Biodegradable polyesters
2 marks · NormalDescribe how polylactic acid (PLA) is produced from its monomer, lactic acid.
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Lactic acid molecules react with each other in condensation polymerisation, losing water and forming ester linkages to create polylactic acid (PLA).
Also accept: PLA is formed when lactic acid molecules join together, losing water and forming ester bonds.
Common mistakes: Not specifying loss of water; Missing ester linkage
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Marking points
M1 · 1 mark · Refers to condensation polymerisation (or equivalent process).
A1 · 1 mark · States that water is eliminated and ester linkages are formed.
Worked solution
PLA is produced when lactic acid monomers undergo a condensation polymerisation reaction, each time losing a molecule of water and forming an ester bond to create a long-chain polymer.