Civil Engineering Reference
In-Depth Information
hemp nanoi bers as reinforcing agents for biocomposites. Nanoi bers were only par-
tially dispersed in the polymers and therefore resulted in low mechanical properties
compared to those predicted by theoretical calculations. Morphological analyses of
sisal whiskers by Siqueira and his coworkers [168] by using N-Octadecyl isocyanate
(C
18
H
37
NCO) as the grat ing agent show the homogeneity and nanometric dimensions
of sisal whiskers (Figure 11.23).
Besides enhancing compatibility of nanocellulose with nonpolar polymers and
improving mechanical properties, the purpose of chemical modii cation is to add extra
functionality to nanocellulosic materials. For instance, h omas
et al.
[170] reported
that positively charged amine-functionalized MFC is said to be antimicrobially active
in biomedical applications. Andresen and Stenius [164] also added extra functional-
ity to MFC i lm by covalently grat ing the cellulose with octadecyldimethyl(3-trime-
thoxysilylpropyl)ammonium chloride (ODDMAC). When the atomic concentration
of ODDMAC nitrogen on the i lm surface was 0.14% or higher, the surface-modii ed
MFC i lms showed antibacterial activity against both Gram-positive and Gram-negative
bacteria, even at very low concentrations of antimicrobial agent on the surface, killing
more than 99% of
E. Coli
and
S. Aureus
. h e chronological order of events for various
modii cations of nanocellulose can be seen in Table 11.3.
Figure 11.23
SEM image of sisal MFC: (A) optical microscopy image of sisal MFC and (B) TEM of sisal
whiskers (C and D) [168].
