Shape-memory Polymers Vs. Shape-memory Alloys
| SMPs | SMAs | |
|---|---|---|
| Density (g/cm3) | 0.9–1.2 | 6–8 |
| Extent of deformation |
up to 800% | <8% |
| Required stress for deformation (MPa) |
1–3 | 50–200 |
| Stress generated upon recovery (MPa) |
1–3 | 150–300 |
| Transition temperatures (°C) |
−10..100 | −10..100 |
| Recovery speed | 1s – minutes |
<1s |
| Processing conditions |
<200 °C low pressure |
>1000 °C high pressure |
| Costs | <$10/lb | ~$250/lb |
Shape-memory polymers differ from shape memory alloys by their glass transition or melting transition from a hard to a soft phase which is responsible for the shape-memory effect. In shape-memory alloys martensitic/austenitic transitions are responsible for the shape-memory effect. There are numerous advantages that make SMPs more attractive than shape memory alloys. They have a high capacity for elastic deformation (up to 200% in most cases), much lower cost, lower density, a broad range of application temperatures which can be tailored, easy processing, and potential biocompatibility and biodegradability.
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