Investigation of Nonlinear Material Behavior Using Simultaneous Measurements of Volume Recovery and Physical Aging
Carl R. Schultesiz, G B. McKenna
At temperatures below the glass transition, amorphous polymers evolve slowly toward thermodynamic equilibrium. Some experiments have suggested that different material properties equilibrate at different rates, but such comparisons are typically made using different samples in different instruments, leading to questions about the comparability between the materials or thermal histories. Using the NIST Torsional Dilatometer, simultaneous measurements of volume (a measure of the thermodynamic state) and mechanical response (using torsional stress-relaxation experiments) can be made on he same sample. Recent experiments in this laboratory with an epoxy indicate that the volume and mechanical behavior equilibrate at the same time. The epoxy has also exhibited significant chemical aging, as manifested by increasing relaxtion times, over the (3 year) course of the experiments.
chemical aging, normal force, physical aging, torsion, volume recovery
and McKenna, G.
Investigation of Nonlinear Material Behavior Using Simultaneous Measurements of Volume Recovery and Physical Aging, Society for Experimental Mechanics, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=851548
(Accessed June 10, 2023)