Polymers Flashcards
Addition
An addition polymer forms when unsaturated monomers react to form a polymer
Monomers contain C=C bonds
polyalkenes biodegradable
Poly(alkenes) are chemically inert due to the strong C-C and C-H bonds and non-polar nature of the bonds and therefore are non-biodegradable.
Condensation
polyesters and polyamides which involve the formation of an ester linkage or an amide linkage.
In condensation polymerisation there are two different monomers that add together and a small molecule is usually given off as a side-product e.g. H2O or HCl.
The monomers usually have the same functional group on both ends of the molecule e.g. di-amine, di carboxylic acid, diol, diacyl chloride.
Carboxylic Acid + Alcohol
Ester + water
Carboxylic Acid + Amine
amide + water
Acyl chloride + Alcohol
Ester + HCl
Acyl chloride + Amine
amide + HCl
dicarboxylic acid + diol
poly(ester) + water
dicarboxylic acid + diamine
poly(amide) + water
diacyl dichloride + diol
poly(ester) + HCl
diacyl dichloride + diamine
poly(amide) + HCl
Terylene
n O=C-⏣-C=O
HO- -OH
and ethan-1,2-diol
HO-CH2-CH2-OH
Nylon 6,6
hexanedioic acid + hexane-1,6-diamine
Hydrolysis
Polyesters and polyamides can be hydrolysed by acid and alkali
The hydrolysis will result in the original monomers forming- although the carboxylic acid or amine group will be in salt form depending on whether the conditions are alkaline or acidic
The reactivity can be explained by the presence of polar bonds which can attract attacking species such as nucleophiles and acids
Intermolecular bonding between condensation polymers chains
Polyesters have permanent dipole forces between the Cδ+=Oδ- groups in the different chains in addition to the van der waals forces between the chains.
Polyamides (and proteins) have hydrogen bonding between the oxygen in Cδ+=Oδ- groups and the H in the Nδ- —Hδ+ groups in the different chains in addition to the van der waals forces.
Polyamides will therefore have higher melting points than polyesters.
Landfill
The most common method of disposal of waste in UK
Many are now reaching capacity.
European regulations will mean councils are charged much more for using landfill.
Most polymers (polyalkenes) are non-biodegradable and take many years to break down.
Could use more biodegradable plastics, e.g. Polyamides and cellulose and starch based polymers to improve rates of decomposition
Incineration
Rubbish is burnt and energy produced is used to generate electricity.
Some toxins can be released on incineration. Modern incinerators can burn more efficiently and most toxins and pollutants can be removed. Greenhouse gases will still be emitted though.
Volume of rubbish is greatly reduced.
Recycling
Saves raw materials- nearly all polymers are formed from compounds sourced/produced from crude oil. Saves precious resources.
Polymers need collecting/ sorting- expensive process in terms of energy and manpower.
Polymers can only be recycled into the same type – so careful separation needs to be done.
Thermoplastic polymers can be melted down and reshaped
