Mohammad Kazem Maniei - Department of Chemical engineering, Isfahan University of Technology, Isfahan, Iran.
Rouhollah Bagheri - Department of Chemical engineering, Isfahan University of Technology, Isfahan, Iran.
Nasrin Etesami - Department of Chemical engineering, Isfahan University of Technology, Isfahan, Iran.

Modification of starch is increasingly being studied and modified starch is used for applications in synthetic polymers (Wurzburg, 1987; Whistler, 1984; Willett, 1994; George,Sullivan & Park, 1994; Kim, Chin, Yoon, Lee, Kim & Jung, 1998). The essential force for this activity is due to bothbiodegradability and a renewability resource of starch. Inmany studies starch and its derivatives are used as biodegradable fillers for different synthetic polymers. For thispurpose, graft polymerization of thermoplastic polymers onto starch is a best method for preparing composites of starch withsynthetic polymers (Wurzburg, 1987; Whistler, 1984) [1-2]. The objective of this study is to synthesis PS-g-starch copolymer by grafting of styrene on corn starch using benzoylperoxide as the initiator in an internal mixer, and obtaining to optimum grafting. The PS-g-starch copolymer derived fromthis study will be used as a processable thermoplastic (bio plastic) and also as a compatibilizer for PS/starch blends.