Method for preparing thermoplastic compositions based on plasticized starch and resulting compositions

The subject matter of the present invention is a method for preparing a starch-based thermoplastic composition, comprising the following steps: (a) selecting at least one granular starch and at least one organic plasticizer for this starch, (b) preparing a plasticized composition by thermomechanically mixing this starch and this plasticizer, (c) optionally incorporating at least one functional substance carrying functions comprising an active hydrogen, (d) incorporating at least one bonding agent carrying at least two functional groups capable of reacting with molecules carrying functions comprising an active hydrogen, and optionally (e) heating the mixture to a temperature sufficient to cause the bonding agent to react with the plasticizer and with the starch and/or the functional substance, it being possible for steps (d) and (e) to be carried out simultaneously, and also a starch-based thermoplastic composition that can be obtained by means of this method.