Civil Engineering Reference
In-Depth Information
BC
Immersion of BC membrane
in the solution
BC-NH
2
NH
2
NH
2
Acetone
NH
2
Thermal Treatment
2h
T=110°C
Si
H
3
CO
OCH
3
OCH
3
Orbital stirring
5h at 25°C
Figure 2.14
General procedure for BC chemical grat ing using aminopropylsilane. SEM images of
BC membrane and its l exibility before (BC) and at er (BC-NH
2
) chemical grat ing. Reproduced with
permission from [114].
nanocomposites have been prepared by distinct approaches, as melting-mixing [118],
hot pressing [120], impregnation and drying [119], and solvent casting [121]; and are
mainly used for packaging applications. For example, multicomponent nanocompos-
ite i lms of thermoplastic starch, chitosan and BC (as well as nanoi brillated cellulose)
were set by solvent casting of water-based suspensions of the three polysaccharides
[121]. h ermoplastic starch displayed an important role on the thermal stability of the
i lms because it is the most stable polysaccharide; however it has an undesirable impact
on their mechanical performance and transparency. On the other hand, the addition
of chitosan improves considerably the transparency (up to 50% transmittance for 50%
of chitosan, in respect to the amount of starch), mechanical performance and antimi-
crobial properties, but decreased their thermal stability. As expected, the incorporation
of cellulose nanoi bers had the strongest positive inl uence on the mechanical proper-
ties of the materials. In another study, the ef ect of the addition of BC to commercial
starch Mater-Bi® (starch/poly(ethylenevinyl alcohol)), has been investigated [122]. BC
was easily incorporated in the Mater-Bi matrix, by blending in a twin-screw extruder,
resulting in nanocomposites with improved mechanical (an increment of up to 100%
on the Young modulus for 10% of BC) and thermal properties.
Hemicelluloses, specii cally unmodii ed and enzymatically debranched rye arabi-
noxylans, were also studied for the preparation of optically transparent composite i lms
reinforced with BC for potential application as food packaging biobased i lms [123].
h e nanocomposites were prepared by mixing a BC dispersion with the arabinoxylan
solution in dif erent proportions followed by solvent casting. h e reinforcement with
BC decreased the moisture sorption and increased the stif ness and strength of the i lms.
BC/alginate nanocomposites have also been ei caciously prepared and tested in dis-
similar applications, including biomedical devices [124], separation membranes [125]
