abstract
The aim of this study was to investigate if cellulose nanofiber (CNF) gels with high water
contents can be processed to nanocomposites with starch powder using continuous
twin-screw extrusion and to improve the mechanical properties and moisture sensitivity
of thermoplastic starch. Nanocomposites with 0, 5, 10, 15 and 20 wt.% cellulose nanofiber
content were prepared. The characterization methods were conventional tensile testing,
UV/Vis spectroscopy, scanning electron microscopy and moisture absorption. The cellulose
nanofiber gel with high water content was mixed with starch powder, fed to the extruder
as powder, performing the gelatinization of starch as well as the mixing of CNF in one step.
The microscopy study showed that the CNF aggregated during the process and that the
screw configuration needs to be more distributive and dispersive to get homogeneous
material. The results showed that the addition of CNF improved the mechanical properties
and had a positive effect on moisture uptake of the thermoplastic starch. Also, the translucency
of the TPS/CNF composite films remained, even with high CNF content (20 wt.%).