| Date | May 2017 | Marks available | 3 | Reference code | 17M.3.sl.TZ2.3 |
| Level | SL | Paper | 3 | Time zone | TZ2 |
| Command term | Explain | Question number | 3 | Adapted from | N/A |
Question
Polymer nanocomposites often have better structural performance than conventional materials. Lithographic etching and metal coordination are two methods of assembling these nanocomposites.
Nanoparticles anchor plasticizers in PVC so that they cannot escape from the polymer as easily.
State the two distinct phases of a composite.
Identify the methods of assembling nanocomposites by completing the table.
Explain how the structure of plasticizers enables them to soften PVC.
Suggest a reason why nanoparticles can better anchor plasticizers in the polymer.
Markscheme
reinforcing «phase»
«embedded in» matrix «phase»
[2 marks]
Award [2] for all 4, [1] for 2 or 3 correct.
[2 marks]
Any three of:
contain a polar group «which locks into the polymer»
a non-polar group «which weakens the forces between chains»
embedded between chains of polymers
«plasticizer molecules» fit between chains
«plasticizer molecules» prevent chains from forming crystalline regions
«plasticizer molecules» keeps strands/chains/molecules separated
«plasticizer molecules» increase space/volume between chains
weakens intermolecular/dipole-dipole/London/dispersion/instantaneous induced dipole-induced dipole/van der Waals/vdW forces
Do not accept “«plasticizer molecules» “lower density” or “softer”.
[3 marks]
more places «for plasticizers» to bond
OR
increased surface area
[1 mark]
Examiners report
Syllabus sections
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17M.3.hl.TZ2.3c:
Estimate the atom economy of this first step.
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17M.3.sl.TZ1.10b.ii:
Explain why the difference in their structures affects their melting points.
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19M.3.sl.TZ2.5d:
Explain how plasticizers affect the properties of plastics.
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18M.3.sl.TZ1.4a:
Both of these are thermoplastic polymers. Outline what this term means.
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19M.3.hl.TZ2.5a:
Draw a section of isotactic polychloroethene (polyvinylchloride, PVC) showing all the atoms and all the bonds of four monomer units.
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19M.3.sl.TZ2.5a:
Draw a section of isotactic polychloroethene (polyvinylchloride, PVC) showing all the atoms and all the bonds of four monomer units.
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19M.3.hl.TZ1.4b:
Suggest, giving a reason, how elastomers used for the tyre tread can increase the traction between the tyre and the road.
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17M.3.sl.TZ1.10a:
Below are the IR spectra of two plastics (A and B); one is PETE, the other is low density polyethene (LDPE).
Deduce, giving your reasons, the identity and resin identification code (RIC) of A and B using sections 26 and 30 of the data booklet.
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16N.3.sl.TZ0.6a:
(i) Draw the structure of 2-methylpropene.
(ii) Deduce the repeating unit of poly(2-methylpropene).
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16N.3.sl.TZ0.6b:
Deduce the percentage atom economy for polymerization of 2-methylpropene.
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17M.3.sl.TZ2.3c.ii:
Suggest a reason why nanoparticles can better anchor plasticizers in the polymer.
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17N.3.sl.TZ0.7b.i:
Describe how the structures of LDPE and HDPE affect one mechanical property of the plastics.
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18M.3.hl.TZ1.4c.ii:
Deduce, giving a reason, whether the atom economy of a condensation polymerization, such as this, would be greater or less than an addition polymerization, such as the formation of HDPE.
- 19N.3.hl.TZ0.5b: State and explain why plasticizers are added to polymers.
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18N.3.sl.TZ0.2b.i:
Structures of poly(methyl acrylate), PMA, and Bakelite® are shown.
Suggest, giving reasons, which is the thermoplastic polymer and which is the thermosetting polymer.
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19N.3.sl.TZ0.4a:
Draw a section of an isotactic polypropene polymer chain containing four repeating units.
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18M.3.sl.TZ1.4b.ii:
State one way in which a physical property of HDPE, other than density, differs from that of LDPE as a result of this structural difference.
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18M.3.sl.TZ2.4a:
Sketch four repeating units of the polymer to show atactic and isotactic polypropene.
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17M.3.sl.TZ1.10b.i:
Describe the difference in their structures.
- 19N.3.sl.TZ0.4b: Predict, with a reason, whether isotactic or atactic polypropene has the higher melting point.
- 19N.3.sl.TZ0.4c: Polypropene is a thermoplastic. Outline what is meant by thermoplastic.
- 19N.3.sl.TZ0.4d: Discuss why the recycling of plastics is an energy intensive process.
- 20N.3.sl.TZ0.3b(i): Thermoplastic composites are increasingly replacing thermosets. Suggest one advantage of...
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19M.3.hl.TZ2.5c:
Explain how plasticizers affect the properties of plastics.
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16N.3.sl.TZ0.6c:
(i) Suggest why incomplete combustion of plastic, such as polyvinyl chloride, is common in industrial and house fires.
(ii) Phthalate plasticizers such as DEHP, shown below, are frequently used in polyvinyl chloride.
With reference to bonding, suggest a reason why many adults have measurable levels of phthalates in their bodies.
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19M.3.sl.TZ1.4b:
Suggest, giving a reason, how elastomers used for the tyre tread can increase the traction between the tyre and the road.
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18N.3.hl.TZ0.2b:
Structures of poly(methyl acrylate), PMA, and Bakelite® are shown.
Suggest, giving reasons, which is the thermoplastic polymer and which is the thermosetting polymer.
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18M.3.sl.TZ1.4b.i:
Compare and contrast the structures of HDPE and LDPE.
- 20N.3.sl.TZ0.3c: Explain why phthalates are replaced by other plasticizers in the production of plastics.
- 20N.3.hl.TZ0.3b(iii): Explain why phthalates are replaced by other plasticizers in the production of plastics.
- 20N.3.hl.TZ0.3b(i): Thermoplastic composites are increasingly replacing thermosets. Suggest one advantage of...
- 20N.3.hl.TZ0.3b(ii): Explain how thermoplastics, such as polyvinylchloride, PVC, can be made more flexible by the...
- 20N.3.sl.TZ0.3b(ii): Explain how thermoplastics, such as polyvinylchloride, PVC, can be made more flexible by the...
