Civil Engineering Reference
In-Depth Information
enable the future use of these hybrid nanocomposites as multifunctional materials for
wound care management [161].
6.4.1.2
CNR and Ceramic Nanoparticles
h e properties of polymeric materials can be tailored by the addition of i llers of vary-
ing surface chemistry and aggregate size/aspect ratio to suit the application concerned.
Nanometric particles can be classii ed according to their morphology, i.e., rod-like,
platelet-like, and spherical nanoparticles. Due to their high aspect ratio and their
impermeable character, clay platelets, for example, are expected to induce signii cant
property increase when they are dispersed within a polymer matrix, especially if com-
bined with other specii c i llers. A variety of clays, such as montmorillonite and organo-
clays, have been used to obtain unusual nanocomposites, by exploiting the ability of
the clay silicate layers to disperse into polymer matrices [162-166]. Inorganic i llers
can greatly enhance the properties of cellulose. White
et al.
recently reported cellulose/
clay composites with superior thermal and mechanical properties [167]. Moreover, the
potentials of clay nanoparticles were recently combined with the unique properties,
including higher water holding capacity, higher crystallinity, greater tensile strength,
an ultrai ne i ber network and the ability to be moulded into various shapes during
production, of the bacterial cellulose and BC/montmorillonite (BC/MMT) composites
were prepared by impregnation of BC sheets with MMT suspension [106]. h e physico-
mechanical and thermal properties of the composites were signii cantly improved com-
pared to those of pure BC. Moreover, the BC composite also showed improvements in
water release rate compared to pure BC which is an important feature for BC applica-
tions in the medical i eld.
Cellulose structures and nanoclays were also combined in a polymer matrix. A series
of nanocomposite i lms based on natural rubber (NR), pristine Na
+
montmorillon-
ite, and cellulose whiskers was prepared. h e mechanical properties were signii cantly
improved upon i ller addition. Both dynamic mechanical analysis and tensile tests
results indicated that the simultaneously introduced montmorillonite and cellulose
whiskers into NR could greatly improve the rubbery tensile modulus. Moreover, the
strong decrease of the magnitude of the loss angle upon addition of whiskers was attrib-
uted to strong adhesion between the i ller and the matrix. Moreover, the tortuosity val-
ues calculated from the permeability and dif usion coei cients, respectively, indicated
that the simultaneous use of montmorillonite and cellulose whiskers could greatly slow
down the gas dif usion rate in NR. h e authors proved that the formation of montmo-
rillonite/cellulose whiskers subassembly should be responsible for this synergism ef ect
useful for the i nal applications in some dif erent industrial i elds.
6.4.1.3
CNR and Carbon-Based Nanoparticles
Recently, researchers have shown an increased interest in carbon-based particles/cellu-
lose formulation development, in which carbon particles are used to enhance mechani-
cal properties and electrical conductivity simultaneously [168]. Regenerated cellulose/
graphene composite i lms had been recently prepared by dispersing graphene into
cellulose solution and then casting the solution onto glass [169]. Graphene, the two
nano-dimensional counterpart of carbon nanotube, consists of one atom-thick layer of
