* A commercial, high purity (non-recycled) polymer sample with known molecular mass distribution can be obtained or synthesized according to standard procedures.
* Common properties such as elastic modulus, tan δ, crystallinity, viscosity, density should be characterized.
* Anchor points, physical or chemical (chain entanglement, crystallinity or vulcanization), must be decided.
If crosslinking with slight vulcanization is desired, standardized methods for each polymer must be taken into account. In the case of PCO, for example, it is a polymer without shape-shape-memory effect because it does not present a clear "plateau", but the addition of a minimum amount of peroxide (~1%) provides PCO with all the requirements to present this effect.
# A permanent stress-free shape with known dimensions is prepared by conventional methods.
# The system is programmed, i.e. it is heated up to T and at that temperature the shape is modified by applying pressure or stress. Then the material is cooled and finally the pressure or stress is removed.
# After heating the sample again to T, the stresses are released and the permanent shape is recovered.
Some polymers fatigue first, so each system can be evaluated with a simple experiment that consists of programming the system 10 or 20 times in a row and measuring the recovery in % and time.