https://www.dailymail.co.uk/sciencetech/article-10245623/Made-Chelsea-star-developing-rocket-engine-powered-plastic.html
Rocket engine powered by PLASTIC WASTE and developed by Made
in Chelsea star completes a successful test firing
. . .
Well, I'm sure it WORKS - Branson's tourist shuttle also
uses a sort of rubber/plastic compound and N2O for
power ... a "hybrid rocket". You can also use liquid
oxygen, but it's more a pain to deal with. Nitrous can
be liquified at pretty easy temperatures and pressures.
So can nitrogen tetroxide, but it's corrosive ; ozone
too, but it tends to go Bang (BEAUTIFUL blue color
though). Hmm, any trick to stabilize ozone ? That'd
be yer perfect oxidizer for a hybrid system.
But are melted plastic bags "better" ? I highly doubt it.
This was a gimmick demonstration.