The structure of a quenched sample of a liquid crystalline polyester, poly(diethylene glycol-p,p'-bibenzoate) (PDEB), and its physical aging was studied by microhardness methods (MH), wide-angle X-ray scattering (WAXS), and positron annihilation lifetime spectroscopy (PALS). It was established that the smectic layers in the liquid crystalline domain are oriented parallel to the sample plane. Physical aging leads to an increase of either the Vickers microhardness, directly related to the elastic modulus of the material, or the total microhardness, which includes all the components of the overall deformation. These mechanical changes are due to a decrease in the sizes of nanopores and the consequential increase of the density of the disordered phase.