Baybond PU 330 Polyester urethane polymer Bayer MaterialScience Polyurethane (PU) - Polyurethane dispersions (PUDs) >> Polyester Anionic/non-ionic polyester urethane polymer. It is used as the film-forming component in glass fiber sizes. Baybond PU 330 is particularly well suited for the sizing of glass fibers used for the manufacture of thermosets. It has good film-forming properties and adhesion. Baybond PU 330 remains stable when exposed to shear forces. Polyester urethane polymer. Possesses good film-forming properties and adhesion.