    Addition polymer:

    PVC (Chloroethene). Chloroethene is made from reacting ethylene with oxygen and hydrogen chloride over a copper catalyst. It is a toxic and carcinogenic gas that is handled under special protective procedures. PVC is made by subjecting vinyl chloride to highly reactive compounds known as free-radical initiators. Under the action of the initiators, the double bond in the vinyl chloride monomers (single-unit molecules) is opened, and one of the resultant single bonds is used to link together thousands of vinyl chloride monomers to form the repeating units of polymers (large, multiple-unit molecules). The chemical structure of the vinyl chloride repeating unit

    Chemical stability is a common feature among substances containing halogens such as chlorine and fluorine. This applies to PVC resins, which furthermore possess fire retarding properties, durability, and oil/chemical resistance. Due to the chlorine attached to the compound it means that the ignition temperature of PVC is approximately 455°C and is also a material with less risk for fire incidents since it does not ignited easily. Furthermore PVC is very durable because it is highly resistant to oxidation from atmospheric oxygen. It is very resistant to oxidation because it has a molecular structure whereby the chlorine atom is bound to every other carbon chain- this maintains its performance for a very long time.

    Polyvinyl chloride (PVC) is one of the most used plastics in the world. Global PVCuse exceeds 35 million tonnes per year, and the demand is growing. At a global level, PVC use grows by an average of 5% per year, with higher growth rates in developing countries.

    If PVC were to be dumped into landfill, they would last for hundreds of years without degrading at all. PVC compounds are 100% recyclable physically, chemically or energetically. After mechanical separation, grinding, washing and treatment to eliminate impurities, it is reprocessed using various techniques (granulated or powder) and reused in the production.
    There are two principal ways of recycling PVC:
    Mechanical recycling: PVC waste is ground into small pieces that can be easily processed into new PVC compounds ready to be melted and formed into new products.
    Feedstock recycling: PVC waste is broken right back down into its chemical molecules, which can be used again to make PVC or other materials.

    Bibliography:
    http://www.pvc.org/en/p/pvcs-physical-properties
    http://www.britannica.com/science/polyvinyl-chloride

    Jonathan Totty

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  6. The life of a Polymer- Polytetrafluroethene

    Polytetrafluroethene (Teflon or PTFE), comes from the polymerisation of the monomer tetrafluroethene (TFE)- CF2=CF2.

    F F F F

    n C=C —> ——- C-C——-

    F F F F n

    (Fluorines should be bonded to carbons, and PTFE should have brackets around)

    It was first created, accidently, by Dr Roy Plunkett. He was experimenting with TFE as a potential alternative refrigerant, and froze in it small gas cylinders. When he came to open the cylinders, nothing came out, despite it still feeling full. He discovered that the TFE had polymerised into a white waxy powder, now known as Teflon. He proceeded to run tests on this new substance, discovering it was very slippery, non-corrosive, chemically stable and had an extremely high melting point. These properties were deemed interesting, and further tests were done.

    Teflon it still is the only known substance that a gecko’s feet cannot stick to, because of its resistance to van der Waals forces. Molecularly, Teflon is one of the largest molecules known to man and consists of carbon and fluorine. Each carbon atom has two fluorine atoms attached. When fluorine is part of a molecule, it actually repels other matter, which is why the gecko’s feet cannot stick to it. The bond between the fluorine and carbon is also extremely strong which makes Teflon very non-reactive to other chemicals.

    Today, Teflon is best known for being used as a coating for non-stick pans. However it is also used in windshield wipers, as a stain repellant for carpets and furniture, and for insulation for wires, among other things.

    Recycling of PTFE became common in industries, as there is no chemical reaction is required. The PTFE scrap is grinded into a fine powder and then blended with pure PTFE that is used in compressions molding. To remove the inorganic compounds the scrap is first heated before grinding. Next it is put into a long strand, which is then cut down into small pallets and sent to industries that use recycled material for their products. The powder is used in inks, paints and cosmetics. It is also useful for fiber filling for ski coats, fleece coat, and polyester suits. PTFE recycling reduces greenhouse gas emissions and save the environment. It’s even used for making plastic lumber, toys, park benches, car parts, drainage pipes and more.

    References-
    http://www.ausetute.com.au/polymers.html
    http://www.todayifoundout.com/index.php/2011/08/teflon-was-invented-by-accident/
    http://www.ptferecycling.com/ptfe-recycling-facts/

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  7. The life of a Polymer- Polytetrafluroethene

    Polytetrafluroethene (Teflon or PTFE), comes from the polymerisation of the monomer tetrafluroethene (TFE)- CF2=CF2

    https://www.google.co.uk/url?sa=i&rct=j&q=&esrc=s&source=images&cd=&ved=0ahUKEwjE4qHKoaTLAhURb5oKHUCYACsQjRwIBw&url=http%3A%2F%2Fwww.docbrown.info%2Fpage04%2FOilProducts07.htm&psig=AFQjCNEswo9AMhSq66qE4477XYxLCDfzGg&ust=1457085756238524

    It was first created, accidently, by Dr Roy Plunkett. He was experimenting with TFE as a potential alternative refrigerant, and froze in it small gas cylinders. When he came to open the cylinders, nothing came out, despite it still feeling full. He discovered that the TFE had polymerised into a white waxy powder, now known as Teflon. He proceeded to run tests on this new substance, discovering it was very slippery, non-corrosive, chemically stable and had an extremely high melting point. These properties were deemed interesting, and further tests were done.

    Teflon it still is the only known substance that a gecko’s feet cannot stick to, because of its resistance to van der Waals forces. Molecularly, Teflon is one of the largest molecules known to man and consists of carbon and fluorine. Each carbon atom has two fluorine atoms attached. When fluorine is part of a molecule, it actually repels other matter, which is why the gecko’s feet cannot stick to it. The bond between the fluorine and carbon is also extremely strong which makes Teflon very non-reactive to other chemicals.

    Today, Teflon is best known for being used as a coating for non-stick pans. However it is also used in windshield wipers, as a stain repellant for carpets and furniture, and for insulation for wires, among other things.

    Recycling of PTFE became common in industries, as there is no chemical reaction is required. The PTFE scrap is grinded into a fine powder and then blended with pure PTFE that is used in compressions molding. To remove the inorganic compounds the scrap is first heated before grinding. Next it is put into a long strand, which is then cut down into small pallets and sent to industries that use recycled material for their products. The powder is used in inks, paints and cosmetics. It is also useful for fiber filling for ski coats, fleece coat, and polyester suits. PTFE recycling reduces greenhouse gas emissions and save the environment. It’s even used for making plastic lumber, toys, park benches, car parts, drainage pipes and more.

    References-
    http://www.ausetute.com.au/polymers.html
    http://www.todayifoundout.com/index.php/2011/08/teflon-was-invented-by-accident/
    http://www.ptferecycling.com/ptfe-recycling-facts/

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  8. Natural Rubber – poly (cis-1,4-isoprene)

    Synthesis-

    Polyisoprene can be created synthetically, producing what is sometimes referred to as “synthetic natural rubber”, but the synthetic and natural routes are completely different.

    Uses-
    Around 25 million tonnes of rubber is produced each year, of which 42 per cent is natural rubber. The remainder is synthetic rubber derived from petrochemical sources. Around 70 per cent of the world’s natural rubber is used in tires. The top end of latex production results in latex products such as surgeons’ gloves, condoms, balloons and other relatively high-value products

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