14A-26

J. T. KIM¹, D. S. CHA, and H. J. PARK. (1) Graduate School of Biotechnology, Korea University, 5Ka Anam-Dong, Sungbuk-Ku, Seoul, 136-701, South Korea

Justification: The sweet potato starch (SPS) is the major source in preparing Tangmyon (starch noodle) which is popular food in Korea, China and Japan. Solid waste from SPS plant has produced 30,000 M/T within 45 days only and needs to be paid US $830,000 by treatment cost per year in Cheju island, Korea. In view of the current emphasis on environmental pollution problems and in conjunction with the land shortage problems for solid waste management and pending legislation, growing concerns mentioned above has prompted studies into development of biodegradable plastics from byproduct in SPS plant. We have tried to develop sweet potato pulp (SPP)/cationic starch (CS) blended biodegradable plastics using by compression molding machine. Objective: Our objective was a) to produce biodegradable plastic from SPP/CS composites and b) to measure the mechanical properties of the plastics for industrial uses. Method: SPP mixture with 10% by weight of CS (degree of substitution (DS), 0.04, 0.08, 0.20) was compression molded. Instron, Rockwell hardness tester and Izod-type impact machine were used to evaluate mechanical properties of the plastics according to ASTM standard methods. A central composite second-order design based on response surface methodology was used to study the effects of moisture content, process temperature and running time on mechanical properties of the composite of SPP/CS. Result: The results indicate that the mechanical properties of the composite were strongly dependent on more moisture content than process temperature and running time. The higher DS of CS content had an adverse effect on the mechanical properties of SPP/CS blends plastics. For an example, the impact resistance properties of the plastics, which contained CS with DS 0.04 and 0.08 were higher than those of plastics contained CS with 0.20. Regression analysis predicted higher value of flexural and hardness properties to be attained with 150°É, 20min. and 20% moisture content. Significance: The intention of this study was preparation of biodegradable plastics from byproducts in potato starch processing plant and was the preset for the commercial biodegradable plastics from other biopolymers.