University of Freiburg - Freiburg Institute for Advanced Studies, Germany
pp. 376 - 379
Keywords: cellulose, bionanocomposite, hydrophobization, blending
Cellulose fibers are advantageous reinforcing materials for bio-based composites because of their availability and good mechanical properties. Several chemical processes have been developed to turn the native fibers into micro- (MFC) or nanofibrillated (NFC) cellulose fibers. Further surface modification of the micro- and nanofibrillated cellulose is done by the deposition of hydrophobic nanoparticles onto the fiber surface, allowing to tune the required hydrophobicity of the cellulose additives and to make them compatible with, e.g. PLA. The fibrillated cellulose fibers were modified by an in-situ reaction with styrene maleic anhydride, ammonium hydroxide and plant wax under aqueous environment. The possibility for blending the modified fibers were first examined with oscillatory rheological experiments: it has been observed that homogeneous mixtures of PLA/MFC can be obtained depending on the strain and frequency regimes in the rheometer. Optimum concentrations of modified fibers to obtain good mixtures were at around 1 to 2 %. Finally, the modified fibers could be successfully mixed with the polymer matrix during an extrusion and injection moulding experiment. The standard mechanical properties of the PLA/MFC nanocomposites were determined from a stress-strain experiment, where it is seen that the reinforcement of the polymer matrix is optimum at 1 % fiber content.