We use molecular-dynamics computer simulations to explore the influence of thermal and mechanical history of typical glassy polymers, atactic polystyrene (PS) and (bis)phenol A polycarbonate (PC), on their deformation. Polymer stress-strain and energy-strain developments have been followed for different deformation velocities, also in closed extension-recompression loops. The latter simulate for the first time the experimentally observed mechanical rejuvenation and overaging of polymers. Energy partitioning reveals essential differences between mechanical and thermal rejuvenation. All results are qualitatively interpreted by considering the ratio's of relevant timescales: for cooling down, for deformation, and for intrinsic segmental relaxation.
|Title of host publication||Proceedings of the XVth International Congress on Rheology : the Society of Rheology 80th annual meeting (ICR 2008), 3–8 August 2008, Monterey (California)|
|Editors||A. Co, G.L. Leal, R.H. Colby, A.j. Giacomin|
|Place of Publication||Melville, NY|
|Publisher||American Institute of Physics|
|Publication status||Published - 2008|
|Name||AIP Conference Proceedings|