https://www.pddnet.com/news/2016/10...=5641964&et_rid=%%subscriberid%%&location=top In this case did the copper shrank or just the plastic , and made the copper frame bend ?
I note the article is careful to say it is the "structure" that shrank, not the materials themselves. It will be some process involving bending, for sure. What they have done, I think, is to design an ingenious structure in which the net effect of the bending is such as to reduce the overall dimensions of the the structure, which is far from solid. If one were to immerse this structure in a fluid of known coefficient of expansion and then heat it, my guess is one could measure the displacement of fluid and thereby the expansion of the materials comprising the structure.
So I can see the plastic material could be a compounded material and then as the temperature is rised the reactive material polymerise and so the volume decrease and bend the structure .?
When shrink wrap shrivels through heating, it is again the dimensions of the film (the structure) that shrink, not the volume of the material.
Well that is a change of state, a one-off change, occurring at a specific temperature, rather than a behaviour observed over a temperature range, as it seems to be here.
