* For a polymer to exhibit the thermally induced shape-memory effect, it must have anchor points for temporary and permanent shape. These can be physical (chain entanglements, crystals) or chemical (chemical crosslinking, curing, vulcanization).
* This effect in polymers depends on entropic forces and not on martensitic transitions like metals.
* The most important physical properties are: elastic modulus, recovery speed, temporary shape stability.
* The transition temperature T can be Tm or Tg or a mixture of both.
* All crystalline polymers (except for PP) can exhibit thermally induced shape-memory effect.
* Inelastic mechanisms that decrease the effect are: moisture degradation (for moisture sensitive polymers e.g. polyurethanes), unraveling of the chains, degradation of the bonds that fix the permanent or temporary shape.