Polymers

Question 1

3 main types of condensation polymers

Answer 1

Polypeptides - found in proteins
Polyamides - formed from diamines and dicarboxylic acids
Polyesters - formed from diol and dicarboxylic acid

Question 2

What is condensation polymerisation?

Answer 2

2 different monomers with at least 2 functional groups react together, eliminating a water molecule

A link is made, which determines the type of polymer produced

Question 3

Examples of polyamide

Answer 3

Kevlar
-made from benzene-1,4-dicarboxylic acid and 1,4-diaminobenzene
-used in bulletproof vests, car tyres and some sports equipment
-lightweight but strong

Nylon 6,6
-made from hexanedioic acid and 1,6-diaminohexane
-used in ropes, carpets, clothing and parachute fabric

Question 4

Examples of polyesters

Answer 4

Terylene (PET)
-made from benzene-1,4-dicarboxylic acid and ethane-1,2-diol
-used in plastic drinks bottles, sheeting and clothes

Question 5

Reverse of condensation polymerisation

Answer 5

Hydrolysis

Question 6

Polarity in condensation polymers

Answer 6

-have polar bonds (C-O and C-N)
-usually more rigid and stronger than in addition polymers
-hydrogen bonds exist between polymer chains, as well as dipole-dipole and Van der Waals forces
-makes condensation polymers stronger than addition polymers

Question 7

Synthetic polymers

Answer 7

-made from monomer units
-uses include plastic bottles, digital technology, non-stick coatings on pans, etc

-condensation polymers are polar = susceptible to attack from nucleophiles
-hence biodegradable and hydrolysis slowly breaks them down
-polyalkenes are saturated addition polymers
-normally non-polar, so don’t degrade well

Question 8

Landfill is useful for disposing of plastics that…

Answer 8

-are too difficult to recycle
-are too difficult to separate from other materials
-there is not enough of to extract to make it economically viable

Question 9

Risks of waste decomposition in landfill

Answer 9

-produces methane (greenhouse gas)
-also water contamination from waste leaching
-hence landfill is not very sustainable
-very expensive so there is a need to reduce reliance on it

Question 10

Incineration

Answer 10

-burning waste plastics that can’t be recycled
-energy from burning can be used to generate electricity

-however, release toxic fumes
-e.g. PVC produces acidic HCl gas
-flue gas scrubbers are used to neutralise it by firing a base at it

Question 11

Recycling plastics

Answer 11

-most plastics are made from crude oil (non-renewable)
-reduces dependency on crude oil
-some plastics can be re-moulded into new objects
-others can be cracked into monomers which can be used as organic feedstock for plastics or other substances

Pros:
-reduces reliance on landfill
-preserves non-renewable raw materials, e.g. crude oil
-cheaper to recycle than make plastics from scratch
-less CO2 is produced than incinerating

Cons:
-plastics can be contaminated with other materials
-difficult to recycle due to wide variety of different plastics
-difficult to re-make original plastic from recycled material
-sorting and processing plastics to be recycled is more expensive than incineration