The activation energy of a relaxation transition or of viscosity tells you something about the energy of internal movement and the formation of free volume. If the intermolecular forces are weak and if the molecular packaging is loose, you will have lower activation energy. In the case of polymers I have seen molecular mechanics estimations to select the proper mechanism, by comparing the calculated and measured activation energies.

Thank you Sir for giving a satisfactory answer. 

Good answer for Pr. Gyorgy Banhegyi.

Supplement idea: you can think about the ratio; Ea/(R*intercept of ordinate) from the straight line with which you are determined the Arrhenius parameters, you find an equivalent to temperature (TA), we have found in viscosity that this temperature is closely related to the boiling temperature (interesting for estimation or prediction). May be your Arrhenius temperature (TA) has an interesting original physical meaning!!!

Good idea and thanks for response to the questions