Rubbery

What a bad restaurant! The beef was so rubbery I thought I'd never finish chewing it.

In this same temperature range, however, the leg is at its rubberiest.

If you boil it for hours, it becomes rubbery and overcooked.

CJ Biomaterials was the first company in the world to produce amorphous PHA, it says, which is a softer, rubberier version of PHA that offers fundamentally different performance characteristics than crystalline or semi-crystalline forms of the biopolymer.