ARS | Publication request: BIODEGRADABLE COMPOSITES OF STARCH AND POLY(HYDROXYBUTYRATE-CO-VALERATE) COPOLYMERS

Submitted to: Satake Centre for Grain Process Engineering
Publication Type: Abstract Only
Publication Acceptance Date: June 6, 1996
Publication Date: N/A

Technical Abstract: Poly(hydroxybutyrate-co-valerate)(PHBV) copolymers are biodegradable alternatives to nonbiodegradable resins currently used in disposable applications. Market penetration has been limited due to the high cost of these polymers relative to the commodity thermoplastics currently in use. Under a Cooperative Research and Development Agreement (CRADA) between the USDA's Agricultural Service and Zeneca Bioproducts, the use of starch as a low cost, biodegradable filler in composites with Biopol PHBV resins has been investigated. Using statistical experimental design, predictive equations for the effects of formulation variables on properties have been developed for composites containing PHBV, starch, plasticizer, and inorganic filler. These equations can be used to maximize the starch content of a composite consistent with the end-use performance requirements of the material for both rigid and flexible formulations. Mechanical properties are improved when the starch is coated with a thin layer of adsorbed polyethylene oxide (PEO). The PEO reduces the rate of biodegradation when composites are exposed to activated municipal sewage sludge. Starch modified with various levels of surface grafted glycidyl methacrylate gave improved mechanical properties relative to untreated starch. The effects of formulation variables on degradation rate have been examined for samples buried in soil. (Research was conducted under CRADA 58-3K95-M-013.)