This question is about addition polymerisation and the physical properties of polymer materials.
Phenylethene (styrene, C6H5CH=CH2\text{C}_6\text{H}_5\text{CH}=\text{CH}_2C6H5CH=CH2) undergoes addition polymerisation to produce poly(phenylethene). The equation below shows this reaction:
Identify the chemical group represented by the letter A A\,A and the symbol represented by the letter BBB.
Poly(phenylethene) is classified as a thermosoftening polymer. Contrast the structural features of thermosoftening polymers like poly(phenylethene) with thermosetting polymers, and explain how this structural difference affects their response to heating.
Rigid plastic items like water bottles are often made from high-density poly(ethene) (HDPE), whereas flexible plastic squeeze bottles are made from low-density poly(ethene) (LDPE). Explain, in terms of their structures and intermolecular forces, why HDPE has a significantly higher density and melting point than LDPE.