Biodegradability & Disposal of Polymers
Polyalkenes such as poly(ethene) and polystyrene are chemically inert - not reactive. This is
because the bonds between the repeating units are non polar so are not susceptible to attack
from nucleophiles.
Being chemically inert is a useful property because it means the polymer will not react with its
surroundings. However, it also means that they are non biodegradable and therefore the bonds
in the polymer will not break down naturally.
Condensation polymers such as PET can be broken down by hydrolysis because the
bonds in between the repeating units are polar so can be attacked from nucleophiles such
as water. Because the bonds in condensation polymers are polar they can be hydrolysed
and therefore the polymers are biodegradable - which means they will break down
naturally but the process is very slow.
Burying Waste Plastic
Usually used when plastic is difficult to separate from other waste
+Cheap and Easy Method
-Requires a lot of land
-As the waste decomposes it released methane - a greenhouse gas
-As waste decomposes it can release toxins which can be washed away and contaminates
water supplies
Burning Waste Plastic
Waste plastics are burnt and the heat is used to generate electricity
-Process needs to be carefully controlled to reduce toxic gases
-HCl produced when burnt is toxic
-Waste gases must be passed through scrubbers which neutralises gases
-Contributes to greenhouse effect
Recycling Plastics
Many plastics are made from non-renewable oil fractions - plastics are then sorted,
melted and remoulded
Polyalkenes such as poly(ethene) and polystyrene are chemically inert - not reactive. This is
because the bonds between the repeating units are non polar so are not susceptible to attack
from nucleophiles.
Being chemically inert is a useful property because it means the polymer will not react with its
surroundings. However, it also means that they are non biodegradable and therefore the bonds
in the polymer will not break down naturally.
Condensation polymers such as PET can be broken down by hydrolysis because the
bonds in between the repeating units are polar so can be attacked from nucleophiles such
as water. Because the bonds in condensation polymers are polar they can be hydrolysed
and therefore the polymers are biodegradable - which means they will break down
naturally but the process is very slow.
Burying Waste Plastic
Usually used when plastic is difficult to separate from other waste
+Cheap and Easy Method
-Requires a lot of land
-As the waste decomposes it released methane - a greenhouse gas
-As waste decomposes it can release toxins which can be washed away and contaminates
water supplies
Burning Waste Plastic
Waste plastics are burnt and the heat is used to generate electricity
-Process needs to be carefully controlled to reduce toxic gases
-HCl produced when burnt is toxic
-Waste gases must be passed through scrubbers which neutralises gases
-Contributes to greenhouse effect
Recycling Plastics
Many plastics are made from non-renewable oil fractions - plastics are then sorted,
melted and remoulded
