13012 12 Benzene-1,4-dicarboxylic acid may be used to synthesise polyamide and polyester polymers. COOH COOH benzene-1,4-dicarboxylic acid (a) (i) Name the polyester formed from benzene-1,4-dicarboxylic acid and ethane-1,2-diol. [1] (ii) Draw one repeating unit of the polyester named in (a)(i). [1] 13012 [Turn over (b) The polyamide Kevlar is made from the reaction of 1,4-diaminobenzene with benzene-1,4-dicarboxylic acid. The melting point of Kevlar is over 500 °C. The diagram below shows two Kevlar polymer chains. O N H N H O O N H N H O N H N H O O N H N H O O (i) Suggest the type of bond represented by the dotted lines in the diagram above. [1] (ii) Explain, using the diagram above, why Kevlar has such a high melting point. [1] (c) Explain why polyamides and polyesters are biodegradable. [2]