Polymers Flashcards
What is condensation polymerisation?
Usually involves two different types of monomer, each of which normally has two functional groups. Each functional group reacts with a group on another monomer to form a lime creating polymer chains and a small molecule is lost
What are the 3 common types of condensation polymers?
Polyamides, polyesters and polypeptides
What are polyamides?
Monomers: dicarboxylic acids and diamines
Bond between monomers: amide link (-CONH-)
What is Nylon 6,6 ?
Made from 1,6 diaminohexane and hexanedioic acid
Strong and resistant to abrasion so used to make carpet, clothing, rope, airbags and parachutes
What is Kevlar?
Made from benzene 1,4 dicarboxyic acid and 1,4 diaminobenzene
Light and very string so used in bulletproof vests, boat construction, car tyres and lightweight sports equipment
What are peptides?
Proteins. Made from amino acids, which have a carboxylic acid group and an amine group.
What are polyesters?
Monomers: dicarboxylic acids and diols
Bond between monomers: ester link (-COO-)
What is Terylene (PET)?
Formed from benzene 1,4 dicarboxylic acid and ethane-1,2-diol
Some forms stable at both hot and cold temps, so useful for creating containers for ready meals. Other forms used for plastic bottles, sheets, sails and clothing
How are polyesters and polyamides broken down?
By hydrolysis- water molecules added back in
What is used in the lab instead of water to speed up?
Acids for polyamides and alkalis for polyesters
Why are condensation polymers typically stronger and more rigid than addition polymers?
Made up of chains containing polar bonds e.g. C=O and C-N or C-O
This means there are permanent dipole-dipole forces and very strong hydrogen bonds between polymer chains
Why are polyalkenes not biodegradable, but condensation polymers are?
Polyalkenes are chemically inert as they have non polar bonds and so arent susceptible to attack by nucleophiles, so the bonds cant be hydrolysed and naturally broken down.
Condensation polymers have polar bonds between repeating units and so can be broken down by hydrolysis and therefore are biodegradable
What are the advantages and disadvantages of burying plastic waste?
+: relatively cheap and easy method of waste disposal
-: requires areas of lands, as the waste decomposes it can release methane and toxins which can be washed away and contaminate water supplies
What are the disadvantages of burning waste plastic?
Toxic gases produced so need to be removed by being passed through scrubbers to neutralise gases by allowing them to react with a base. However, the waste gases will still contribute to the green house effect
What are the advantages of recycling?
Reduces waste going to landfill, saves raw materials (important as oil is non renewable), costs less than making from scratch, produces less CO2 than burning plastic
What are the disadvantages of recycling?
Technically difficult, more expensive to collect and sort and process than burning/landfill, often can’t remake the plastic you start with, plastic can be easily contaminated
