Polymers

• An addition reaction breaks a double bond.
• Polymers are long-chained molecules with large molecular masses that are made from many short-chained molecules called monomers added together via addition polymerisation.
• Monomers involved in addition polymerisation are always alkenes.
• In addition polymerisation, the alkenes add together across the C=C bond where the pi bond breaks, producing saturated long chain molecules.
• Chloroethene becomes poly(chloroethene).
• One repeat unit only has two carbon atoms.
• A repeat unit is the smallest group of atoms that when connected one after the other make up the polymer chain.
• A repeat unit is represented by square brackets in the displayed formula.
• Repeat units do not have double bonds.
• Polymers are burnt for energy.
• Polymers are unreactive.
• Polymers are not biodegradable.
• Recycling reduces the environmental impact of polymers, as it decreases the amount of waste going to landfills.
• The high chlorine content of PVC makes the disposal and recycling of it hazardous.
• Why is burning PVC as a method of disposal hazardous?


  The high chlorine content means it will release hazardous HCl when burnt.
• New technology uses a solvent to dissolve PVC, which is then recovered by precipitation from the solvent and it can be used again.
• Feedstock recycling is a chemical and thermal process that reclaims monomers, gases, or oil form waste polymers, which are then used to produce new polymers.
• Biodegradable polymers are broken down by microorganisms into water, carbon dioxide, and biological compounds.
• Biodegradable polymers are usually made from starch/cellulose.
• The low reactivity of polymers makes them ideal for uses such as food packaging.
• The recycling of polymers can reduce the use of finite resources as lots of polymers are made from the products of cracking crude oil and its fractions.
• Recycling polymers is a time-consuming process as they have to be sorted into the different categories.
• Combusting polymers under controlled conditions can produce heat energy which can then be used to generate electricity.
• Since they have a large amount of energy stored within the polymer chains, these polymers can be incinerated. This process can then be used to boil water and use the water vapour to turn turbines inside a power station.
• Burning polymers causes environmental pollution as the carbon within the polymer can be released as carbon dioxide, contributing to global warming.
• Feedstock recycling is where waste polymers are broken down by chemical and thermal processes into monomers, gases, and oils.
• The major benefit of feedstock recycling is that it works with unsorted and unwashed poymers.
• Photodegradable polymers contain bonds that are weaking by absorbing light/visible raditation, starting the breakdown of the polymer.
• A lot of photodegradable polymers are oil based.
• In certain cases, an additive that absorbs light is mixed into the polymer to promote degradation.
• State one uses of poly(chloroethene) 'PVC'.


  Window frames.
• State one use of poly(propene).


  Carpet fibres.
• State 2 disadvantages of PVC.

  1. It is not biodegradable.
  2. It releases toxic gases (HCl) when burned.
• Describe how scientists are working to overcome the problems with polymers.


  1. Burning as a fuel source for energy
  2. Sorting and remoulding
  3. Feedstock recycling
• State 3 methods of disposing of polymers that can be beneficial to the environment.


  1. Recycling
  2. Combustion for energy production
  3. Feedstock recycling to produce organic products