Biodegradable is defined as being able to be broken down by other living organisms. Nylon2-nylon-6, Dextran and PHBV are biodegradable, whereas, Nylon - 6,6 is nonbiodegradable.
However, Dextran and PHBV, both are polyesters and Nylon-2-nylon-6 is a polyamide. Dextran is formed by the polymerization of many glucose molecules.