Structural and Thermomechanical Study of Plastic Films Made from Cassava-Starch Reinforced with Kaolin and Metakaolin

Abstract

The structural and thermomechanical properties of starch-based plastic films reinforced with kaolin and metakaolin have been studied by various techniques (X-ray diffraction, IR-TF spectroscopy, scanning electron microscopy, tensile tests, and thermal resistance). The results obtained showed that kaolin, an inert material, prevents the starch from losing its granular structure and to solubilize during the heating, generating plastic films of low Young's modulus (7 MPa). On the other hand, metakaolin, an amorphous and dehydroxylated material obtained after heating of kaolin at 700˚C for 1 hour, substantially improves the thermomechanical properties of the plastic films. The Young's modulus increases from 19 MPa to 25 MPa while the thermal resistance increases from 90˚C to 120˚C. This was attributed to good dispersion of the metakaolin in the polymer matrix after the loss of the granular structure of the starch during heating.