All of these effects are named after John Henry Poynting, an English physicist.
In solid mechanics, the Poynting effect is a finite strain theory effect observed when an elastic cube is sheared between two plates and stress is developed in the direction normal to the sheared faces, or when a cylinder is subjected to torsion and the axial length changes.
[6][7][8] In thermodynamics, the Poynting effect generally refers to the change in the fugacity of a liquid when a non-condensable gas is mixed with the vapor at saturated conditions.
Equivalently in terms of vapor pressure, if one assumes that the vapor and the non-condensable gas behave as ideal gases and an ideal mixture, it can be shown that:[9] where A common example is the production of the medicine Entonox, a high-pressure mixture of nitrous oxide and oxygen.
The ability to combine N2O and O2 at high pressure while remaining in the gaseous form is due to the Poynting effect.