Polymer PowerPoint 1

• Polymers


  Very large covalent molecules (plastics)
• Polymers


  • Cheap
  • Versatile
  • Easy to manufacture
• Monomers


  Individual units that make up polymers
• Polymerisation


  1. Addition polymerisation

  2. Condensation polymerisation
• Types of Polymers


  • Linear (thermoplastic)
  • Cross-linked (thermosetting)
• Polymer properties


  • Chain length
  • Monomer
  • Branching
  • Crystalline areas
  • Plasticisers
• Polymers are a threat to the environment, but recycling and a circular economy can help
• Addition polymerisation


  Reaction of an alkane with another molecule, can also undergo addition reactions with themselves to produce long chains
• Addition polymerisation


  • Ethene becomes polyethene
• Addition polymerisation


  • Bromoethane is a specialty polymer used when a flame-resistant polymer is required
• Addition polymerisation


  • Polypropene is manufactured in Australia and has a wide range of uses
• Condensation polymerisation


  Use polymers with functional groups on either end, the monomers join together when the functional groups interact
• Condensation polymers


  • Nylon
  • Cellulose (found in plant materials)
  • Chitin (found in fungi, crustaceans and insects)
• Condensation polymerisation occurs naturally in organisms
• Plasticisers


  Small molecules that can be added to polymers during manufacture
• Plasticisers


  • Polymers are forced slightly further apart weakening intermolecular bonding
  • Causes plastic to be softer and more flexible
• Copolymers


  Mixed polymers made by reacting two or more different monomers
• Copolymers help combine the properties of different polymers and gives a more versatile product
• Presence of dipole-dipole attractions in copolymer


  Increases strength and/or solubility in water
• Chain Length


  The length of the chain determines the amount of dispersion forces present
• Higher dispersion forces


  Causes higher melting (and boiling) points
• Properties of polymers


  • Tensile strength
  • Softening temperature
  • Transparency/Opaque
  • Hardness/toughness/durability
• Factors affecting polymer properties


  • Choice of Monomer
  • Degree of branching
  • Nature of side groups
  • Arrangement of side groups
  • Chain length
  • Copolymers
  • Foamed Polymers
  • Plasticisers
• Isotactic


  Side groups on the same side
• Syndiotactic


  Side groups alternate which side they are on
• Atactic


  Side groups are random
• Nature of Side Groups


  • Less dispersion forces
  • Only dispersion forces present as monomer is non-polar
  • Presence of dipole-dipole attractions (less than Teflon though)
  • Presence of dipole-dipole attractions
  • Presence of hydrogen bonding
• High degree of branching


  Less dispersion forces, low density, softer and more flexible
• Low degree of branching


  More dispersion forces, high density, stronger and less flexible
• Types of Polymers


  • Linear (thermoplastic)
  • Cross-linked (thermosetting)
• Features of polymers

  • Chain length
  • Monomer
  • Branching
  • Crystalline areas
  • Plasticisers
• Mechanical recycling - unfortunately, this process can only be applied a few times because the quality of the plastic is degraded each time as the length of the polymer chains is shortened.
• Biobased


  The material or product is at least partly derived from biomass such as plants
• Biodegradable


  Biodegradation is a chemical process during which micro-organisms convert materials into natural substances, such as water, carbon dioxide and compost
• Compostable


  A product that is capable of disintegrating into natural elements in a compost environment, leaving no toxicity to the soil
• Biopolyethene


  Can be made from various raw materials including sugar cane, sugar beet and wheat grain, so it is a renewable resource. It also reduces greenhouse gas emissions because it removes carbon dioxide from the atmosphere. However, it is not biodegradable and cannot be composted.
• Biopropene


  A thermoplastic with similar properties to bioethene but it is harder and more resistant to heat. It is also recycled similarly.
• Biopolyethene (bio-PE) and biopolypropene (bio-PP) are chemically identical to their crude oil sourced counterparts, and as such are also not biodegradable.
• Condensation polymers


  More likely to be compostable compared to addition polymers as the presence of polar C=O (carbonyl) bonds allows for microorganisms to attack and break up polymers into their monomers
• In 2016 Japanese scientists discovered a bacteria that was breaking plastic at 6 times the normal rate. They isolated an enzyme which they called PETase and it breaks the condensation polymer into its monomers again.