||In this study, the sebacic acid(SA) and maleic anhydride(MA) were used to modify tapioca starch(ST), then the thermoplastic polyurethane(TPU) and glycerol (GA) were added into modified starch, to prepare a new blends. The mechanical properties, thermal properties and physical properties of blends were studied. This investigation was divided into two parts.
In part 1, the 2g of SA was dissolved into alcohol or glycerol, and then the tapioca starch was modified by this solution. And then different amounts of TPU (0g, 50g ,100g, 150g) was added into modified starch to prepare the blends by using single-screw extruder. In this study, the blends were named as AlTPU as the SA was dissolved in alcohol. However, the blends were named as STTPU as the SA was added into starch directly. The FT-IR patterns indicated that the characteristic peak of C=O in ester was observed at 1720cm-1. It proved that SA was reacted with glycerol by esterification and used to plasticize blends during extrusion. The stress-strain test show that the tensile strength at break of STTPU were higher than those of AlTPU blends. And the tensile strength could be increased from 2 MPa to 6 MPa as the strain of blends below was 20%.
In part 2, various amounts (0.1, 0.3, 0.5g) of MA or 2g of SA was added into glycerol directly, and then mixing with 250 g of ST and 100 g of TPU to prepare new blends by using single screw extruder. The FT-IR patterns indicated that the characteristic peak of C=O in ester observed at 1720cm-1. It proved that SA reacted with glycerol by esterification.
As the blends contain 0.3 g of MA, the strain of blends decreased from 325% to 200%. However, the stress of blend markedly increased from 5.75 MPa to 11.3 MPa. It was because that the MA react with GA or starch for the reason of esterification. On the other hand, the esterification effect caused the multi-molecules GA to form and increased the thermal resistance property. For this reason, the multi-molecules of GA could be catched in blends to increase the processing ability of blends. The melt flow index (MFI) of blend was increased from 2.775 g/10min to 8.790 g/10min by adding MA.