In situ dual crosslinking strategy to improve the physico-chemical properties of thermoplastic starch

• Published in: Carbohydrate polymers 2021-10, Vol.269, p.118250-118250, Article 118250
• Main Authors: Peidayesh, Hamed, Heydari, Abolfazl, Mosnáčková, Katarína, Chodák, Ivan
• Format: Article
• Language: English
• Subjects: Covalent bond; Epichlorohydrin; In situ crosslinking; Melt processing; Thermoplastic starch
• ISSN: 0144-8617; 1879-1344
• DOI: 10.1016/j.carbpol.2021.118250

This study is focused on enhancing the stability of mechanical and chemical properties of thermoplastic starch (TPS) by dual crosslinking strategy through melt processing conditions. The dually crosslinked TPS was prepared by in situ reaction of starch, glycerol, and epichlorohydrin (ECH), resulting in both noncovalent and covalent bond formation. The TPS was characterized by tensile testing, dynamic mechanical analysis (DMTA), rheology, and solubility in water. A substantial increase in tensile strength, Young's modulus, insoluble portion, and stability in water for dually crosslinked TPS was observed in comparison with conventional TPS. The rheology results indicated that the ECH induced the formation of 3D networks and significantly limited the chain mobility of the melted TPS, resulting in an extended relaxation process, which was also verified by DMTA. The suggested strategy avoids any chemical modification pretreatment of starch for introducing covalent bonds into TPS before one-step mixing using the melt processing technique. •Thermoplastic starch is crosslinked by dual noncovalent and covalent bond.•Epichlorohydrin is reacted by starch and glycerol in melt processing conditions.•Mechanical properties are reinforced by noncovalent and covalent bond combination.•Dually crosslinked thermoplastic starch is more stable under an aqueous environment.•The characteristics of the product are dependent on reaction conditions.