Polymer properties by design

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  • Created by: J.E.C.
  • Created on: 12-04-14 18:22
For a condensation polymer to be produced the monomer must have...?
At least two suitable functional groups per molecule.
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During condensation polymerisation, what two things are produced?
A longer chain polymer & a small stable molecule
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Nylons are ___ formed by reacting a ___ with a ___?
Polyamide, diamine, dicarboxylic acid
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What two things would you react to get nylon-6,6 ad what would be eliminated?
1,6-diaminohexane & hexane-1,6-dioic acid. Water eliminated.
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Describe the crystalline and amorphous regions of a substance in the glassy state?
Tangled polymer chains in the amorphous region are frozen so cannot move easily. If it needs to change shape it will simply break.
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What is meant by Glass Transition Temperature (Tg)?
Temperature at which polymer chains can move relative to each other.
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How does a polymer behave above it's Tg?
Becomes flexible and shows typical plastic properties.
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What happens when the melting temperature (Tm) is reached?
The crystalline areas break down and the polymer becomes a viscous fluid.
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The melting and glass transition processes are reversible for ___?
thermoplastics
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In general the longer the chain the stronger the polymer, however...?
A critical length has to be reached before the strength increases.
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What is meant by tensile strength?
A measure of how much you have to pull on a sample of a polymer before it snaps.
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How might having longer chains increase the tensile strength of a polymer?
Longer chains are more tangled, making it harder for them to slide over each other therefore reducing flexibility.
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How would having more points of contact along polymer chains, increase the tensile strength?
Longer chains have more points of contact with neighbouring polymer molecules. More IM bonds > chains attracted to each other more strongly > more difficult for chains to slide over each other = less flexible.
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To make a polymer more flexible, you need to lower...?
The Tg
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Describe copolymerisation and how this would decrease the Tg?
Introduce different side groups into the polymer chain, so chains pack together less well and bonds between them are weaker. So the polymer is more flexible and chains can move over each other more easily.
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What is the effect of a plasticiser?
Acts as a molecular lubricant by allowing chains to slide around each other more easily. Lowers Tg.
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How is a crystalline region arranged?
The areas in a polymer where the chains are closely packed in a regular way.
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How is an amorphous region arranged?
Chains are further apart and have more freedom of movement.
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Describe the process of cold-drawing?
When a polymer is stretched until all the polymer chains are aligned
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What is the effect of cold-drawing?
Proportion of crystalline regions is increased so polymer is stronger. Process used to produce tough fibres.
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Other cards in this set

Card 2

Front

During condensation polymerisation, what two things are produced?

Back

A longer chain polymer & a small stable molecule

Card 3

Front

Nylons are ___ formed by reacting a ___ with a ___?

Back

Preview of the front of card 3

Card 4

Front

What two things would you react to get nylon-6,6 ad what would be eliminated?

Back

Preview of the front of card 4

Card 5

Front

Describe the crystalline and amorphous regions of a substance in the glassy state?

Back

Preview of the front of card 5
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