Biocomposites from wheat straw nanofibers: Morphology, thermal and mechanical properties

The reinforcing potential of cellulose nanofibers obtained from agro-residues was investigated in a starch-based thermoplastic polymer. Cellulose nanofibers were isolated from wheat straw by a chemi-mechanical technique and determined to have diameters in the range of 10-80 nm and lengths of several thousand nanometers. Thermal stability of the fibers was investigated using thermogravimetric analysis and found that the degradation temperature of the fibers is increased after each step of the treatment. The nanocomposites from the wheat straw nanofibers and the thermoplastic starch were prepared by the solution casting method. Their thermal and mechanical performance were also evaluated and compared with the pure thermoplastic starch using thermogravimetric and dynamic mechanical analysis, and tensile testing. The scanning electron microscopy images of the nanocomposites showed a uniform dispersion of the nanofibers in the polymer matrix. The tensile strength and modulus of the nanocomposite films revealed significantly enhanced properties compared to the pure thermoplastic starch. The glass transition of the nanocomposites was shifted to higher temperatures with respect to the pure thermoplastic starch. (c) 2007 Elsevier Ltd. All rights reserved.