4837778
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Mind Map by Bee Brittain, updated more than 1 year ago
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Created by Bee Brittain
about 8 years ago
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13.5 Polymerisation in Alkenes
- Polymer
- Large molecules formed from
many thousands of smaller,
individual repeat units known as
monomers
- Large molecules formed from
many thousands of smaller,
individual repeat units known as
monomers
- Unsaturated Alkenes go through ADDITION POLYMERISATION
- produces long, saturated chains
- Addition polymers have high molecular masses
- synthetic polymers are usually named after the monomer, prefixed by 'poly'
- Repeat unit is the specific arrangement of atoms in the polymer molecule
- produces long, saturated chains
- Enviromental Concerns
- Most alkene-based polymers are non-biodegradeable!
- Waste plastics can be BURIED
- However the sheer amount of waste we produce is becoming a problem so land fill needs to be reduced
- When they are difficult to
separate from other plastics
- When they are not in
sufficient quantities
to make separation
worth while
- When it is too technically difficult to recycle
- However the sheer amount of waste we produce is becoming a problem so land fill needs to be reduced
- Waste plastics can be REUSED
- Many plastics are made from non-renewable oil-fractions = reuse as much as possible
- After SORTING:
- Some plastics (e.g polypropene) can be
recycled by melting and remoulding
them
- Some plastics can be cracked back into their
monomers and used as ORGANIC FEEDSTOCK to
make more plastics and chemicals
- Feedstock recycling is good as it is able to handle unsorted and unwashed polymers
- Feedstock recycling is good as it is able to handle unsorted and unwashed polymers
- Some plastics (e.g polypropene) can be
recycled by melting and remoulding
them
- Many plastics are made from non-renewable oil-fractions = reuse as much as possible
- Waste plastics can be BURNED
- Heat can be used to generate electricity
- Process needs to be carefully controlled to reduce TOXIC GASES.
- For example, when a polymer that contains Cl is burned, it
releases HCl, which has to be removed
- Waste gases pass through scrubbers which can neutralise
gases such as HCl by allowing them to react with a base
- Waste gases pass through scrubbers which can neutralise
gases such as HCl by allowing them to react with a base
- For example, when a polymer that contains Cl is burned, it
releases HCl, which has to be removed
- Heat can be used to generate electricity
- Most alkene-based polymers are non-biodegradeable!
- Biodegradable and photodegradable polymers
- Biodegradable polymers decompose quickly in certain conditions as organisms can digest them
- Can be made from renewable sources such as starch, cellulose,
plant oils, proteins or oil fractions, such as from the hydrocarbon
isoprene
- However these are more expensive then their non-biodegradable equivalents
- However these are more expensive then their non-biodegradable equivalents
- Require right conditions - compost heap
- Need collecting and seperating from non-biodegradable polymers
- Potential uses - e.g/ plastic sheeting used to protect
plants from frost - contains starch grains embedded
into it so that the starch is broken down by
microorganisms and remaining polyethene
crumbles to dust over time
- Photodegradable polymers degrade when exposed to sunlight
- Biodegradable polymers decompose quickly in certain conditions as organisms can digest them
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