Draw a short length of the PLA polymer chain with at least two monomer residues included. The methyl groups may be written as $-\text{CH}_3$, but all the other bonds should be shown in full display. Label one repeat unit of polylactic acid on your diagram.
State the type of polymerisation involved in producing PLA and the functional group formed between the monomers. type of polymerisation .............................................................. functional group ..............................................................
Predict whether PLA is readily biodegradable. Explain your answer.
Use Fig. 8.1 together with Table 8.1 to complete Table 8.2.
Name the substance that gives the peak at $\delta = 0.0$.
Explain why $\text{CDCl}_3$ is a more suitable solvent than $\text{CHCl}_3$ for proton NMR.
Explain what retention time means.
Suggest suitable substances, or types of substances, that could be used for the mobile and stationary phases. mobile phase .............................................................. stationary phase ..............................................................
Describe how the percentage composition of the mixture can be worked out from the gas/liquid chromatogram.