polymers

• what are polymers ?

  they are very large organic molecules built up from many small units called monomers
• what is polymerisation ?

  it is the process of joining together a large number of monomers to form a polymer
• what bonds are monomers in a polymer joined by ?

  covalent bonds
• addition polymerisation occurs when unsaturated monomers join together without losing any molecules or atoms to form addition polymers
• what does the addition polymerisation of ethene monomers produce ?

  poly(ethene)
• describe the process of addition polymerisation of ethene

  • at high temperature and pressure, and in the presence of a catalyst, the carbon- carbon double bonds of the ethene molecules break
  • each monomer forms single bonds with 2 other monomers and eventually poly(ethene) is formed
• what is the repeating unit of poly(ethene) ?

  -(CH2-CH2)-

  
• what are some uses of addition polymers ?

  • poly(ethene)
  • easily moulded into various shapes to be used to make plastic bags, cling wraps and plastic toys
  • polyvinyl chloride
  • make thing gloves, pipes and raincoats
  • polystyrene
  • is hard, light and brittle to be used to make disposable containers
  • polytetrafluoroethylene
  • used to coat frying pans as it is heat resistant and had non- stick properties
• what is condensation polymerisation ?

  it is when monomers combine to form condensation polymers with the removal of smaller molecules such as water
• what are the 2 main groups of condensation polymers ?

  polyamides and polyesters
• what monomers react to form nylon ?

  dicarboxylic acid and diamine
• what monomer is this ?

  dicarboxylic acid

  
• what monomer is this ?

  diamine

  
• what molecule is formed from each pair of dicarboxylic and diamine monomers ?

  water
• what linkage joins the monomers in nylon ?

  amide linkages
• where does each atom of water derive from making nylon ?

  OH from dicarboxylic acid and H from diamine
• what linkage is this and is found in which polymer ?

  amide linkage, found in polyamide

  
• what 2 monomers react to form terylene ?

  dicarboxylic acid and diol
• what monomer is this ?

  diol

  
• what linkage joins the monomers in terylene ?

  ester linkage
• what linkage is this and is found in what polymer ?

  ester linkage, found in polyester

  
• what are the monomers of polyamides ?

  dicarboxylic acid and diamine
• what are the monomers of polyester ?

  dicarboxylic acid and diol
• dicarboxylic contains what functional groups ?

  2 carboxylic acid groups (-COOH)
• amide contains what functional groups ?

  2 alcohol groups (-OH)
• what are some uses of synthetic fibres ?

  • fishing lines
  • strong, can be drawn into long thin strands without breaking
  • clothes
  • shrink- proof and crease- proof
  • easier to wash and dry
  • tent and sleeping bags
  • do not shrink when exposed to water
• why are plastics being used in place of natural materials ?

  • relatively cheap
  • easily moulded into various shapes
  • light, tough and waterproof
  • durable
• what are the disadvantages of plastics ?

  • land pollution
  • water pollution
  • air pollution
• what does pre- treatment of plastic waste involve ?

  • sorting by different methods
  • washing to remove contaminants
  • shredding or grinding to smaller pieces
• what is the process of the physical method of recycling plastics ?

  1. small pieces of plastics are melted and cooled
  2. they are then pulled into long, thin strands and cut into pellets which can be made into new products
• what is the process of chemical method of recycling plastics ?


  • cracking
  • plastic waste undergo cracking to form short chains of alkanes and alkenes
  • the short chain alkanes can be used as fuel
  • the short chain alkenes can be used to make other useful chemicals
  • depolymerisation
  • polymer is converted back into its monomers
  • the monomers can be converted to other useful chemical
• what is depolymerisation ?

  a process where polymers are broken down into their monomers
• how can polyesters undergo depolymerisation ?

  through acid hydrolysis where the polyester is broken down using water in the presence of an aicd catalyst
• what are the environmental issue related to recycling plastics ?

  • physical and chemical methods lead to environmental issues
  • if wastewater generated from the recycling process is not treated properly before being discharged into water bodies, it can contaminate the water and cause water pollution
• what are the economic issue related to recycling plastics ?

  • high costs
  • cost of transporting waste to the processing plant
  • cost of sorting and cleaning the waste and carrying out the recycling process
  • they require manpower, machines and energy
  • not economically viable or worthwhile if the cost of recycling plastics waste are higher than the value of recycled plastics
  • recycled plastics have a lower market value than virgin plastics
  • difficult for recycling businesses to survive if the cost of recycling plastic waste is too high
• what are the social issue related to recycling plastics ?

  • people find it more convenient to throw their waste away rather than recycling
  • people are not aware of how to properly recycle plastics and hence is not carried out properly
  • recyclable items are contaminated with leftover food
  • non- recyclable items are thrown in recycling bins, increasing the time and effort to separate recyclables from waste, slowing down the recycling process
  • takes time and effort for communities to adopt recycling as a lifestyle so it may not be immediately effective
• how can we address the issues related to recycling plastics ?

  • strict measures and laws put in place to minimise potential environmental issues
  • recycling programmes introduced to educate the public on the correct way to recycle
  • creative activities to encourage people to practise recycling