“…Macroscopic deformation is assumed to be the result of a basic processes that is either intermolecular (i.e., chain‐sliding) or intramolecular (i.e., a change in the conformation of the chain) mobility, whose frequency depends on the ease with which a chain segment can surmount a potential energy barrier of height . So, in order to clarify the intrinsic physical mechanism for the strain rate dependency of the PMMA material in the different regions, Eyring's equation is employed, as below wherein, is the yield stress; is the test temperature in K ; is the activation energy of plastic deformation (plastic flow), i.e., the height of potential energy barrier of two adjacent equilibrium positions for element units to jump; is the activation volume of the element motion unit; is the strain rate; is the pre‐exponential factor, and is the gas constant.…”