polymerisation Flashcards
what are condensation polymers
they form when a water molecule is removed from the species of a reaction
what are the three main types of condensation polymers
- polyamide
- polyesters
- polypeptides
how are polyamides formed
in a reaction between diarboxylic acid and a diamine. a moleucle of water is removed leaving an amide linkage (-CONH-)
features of polyamides
normally formed from long chain molecules, which provides them with strength
examples of polyamides
- nylon - 6,6 - made from hexamethlyenediamine and hexandioic acid
- Kelvar - made from 1,4-benzendicarboylic acid and 1,4-benzenediamine
how are polyesters formed
are formed in a reaction between dicarboxylic acids and a diol, producing an ester linkage (-COO-)
example of a polyester
Terylene (PET) - made from ethanediol and 1,4-benzenedicarboxylic acid
polypeptides
formed from multiple amino acids. A single monomer can produce a polymer due to the presence of both a -NH and -OH group. peptide linkage (-CONH-)
hydrolysis
Condensation polymers can be broken down into the constituent molecules by the addition of H2O. as water is attracted to polar regions of the polymer, the links can be broken down
Features of condensation polymers and their uses
H bonding and dipoles form between separate polymer chains, holding them together in a strong structure, useful for bulletproof vests/ heat protective materials
Why are polyalkenes (addition polymers) difficult to dispose of
are inert with non-polar bonds, so species in nature can’t break them down. They are not biodegradable and broken down by burning which produces SO2/CO, leading to acid rain
How are polyesters broken down
- hydrolysis so are biodegradable
- with HCL - form og dicarboxylic acid + diol
- with NaOH - form diol + dicarboylate salt
How are polyamides broken down
hydrolysis so are biodegradable
- with HCL - form og dicarboxylic acid + diamine
- with NaOH - form diamine + dicarboylate salt
how can polyalkenes be broken down
They are chemically inert and non-biodegradable, so they have no polar bonds. broken down by burning releasing SO2 or CO
disposal of polymers
landfill
- common
- most are reaching capacity
- takes years to break down
disposal of polymers
incineration
- rubbish burn -> energy produced to generate electricity
- toxins and pollutants can be removed
- emitts greenhouse gases
- volume of rubbish reduced
dispsal of polymers
recycling
- saves raw materials
- polymers need sorting - expensive in terms of energy + manpower
- polymers can only be recycled into the same type, so careful separation is needed
- thermoplastic polymers can be melted and reshaped
