Preparation of Poly (lactic acid)/Etherified Starch Composites

Poly (lactic acid) (PLA) is one of the most promising biodegradable materials with excellent mechanical properties, but the disadvantages of stiffness, poor thermal stability, and high costs limit its applications in general use plastics such as industrial packaging and agriculture films. In present work, biodegradable PLA/starch composites are prepared from PLA and etherified starch (EST) by extrusion and uniaxial orientation processing with a pretreated mixing procedure under a programmed temperature. The products are examined using Fourier transform infrared (FTIR) spectroscopy technique. The results revealed that small amount of PLA molecules have strong interaction with EST which may be ascribed to the esterification between the terminal carboxyl groups of PLA and hydroxyl groups in EST. The morphological properties observed by scanning electron microscopy (SEM) technique confirmed that the composites with a pretreatment procedure had much better dispersion and homogeneity of starch in the PLA matrix than the composites without the pretreatment procedure. Consequently, an improvement in mechanical properties has been achieved. Comparing with the samples without the pretreatment procedure, the mechanical performances such as tensile strength, elongation-at-break and modulus of the composites with a pretreatment procedure were significantly improved. This approach is identified as a reasonable method to produce commercial PLA/starch composites with economical feasibility