POLY(ETHYLENE OXIDE)-COATED GRANULAR STARCH-POLY (HYDROXYBUTYRATE-CO-HYDROXYVALERATE) COMPOSITE-MATERIALS

Granular cornstarch was coated with several biodegradable polymers in an effort to improve the mechanical properties of tarch-poly(3-hydroxy butyrate-co-3-hydroxyvalerate) (PHBV) composites. Only samples contain ing poly(ethylene oxide) (PEO)-coated granular starch showed a large i mprovement in tensile properties over uncoated starch. For example, a 50/50 blend of PEO-coated starch and PHBV had a tensile strength of 19 MPa and an ultimate elongation of 23%, compared to 10 MPa and 11% for a similar blend containing uncoated starch. PEO may act as an adhesiv e between the starch and the PHBV and/or increase the toughness and re sistance to crack growth of PHBV around the starch granules.