Influence of formamide and water on the properties of thermoplastic starch/poly(lactic acid) blends

Starch as an inexpensive and renewable source has been used as a filler for environmentally friendly plastics for about 2 decades. In order to improve the compatibility between hydrophilic starch granules and hydrophobic Poly(lactic acid) (PLA), glycerol, formamide, and water are used alone or combined as plasticizers for starch to enhance the dispersion and the interfacial affinity in thermoplastic starch (TPS)/PLA blend. And the properties of TPS/PLA blends are investigated through microscopy (SEM), rheological, thermogravimetric analysis (TGA), Fourier transform infrared (FT-IR), tensile testing, and Dynamic mechanical thermal analysis (DMTA). In the presence of water and formamide, the plasticization of starch can be improved dramatically. At the same time, SEM can detect a homogeneous TPS/PLA blends. With increasing the dispersion between TPS and PLA, the blend becomes more thermal stability as shown in TGA. It also proves that PLA degrades in the presence of water during melt processing. In addition, FT-IR spectroscopy proves that formamide and water can improve the interaction between TPS and PLA. The tensile testing and DMTA suggest that the compatibility between TPS and PLA is improved in this paper.