Working on a sustained high altitude balloon with amateur radio tracker

[ssiems]

Looking for balloon or material to produce a balloon for flight at approximately 90,000 feet with Amateur radio aprs and 20m wspr tracking for endurance run to navigate around the earth as many time as possible before failure

 

[COLGeek]

Have you researched any sites like this one?

https://launchwithus.com/

There are also a multitude of college/university sites with high altitude balloon experiments pages that might help you decide the best course of action for your project.