Melt-Processing of Biopolymer Composites with Nanocellulose Additives

Abstract

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. These nanocomponents are believed to even have stronger reinforcing capacity because of surface interaction effects at the nanoscale and formation of a fine web structure. During further processing of fibrillated cellulose in combination with a biopolymer matrix, however, there is evidence of agglomeration due to the hydrophilic nature of the fibers and incompatibility with the polymer matrix. In our approach, surface modification of the micro- and nanofibrillated cellulose is done by the in-situ deposition of hydrophobic nanoparticles onto the fiber surface, allowing to tune the required hydrophobicity of the cellulose additives and to make them compatible with extrusion applications, as demonstrated for PLA biopolymers.