| Date | May 2017 | Marks available | 2 | Reference code | 17M.3.sl.TZ2.3 |
| Level | SL | Paper | 3 | Time zone | TZ2 |
| Command term | Identify | 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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18M.3.sl.TZ1.3b.i:
State the name given to a material composed of two distinct solid phases.
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18M.3.sl.TZ1.3a:
Discuss, in terms of its structure, why an aluminium saucepan is impermeable to water.
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18M.3.sl.TZ2.3a:
ICP-OES/MS can be used to analyse alloys and composites. Distinguish between alloys and composites.
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17M.3.sl.TZ2.3a:
State the two distinct phases of a composite.
- 16N.3.sl.TZ0.3a: Magnesium oxide, MgO, and silicon carbide, SiC, are examples of ceramic materials. State the...
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18M.3.sl.TZ1.4e:
Suggest why there are so many different ways in which plastics can be classified. HDPE can, for example, be categorized thermoplastic, an addition polymer, having Resin Identification Code (RIC) 2, etc.
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19M.3.hl.TZ1.3a:
Identify the type of bonding in lithium hydride, using sections 8 and 29 of the data booklet.
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19M.3.sl.TZ1.3a(i):
Identify the type of bonding in lithium hydride, using sections 8 and 29 of the data booklet.
- 16N.3.sl.TZ0.3b: Predict the predominant type of bonding for a binary compound AB in which the...
- 17N.3.sl.TZ0.4b.ii: At present, composite fillings are more expensive than amalgam fillings. Suggest why a...
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17M.3.sl.TZ1.6a:
Determine the type of bond present in SbBr3, showing your method. Use sections 8 and 29 of the data booklet.
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19N.3.sl.TZ0.5b(i):
Determine the percentage of ionic bonding in alumina using sections 8 and 29 of the data booklet.
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18M.3.sl.TZ2.4c:
Civilizations are often characterized by the materials they use.
Suggest an advantage polymers have over materials from the iron age.
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17N.3.sl.TZ0.4a:
Outline the composition of an alloy and a composite.
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17M.3.sl.TZ1.6b:
Lanthanum has a similar electronegativity to group 2 metals. Explain, in terms of bonding and structure, why crystalline lanthanum bromide is brittle.
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19M.3.hl.TZ2.4d:
Outline how alloys conduct electricity and why they are often harder than pure metals.
Conduct electricity:
Harder than pure metals:
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19M.3.sl.TZ2.4d:
Outline how alloys conduct electricity and why they are often harder than pure metals.
Conduct electricity:
Harder than pure metals:
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20N.3.hl.TZ0.3a:
Outline the two distinct phases of this composite.
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18N.3.hl.TZ0.2a:
Outline why this type of classification is not entirely satisfactory by using magnesium diboride, MgB2, as an example. Refer to sections 8 and 29 of the data booklet.
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18N.3.sl.TZ0.2a:
Outline why this type of classification is not entirely satisfactory by using magnesium diboride, MgB2, as an example. Refer to sections 8 and 29 of the data booklet.
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20N.3.sl.TZ0.3a:
Outline the two distinct phases of this composite.
