Question
Sections of two forms of polystyrene are shown:
(a) (i) Draw the structural formula of the monomer from which they were formed.
(ii) Identify, giving one reason, the form with the higher melting point.
(b) Explain how a substance in the same phase as the reactants can reduce the activation energy and act as a catalyst.
(c) Solutions of substituted polystyrenes can form lyotropic liquid crystals. Outline how lyotropic liquid crystals differ from other liquid crystals.
(d) Expanded polystyrene (EPS) is a useful material.
(i) Explain how polystyrene is converted to EPS.
(ii) State one property of EPS that makes it a useful material.
Nylon-6 is a polymer that can be formed from the monomer:
(e) State the type of polymerization reaction that occurs and the structural characteristic of the monomer that allows this type of polymerization to occur.
Type of polymerization:
Structural characteristic:
(f) Outline why plastics do not break down easily in the environment.
(g) State the RIC number for polyamide plastic (nylon). Use section 30 of the data booklet.
Answer/Explanation
Answer:
(a) (i) 
(ii) B AND chains «of polymer» can align/pack more closely
(b) forms an intermediate/activated complex
«intermediate/activated complex» dissociates to form product «AND catalyst»
(c) «lyotropic liquid crystals» exist over a given concentration range AND other liquid
crystals exist over a certain temperature range
(d) (i) volatile hydrocarbon/pentane «incorporated in beads of the polymer»
vaporizes/boils when heated «causing polymer to expand»
(ii) «good» thermal/electrical insulator
OR
soft/provides shock resistance
OR
low density
OR
easily moulded/versatile
OR
water resistant
OR
durable
(e) Type of polymerization: condensation
Structural characteristic: two functional groups
(f) strong covalent bonds
(g) «RIC» 7
Question
$\operatorname{Kevlar}^{\circledR} \text { is used to make racing tires. }$
a. Draw the structure of the monomers of Kevlar ${ }^{\circledR}$ if the by-product of the condensation polymerization is hydrogen chloride.
b. State and explain why plasticizers are added to polymers.
c. Discuss why the recycling of plastics is an energy intensive process.
▶️Answer/Explanation
Markscheme
a.
b. increases flexibility/softness/plasticity
break/weaken intermolecular forces/IMF/H-bonds «between chains»
c. Any two of:
collection/transportation of plastic waste
separation/sorting of different types «of plastic»
OR
separation/sorting of plastic from other materials
melting plastic
processing/washing/cleaning/drying/manufacture of recycled plastic