High-performance lower-limb prosthetic sockets must be both durable and comfortable for the user. They are often manufactured with a soft, lightweight poly(ethene) inner liner surrounded by a highly rigid, carbon-fibre reinforced polyester composite outer shell.
The displayed structural formula of poly(ethene) is shown below:
[HH∣∣−C−C−∣∣HH]n \left[ \begin{array}{cc} \text{H} & \text{H} \\ | & | \\ -\text{C} & -\text{C}- \\ | & | \\ \text{H} & \text{H} \end{array} \right]_n H∣−C∣HH∣−C−∣HnAn incomplete displayed structural formula of the monomer ethene is shown below:
HH CC HH \begin{array}{cc} \text{H} & \text{H} \\ \ \ \text{C} & \text{C} \\ \ \ \text{H} & \text{H} \end{array} H C HHCHComplete the structural formula of the monomer ethene by describing the necessary bonds to connect all the atoms correctly.
The rigid outer shell of the prosthetic contains a polyester. Two monomers, X and Y, are reacted to make this polyester:
Name the functional group in monomer Y.
Monomers X and Y undergo condensation polymerisation to produce the polyester and a small molecule. Name this small molecule.
Explain, in terms of structure and bonding, why this polyester outer shell melts when it is heated.
The outer shell is a composite material containing carbon fibres embedded in a polyester resin matrix. Match each material to its correct role as either the matrix or the reinforcement:
Suggest two physical or mechanical reasons why this tough, rigid composite outer shell is added to the soft poly(ethene) inner liner.
5 exam-style questions on AQA GCSE Chemistry 7.3 Synthetic and naturally occurring polymers, covering 7.3.1 Addition polymerisation, 7.3.2 Condensation polymerisation (HT only), 7.3.3 Amino acids (HT only), and 7.3.4 DNA (deoxyribonucleic acid) and other naturally occurring polymers. Each one has a worked solution and a mark scheme showing where the marks go.