Consider a heat shrink film (as used in shrink sleeves that decorate plastic or glass bottles). These materials are produced by blow extrusion. When the film is heated (hot steam, hot air or radiation) the film will retract to a smaller size, typically anisotropic (shrink more in one direction than in the other).
Empirical data is available for unconstrained samples of film. However in real life situations there are constraints to the movement of the film and the system will look for a balance of thermal shrink and elastric stretch forces.
What would be a practical model for the macroscopic mechanics of such film? This model should provide internal forces (shrink and stress forces) for a given temperature, strain and history of an small area of film.
I wonder how related this is to visco-elasticity? VE can be modeled as a system of springs and dampers. Because of the damper(s) the forces also depends on the history. Does it make sense to model heat shrinking as visco-elasticity with temperature-dependent springs and dampers?