Mechanical Engineering, Mechanics of Materials
We present a new molecular-level picture of chain dynamics for describing the viscoelasticity of crosslinked polymers. The associated mathematical model consists of a time-dependent momentum balance on a representative polymer segment in the crosslinked network, plus phenomenological expressions for forces acting on the segments. These include a cohesive force that accounts for intermolecular attraction, an entropic force describing the thermodynamics governing chain conformations, and a frictional force that captures the temperature dependence of relative chain motion. We treat the case of oscillatory uniaxial deformation. Solution of the model equations in the frequency domain yields the dynamic moduli as functions of temperature and frequency. The model reproduces all of the qualitative features of experimental dynamic modulus data across the complete spectrum of time and temperature, spanning the glassy zone, the β transition, the dynamicglass transition, and the rubbery zone. All of the model parameters can be evaluated through the use of independent experimental data. Comparison of model predictions with experimental data yields good quantitative agreement outside of the glass transition region.
Published in Journal of Rheology, Volume 41, Issue 3, 1997, pages 641-670.
© Journal of Rheology 1997, American Institute of Physics
Simon, P. P. & Ploehn, H. J. (1997). Molecular-level modeling of the viscoelasticity of crosslinked polymers: effect of time and temperature. Journal of Rheology, 41(3), 641-670.