There is an analogy for electron movements forward and backward in a conductor: the Newton's Cradle, or Newton Pendulum. The balls (electrons) do not travel. They just transmit the energy. Here a link of many:
Thermal diffusivity is the relationship among three properties: thermal conductivity, density and specific heat. In a conductive transient heat transfer process it determines how fast the Temperatur change inside the body.
The meaning can easily be explained with an analogie. Cooling a body is...
I came across with this forum looking up for thermal difusividad of polymer. I did some research about this topic in my doctoral thesis and I am still interested on this field