Polymer glasses are rheologically complex materials whose viscoelastic response is a function of the kinetics of structural relaxation. To circumvent the complexity, several experimental loading protocols have been established over the years, but the results have not led to a unifying concept. From a theoretical point of view, we tackled the problem by coupling the structural relaxation kinetics with the constitutive equation for linear viscoelasticity written in the reduced time domain. In this article, we substantiate the reliability of our approach. Geometrical descriptions and thermodynamic rules motivated a constitutive coupling of viscoelastic and structural relaxation phenomena, and that represents the novelty in our theory. The axial creep response is simulated following the thermal/mechanical loading sequence known as Struik's Protocol. Simulation is extended to a vanishing stress, and we showed that the time-aging time superposition procedure holds true above a given stress threshold. Furthermore, we extend our study to a single-step stress relaxation experiments to predict the glass densification that occurs in uniaxial tension (known as "volume implosion") and compression. (C) 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 724-739, 2009