Polyethersulfone

PES, acronym for polyethersulfone, was a petroleum-based plastic. Its appeareance was "slightly amber, almost opaque". It was produced at least on the planet Lakertya. Contrarily to PHB, it was not biodegradable.

The Rani employed it as a heat conducting material in the assembly of a Time Manipulator. (TV: Time and the Rani)