Study on the properties of ethylenebisformamide and sorbitol plasticized corn starch (ESPTPS)

A mixed plasticizer (ethylenebisformamide and sorbitol) was used to the preparation of thermoplastic starch (TPS). And the other three TPSs were prepared as a contradistinction, including glycerol plasticized starch (GPTPS), ethylenebisformamide plasticized starch (EPTPS), and sorbitol plasticized starch (SPTPS). FT-IR expressed that the microcosmic chemical environments of the group in all these TPSs mentioned above shifted to lower frequency compared with the native corn starch, which indicated that, the strong and stable hydrogen bond had been formed between plasticizers and starch. By scanning electron microscope (SEM) native corn starch granules were proved to transfer to a continuous phase. After being stored for 2 weeks at ambient atmosphere, the mechanical properties of these TPSs were investigated and a comprehensive tensile stress and elongation at break of ESPTPS was obtained better than that of EPTPS, SPTPS, and GPTPS. X-ray diffraction (XRD) showed that the typical A-style crystallinity in the native corn starch has been destructed. On the other hand, water resistance of ESPTPS was better than the conventional GPTPS. ESPTPSs proved to be having good thermal stability by thermogravimetric analysis (TGA), and the decomposition temperature was increased with the increase of the sorbitol content. Tg (detected by dynamic thermal mechanical analysis (DTMA)) of ESPTPSs was lower than that of EPTPS and SPTPS.