Entropix said:
Where this balloon will stop? I'm more interested in the exact altitude it reaches or if it will keep going further away into the outer space.
It will stop somewhere, and cannot rise above the thin atmosphere, into space.
The balloon will start to rise when it is partly filled.
As it continues to rise, the hydrogen will expand until the envelope is full. At that point the density of the balloon is fixed by the volume of the full envelope, the mass of hydrogen, and the weight of the envelope.
Your balloon will still continue to rise, but only until the density of the atmosphere is the same as the density of the full balloon.
A weather balloon is designed to burst and fall back down before that point, but your balloon is made from stronger stuff.
It will become stable, floating at that level, while the hydrogen lifting gas gradually leaks from the envelope that is still under pressure, and it creeps up very slowly as the mass of hydrogen is reduced by envelope leakage, the density becomes lower, and it rises slightly, following the atmosphere with neutral buoyancy.
That is the highest it will get.
There will come a time, when the envelope is no longer tight. The balloon will begin to sink as its volume gradually falls, as it follows down the atmospheric hydrostatic density profile. This will take a long time as the envelope membrane is not under internal pressure, so hydrogen escapes at a lower rate.
Once it falls to about 50,000 feet, it will become a hazard to aircraft navigation, and you will wish it had burst earlier.
In the end it will be blown into a mountain, or fall into the sea.