PROCESSING AND MECHANICAL-PROPERTIES OF BIODEGRADABLE POLY(HYDROXYBUTYRATE-CO-VALERATE)-STARCH COMPOSITIONS

Poly(hydroxybutyrate-co-valerate) (PHBV) is a completely biodegradable thermoplastic polyester produced by microbial fermentation. The curre nt market price of PHBV is significantly higher than that of commodity plastics such as polyethylene and polystyrene. It is therefore desira ble to develop low-cost PHBV based materials to improve market opportu nities for PHBV. We have produced low-cost environmentally compatible materials by blending PHBV with granular starch and environmentally be nign CaCO3. Such materials can be used for specific applications where product biodegradability is a key factor and where certain mechanical properties can be compromised at the expense of lower cost. The inclu sion of granular starch (25 wt%) and CaCO3 (10 wt%) in a PHBV matrix ( 8% HV, 5% plasticizer) reduces the cost by approximately 40% and has a tensile strength of 16 MPa and flexural modulus of 2.0 Gpa, while the unfilled PHBV/plasticizer matrix has a tensile strength of 27 MPa and a flexural modulus of 1.6 GPa.