Polymers Flashcards
What is condensation polymerization?
It usually involves two different types of monomers, each with at least two functional groups. Each functional group reacts with a group on another monomer to form a link, creating polymer chains.
Each time a link is formed a small molecule of water is lost.
What are some examples of condensation polymers?
- Polypeptides
- Polyamides
- Polyesters
How are polyamides formed?
The carboxyl groups of dicarboxylic acids react with the amino groups of Diamines to form amide links. Dicarboxylic acids and Diamines have functional groups at the end of the molecule so long chains can form.
What is nylon and how is it formed?
Nylon 6,6 is a polyamide made from 1,6-diaminohexane and hexanedioic acid. It is used to make clothing, carpets, rope, airbags, and parachutes.
What is kevlar and how is it formed?
Kevlar is a polyamide made from 1,4- diaminobenzene and benzene-1,4 dicarboxylic acid. It is used in bulletproof vests, boat construction, car tyres, and lightweight sports equipment.
How do you make polyesters?
The carboxyl groups of dicarboxylic acids can react with the hydroxyl groups of diols to form ester links. Polymers joined by ester links are called polyesters.
What is Terylene (PET) and how is it formed?
Terylene (PET)- formed from benzene- 1,4-dicarboxylic acid and ethane-1,2-diol. It’s used in plastic bottles, clothing, sheets and sails.
How can you get monomers from a condensation polymer?
Condensation polymerization can be reversed by hydrolysis- water molecules are added back in and the links are broken.
Why are condensation polymers stronger and more rigid than addition polymers?
- Condensation polymers are made up of chains containing polar bonds. So, as well as Van der Waals forces, there are permanent dipole-dipole forces and hydrogen bonds between the polymer chains.
What are polyalkenes? (pros and cons)
They are addition polymers. They are made up of non-polar carbon chains, which makes them unreactive and chemically inert.
so they won’t react when used: e.g. with coffee in a coffee cup
but it does mean they won’t biodegrade so they will end up in landfills and produce toxic gas when burnt
What are condensation polymers? (pros and cons)
Condensation polymers such as polyesters and polyamides do have polar bonds in their chains, which makes them open to attack by nucleophiles.
This means that condensation polymers can be broken down by hydrolysis so these polymers are biodegradable, although the process is very slow.
What are the Pros and Cons of burying waste plastics?
- A landfill is used when the plastic is difficult to separate, hard to recycle, and not in sufficient quantities to make separation viable.
- Landfill is cheap and easy but does require areas of land
- When the waste decomposes it can release methane- a greenhouse gas. Leaks can also contaminate water supplies
What are the Pros and Cons of burning waste plastics?
- waste plastics can be burned and the heat used to produce electricity
- This process needs to be carefully controlled as it causes the release of toxic gases.
- so waste gases from the combustion are passed through scrubbers which can neutralize gases by reacting them with a base but the waste gases like CO2 will still contribute to the greenhouse gases.
What are the advantages of recycling waste plastics?
- It reduces the amount of waste going into landfill
- It saves raw materials- which is important because oil is non-renewable
- The cost of recycling plastics is lower than making the plastics from scratch
- It produces less CO2 emissions than burning the plastics
What are the disadvantages of recycling waste plastics?
- It is technically difficult to recycle plastics
- Collecting, sorting, and processing the plastic is more expensive than burning/landfill
- You often can’t remake the plastic you started with- you have to make something else.
- The plastic can be easily contaminated during the recycling process.
