Meaning
Materials scientists measure the rate of polymer yield under varying shear stresses to determine the size of the molecular segment involved in plastic deformation. The eyring activation volume represents this physical scale, defining the localized volume required for polymer chain segments to move past each other under load. It governs the transition from elastic behavior to plastic flow under high-stress conditions.
This metric outlines the boundary where a polymer shifts from solid-like response to liquid-like flow.
Molecular Mobility
High shear stress lowers the energy barrier for molecular movement, which is modeled as a stress-activated process. Calculating the eyring activation volume requires running tensile or compression tests at different strain rates and temperatures. If the volume is large, it means a substantial portion of the chain must rearrange for flow to occur.
This indicates that the material resists yielding except under high loads.
Yield Stress
The yield behavior of glassy polymers is highly sensitive to the activation volume. A smaller eyring activation volume leads to a more localized response to applied loads. It accelerates the onset of yield at low stresses.
Polymer Mechanics
Component design must account for how this parameter changes during long-term storage or aging. As a material ages, the packing of the polymer chains becomes tighter, which restricts molecular motion. This densification reduces the apparent eyring activation volume and increases the brittleness of the fabricated part.
This change can result in unexpected failures.
