Starch grafted poly(butylene succinate) via conjugating reaction and its role on enhancing the compatibility

•Starch-g-PBS can be accomplished by simply conjugating reaction.•PBS can graft on starch at both primary and secondary alcohol.•Starch-g-PBS showed good performance as a compatibilizer between PBS and starch.•Starch-g-PBS improved the mechanical properties of starch/PBS blend for 2 times. A single step process of grafting poly(butylene succinate) (PBS) on starch to obtain starch-g-PBS in a heterogeneous system is proposed. Starch-g-PBS is accomplished by a conjugating reaction in chloroform at room temperature between hydroxyl groups of starch and carboxylic acid terminal groups of PBS by using N-N′-dicyclohexylcarbodiimide (DCC) conjugating agent. The grafting of PBS at both primary alcohol and secondary alcohol of starch is as high as 20–30% as confirmed by 1H NMR and HMBC 2D NMR. The grafting of PBS results in a drastic changes of the crystallization as seen from the decrease in size of spherulite. The starch-g-PBS is a good compatibilizer between PBS and starch by promoting strong interfacial adhesion of the blend as evidenced from the improvement of modulus (2 times increase) and the miscibility of the blend in SEM images.