New biocomposites based on thermoplastic starch and bacterial cellulose

Bacterial cellulose, produced by Acetobacter Xylinum, was used as reinforcement in composite materials with a starch thermoplastic matrix. The composites were prepared in a single step with cornstarch by adding glycerol/water as the plasticizer and bacterial cellulose (1% and 5% w/w) as the reinforcing agent. Vegetable cellulose was also tested as reinforcement for comparison purposes. These materials were characterized by different techniques, namely TGA, XRD, DMA, tensile tests, SEM and water sorption assays. All composites showed good dispersion of the fibers and a strong adhesion between the fibers and the matrix. The composites prepared with bacterial cellulose displayed better mechanical properties than those with vegetable cellulose fibers. The Young modulus increased by 30 and 17 fold (with 5% fibers), while the elongation at break was reduced from 144% to 24% and 48% with increasing fiber content, respectively for composites with bacterial and vegetable cellulose.