For industrial production of polymer-CNC nanocomposites,
melt-processing appears to be the most economical method. Melt
processing of CNCs tend to result in CNC-aggregates and phaseseparation
from the matrix, impeding improvements in materials
properties. Several approaches to overcome this problem are to
wrap CNCs within another polymer, small-molecule CNC modifications
and grafting strategies [6]. In one example, a polyvinyl
alcohol (PVA)-CNC aqueous dispersion was prepared and then coextruded
with PLA. However, the unmodified CNCs were located
predominantly within the co-continuous PVA phase [24]. Good
reinforcement by CNCs of the matrix was achieved by silanization
of CNCs in citrate buffer which were then dried before being melt
blending with PLA [25]. CNCs suspended in toluene after solvent
exchange were modified by ‘grafting from’ reactions with L-lactide.
The resulting CNC-g-PLA was melt-blended with PLA and good
mechanical properties were achieved [17].