Effect of a Complex Plasticizer on the Structure and Properties of the Thermoplastic PVA/Starch Blends

The mixture of glycerol (GL) and urea (UR) were used as a complex plasticizer for the thermoplastic PVA/starch blends (TPPS). The interaction between the glycerol/urea complex and TPPS was investigated by differential scanning calorimetry (DSC) and thermal gravity (TG). Results showed that the complex of glycerol and urea could form more stable and strong hydrogen bonds with water and PVA/starch molecules than the single plasticizer such as glycerol. The PVA/starch granules were proved to be conversed into a continuous phase by scanning electron microscope (SEM). The rheological, mechanical and crystalline properties of TPPS were also studied by Haake rheometer, tensile testing and X-ray Diffraction (XRD), respectively. Results showed that TPPS plasticized by the mixture of glycerol/urea (20/10 wt.%) had better rheological and mechanical properties than that plasticized by single glycerol. Moreover, the complex plasticizer increased the tensile stress and elongation at break of TPPS to 7.83 Mpa and 203%.