IntermediateTopic 42 of 100Materials & Chemical
Elastomers
Rubber-like polymers with large reversible strains.
In depth
Elastomers have lightly cross-linked, coiled chains giving large reversible strains (>500%) and low modulus: natural rubber, SBR, nitrile, EPDM, silicone, polyurethane. Vulcanisation with sulphur crosslinks natural rubber. Fillers (carbon black) raise strength; used in tyres, seals, mounts.
Key points
- Entropy elasticity
- Hysteresis and damping
- Compression set
ExampleO-rings seal hydraulic systems using nitrile or Viton rubber.
Elastomers stretch a lot and return to shape, which is why they are used for seals, tyres, mounts and gaskets.
What is Elastomers?
Rubber-like polymers with large reversible strains.
Why is it important to understand elastomers?
Elastomers stretch a lot and return to shape, which is why they are used for seals, tyres, mounts and gaskets.
Why are rubbers elastic?
Cross-linked polymer chains want to coil, so stretching reduces entropy and the material pulls back when released.
What limits elastomer use?
Temperature, ozone, oil and ageing can harden or degrade rubber, so material selection must match the service conditions.
How is Elastomers used in practice?
Typical applications include making an O-ring to seal a hydraulic cylinder, choosing a rubber mount to isolate vibration from an engine and designing a seal that must retain its elasticity over a wide temperature range.
What should I learn before Elastomers?
Study "Thermosets" first (topic 41 of 100 in Materials & Chemical). It covers the groundwork this topic builds on.
What are the key points of Elastomers?
Entropy elasticity. Hysteresis and damping. Compression set.
Can you give an example of Elastomers?
O-rings seal hydraulic systems using nitrile or Viton rubber.
What comes after Elastomers?
The next topic is "Viscoelasticity", which builds directly on this one.
How difficult is Elastomers?
It is classed as Intermediate in Materials & Chemical (topic 42 of 100). It is an intermediate topic. Work through the beginner topics in Materials & Chemical first.