Preparation And Characterization Of Novel Thermoplastic Starches

Novel thermoplastic starch (TPS) resins were successfully prepared by incorporation of bacterial cellulose (BC) nanofibers and polyvinyl alcohol (PVA) resins during their gelatinization processes. In which, BC nanofibers were metabolized by Acetobacter xylinum in granular sugar culture media at the optimum cultivation condition. After blending PVA in TPS during their gelatinization processes, the tensile strength (σf) and elongation at break (εf) values of TPSxPVAy specimens improved significantly and reached a maximal value, as their PVA contents approach an optimum content. After incorporation of BC fibers during the gelatinization processes of TPSxPVAyBCz resins, their σf and εf values improved significantly with the increase in the BC contents initially and reached an maximal value, respectively, as their BC contents approach an optimum but very small value, In which, improvement over40%in σf and εf values of TPS1PVA1/12BC1/5000specimens was found after addition of only0.02part BC per hundred part of corn starch. As evidenced by wide angle X-ray diffraction and thermal analyses of the corn starch specimens, TPS, TPSxPVAy and TPSxPVAyBCz specimens, the natural crystalline structure of corn starch molecules were dismantled after their gelatinization processes. These results clearly suggest that excellent tensile properties of novel TPS can be prepared by addition of proper amounts of PVA resins and appropriate but very small amounts of BC nanofibers during the gelatinization processes of corn starches.