Preparation of a new dialdehyde starch derivative and investigation of its thermoplastic properties

In order to obtain thermoplastic starch plastics with improved properties, a novel method of starch modification was developed in this study. Starch derivatives were prepared using the following procedures: pea starch was first oxidized to make dialdehyde starch (DAS) by sodium periodate under mild conditions, and this was then acetalized with glycol to give Gly-ADS. The modified starch was characterized by FT-IR, 1H-NMR, TG, DSC, and XRD. The TG curves indicated that the thermal stability of Gly-ADS was better than that of DAS. The glass transition temperature of Gly-ADS with 95% carbonyl content (Gly-ADS95) was 97 °C by DSC. Although the intrinsic viscosity of DAS was less than that of pea starch, thermoplastic Gly-ADS (TPGly-ADS) exhibited good mechanical properties. The influence of moisture absorption on the mechanical properties of TPGly-ADS was also investigated. The results showed that TPGly-ADS possesses improved water resistance: the highest moisture absorption of TPGly-ADS95 was about 11%, and the tensile strength and the elongation at break were 18.1–14.6 MPa and 5.3–18%, respectively.