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.