Chemistry – Organic chemistry - Polymers | e-Consult

The student's statement is partially valid. It's true that the ester bonds in the PET polymer are susceptible to breaking, which is the basis for the depolymerisation process. However, the statement is incomplete because it doesn't mention the specific conditions required for these reactions.

Breakdown (Depolymerisation): The ester bonds in PET are broken by hydrolysis, which requires high temperatures (typically 200-250°C) and the presence of a catalyst (e.g., a metal salt). The high temperature provides the energy to overcome the strong covalent bonds in the polymer, and the catalyst speeds up the reaction. Water is also essential for the hydrolysis reaction to occur.

Re-polymerisation: The monomers (TPA and EG) then combine to form new PET through a condensation reaction. This reaction also requires high temperatures (around 280-300°C) and the removal of water as a byproduct to drive the equilibrium towards polymer formation. A catalyst is also typically used to facilitate the reaction.

Therefore, while the ester bonds are indeed breakable, the process requires specific conditions – high temperature, catalysts, and the presence/removal of water – to facilitate both depolymerisation and re-polymerisation. The student's statement omits these crucial details.