Saeed Rahimi - rubber, Iran polymer & petrochemical institute, Tehran, Iran.
Mohammad Karabi - rubber, Iran polymer & petrochemical institute, Tehran, Iran.
Ismaeil Ghasemi - rubber, Iran polymer & petrochemical institute, Tehran, Iran.
Hamed Azizi - rubber, Iran polymer & petrochemical institute, Tehran, Iran.

Starch, as a natural polymer, has attracted considerable interest due to its abundantly available, Renewability, Biodegradability and of relatively low cost [1]. However, insome cases chemical modification of starch is required to reduce hydrophobicity and to improve mechanical and moisture barrier properties [1-2]. Recently Andrade et al. [2] modified the thermoplastic starch in the presence of maleic anhydride and benzoyl peroxide asinitiator in the solid state. They reached out to very low degree of substitution (DS) due to using of the low temperature (50ºc). In this study, the chemical modification of thermoplasticstarch (TPS) was carried out in the presence of maleicanhydride (MA) as a modifier and glycerol as a plasticizer in melt state. The process was performed in the high temperature for the relatively long resides time with using an internal mixer. In order to, maleated thermoplastic starch (MTPS)having enhanced reactivity and reduced melt-viscosity. The grafting of MA to the thermoplastic starch was evaluated byFourier transform infrared spectroscopy after soxhlet extraction with acetone. Furthermore, the degree of substitution for MTPS was measured by alkaline titration for the carboxyl group