Quote by Red_CCF
Hi, thanks for the response
For instance, I imagine that there is more than one polytropic (or any) process from two equilibrium states for which work can be applied, but from Tds = de + pdv, the integral of the p/Tdv term (taking T constant) would result in different values while e2e1 doesn't change if the initial and final states are the same.

True, but take in mind that to obtain Delta S you have to integrate de/T, not de. Both p and T will be different in different polytropic processes.