Submitted to: Starch Convention
Publication Type: Abstract Only
Publication Acceptance Date: April 24, 1998
Publication Date: N/A
Technical Abstract: Granular starch is an attractive filler for use in biodegradable materials due to its low cost and rapid biodegradability. In general, the particle size of commercially available starches is too large to offer reinforcement of mechanical properties such as stiffness or strength. From a materials science viewpoint, granular starch behaves analogously to other spherical fillers in polymer matrices: the influence of filler content on properties is dependent on particle size and adhesion at the particle-matrix interface. Most biodegradable polymers of interest exhibit poor adhesion to starch, with the result that starch content is generally limited to relatively low values due to unacceptable loss in properties. We have investigated various approaches to improving the adhesion between starch and biodegradable polyesters such as PHBV, including the use of statistical design in formulation, coating the starch granules with another polymer, and grafting reactive polymers onto the starch granules. These approaches yield improved properties and higher starch contents. In these systems, failure is dominated by debonding at the matrix-granule interface. In composites where the adhesion is great enough, the failure mechanism is dominated by the properties of the starch granules.