I've come across this term a few times. IIRC, liquid hydrogen is "self-pressurizing", but other fuels are not. Apparently, if a propellant is self-pressurizing, we do not need to build any complex plumbing to repressurize the tank as the propellant is used up.
I understand that, normally, a tank would undergo adiabatic cooling as its pressure drops (as propellant is used up by the engine), and thus the tank would eventually crack from the extreme temeperature differential. So it's important to keep the tank pressurized even as fuel is depleted. What I don't understand is how a certain propellant can be "self-pressurizing" even tho we are using up that propellant.
What fuels and oxidizers are self-pressuring, and what ones aren't? And why and how?
P.S. Chemistry and math are fine in your answer. I'm not afraid of either.