Novel bioabsorbable polyphosphate/soy protein plastic composites

Otaigbe, Joshua U.; Adams, Daniel O.

Department of Materials Science and Engingeering

Department of Aerospace Engineering and Engineering Mechanics

Iowa State University

Ames, IA USA

Abstract

This research focused on the development of bioabsorbable polyphosphate filler/soy protein plastic composites with enhanced stiffness, strength,and water resistance. Bioabsorbable polyphosphate fillers, biodegradable soy protein isolate, plasticizer, and adhesion promoter were homogenized and compression-molded. Phys., mech., and water absorption testing was performed on the molded specimens. Results showed improvements in stiffness, strength, and water resistance with increasing polyphosphate filler content up to 20 percent by wt. Application of a coupling agent produced further mech. property enhancements and a dramatic improvement in water resistance, interpreted by an interfacial chem. bonding model. Examn. of the fracture surfaces of the materials revealed that addn. of the polyphosphate fillers changed the failure mode from brittle to pseudo-ductile. These results suggest that these materials are suitable for many load-bearing applications in both wet and dry environments where current soy protein plastics are not usable.