Polymers (A-level only) Flashcards
What 3 polymers make up condensation polymers?
Polypeptides
Polyamides
Polyesters
Describe condensation polymerisation..
Condensation polymerisation is where 2 different monomers with at least 2 functional groups react together. A link is made and water is eliminated.
How is a polyamide produced?
By reacting dicarboxylic acids and diamines together.
An amide links are formed.
OH is always lost from the carboxylic acid
Hydrogen is lost from the amine
(elimination of water)
Describe kevlar and its formation
Kevlar is a polyamide that is used in bulletproof vests, car tyres and sports equipment due to its light weight but strong properties.
REACTANTS:
Benzene-1,4-dicarboxylic acid
1,4-diaminobenzene
Describe Nylon 6,6 and its formation
Nylon 6,6 is a polyamide that is used in ropes, carpets, clothing.
REACTANTS:
hexanedioic acid
1,6-diaminohexane
How are polyesters formed?
REACTANTS:
dicarboxylic acids
Diols
Ester links formed
Describe Terylene and its formation..
It is a polyester that is used in plastic drinks bottles, sheeting and clothes.
REACTANTS:
benzene-1,4-dicarboxylic acid
ethane-1,2-diol.
What is hydrolysis?
Condensation polymers can be hydrolysed (split using water) to produce the original monomers.
Describe polarity in condensation polymers?
They have polar bonds caused by c-o and c-n bonds.
This makes the condensation polymers more rigid and stronger than their addition polymer counterparts.
Condensation polymers have polar bonds and these chains interact with each other.
Describe intermolecular bonding in condensation polymers..
Hydrogen bonds exist between the polymer chains as well as diapole-diapole and VDW forces. This makes condensation polymers stronger than addition polymers.
What are uses of polymers?
Synthetic polymers- plastic bottles, digital tech, non-stick coatings on pans
Are condensation polymers biodegradable?
Yes they are as they are polar so are susceptible to attack from nucleophiles. So they are biodegradable and can be broken down by hydrolysis slowly.
Are addition polymers (polythene eg.) biodegradable?
No as they are saturated molecules they are normally non-polar and are hence unreactive. The c-c bonds are strong.They don’t degrade well in landfill.
How are landfills used to dispose of plastics (use of polymers)? + usefulness
Most polymers are not biodegradable.
+:
Useful in disposing plastics that are:
- too difficult to recycle
- Are too difficult to separate from other materials
- There is not enough plastic to extract to make it economically viable
- :
- When waste decomposes in landfill it produces methane which is greenhouse gas. There is also a risk of water contamination from waste leaching.
- Landfill is not very sustainable as large amounts of land is needed.
It is becoming increasingly expensive to use land for waste disposal and there is a need to reduce our reliance on landfill.
How is incineration (burning) waste plastics as a method? + usefulness
+)
- Incineration (burning) waste plastics could be used if the plastics can’t be recycled. The energy from burning it can be used to generate electricity.
-)
- Burning plastics can release toxic fumes so these need to monitored.
Particularly chlorine based plastics like PVC which produce harmful HCl
gas when burned.
-Flue gas scrubbers are used to neutralise acidic gases produced like HCl. They work by firing a base at the flue gases.
How is recycling as a method of disposing plastics?
Most plastics are made from crude oil which is a non-renewable source.
Recycling means reducing dependency on crude oil for making plastics.
Other plastics can be cracked (polymer chain broken up) into monomers to be used as an organic feedstock for plastics or other substances
Some plastics like poly (propene) can be re-moulded into new objects.
What are the advantages of recycling plastics?
It is cheaper to recycle plastics than make them from scratch.
Less carbon dioxide is produced recycling plastics than incinerating them.
Recycling reduces the reliance on landfill
Recycling preserves non renewable raw materials
such as crude oil
What are the disadvantages of recycling plastics?
Plastics can be contaminated with other materials when being recycled.
It is difficult to recycle plastics due to the wide variety of different plastics
It is difficult to re-make the original plastic from recycled material
Sorting and processing plastics to be recycled is expensive compared with incineration.
