chaPter 7 nanomaterials: Properties
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with other elements. Previous work has shown an increase of the
Tg, modulus, and strength.
In addition to uniform dispersion of CNTs within a polymer matrix,
a crucial aspect for providing optimal reinforcement is to properly
orient the CNTs. Because of their aspect ratio, CNTs possess highly
anisotropic mechanical properties. To take advantage of their loadcarrying efficiency along the axial direction, it is essential that CNTs
are well aligned within the matrix. Several methods have been used
to align the CNTs. Extrusion is a popular technique, in which a
polymer melt reinforced with CNTs is extruded through a die and
drawn under tension before solidification. Polystyrene nanocomposites filled with MWCNTs have been produced in this manner.
Compared with a pristine sample, the modulus of the aligned
MWCNT/polystyrene composite increased as much as 49%, comFigure 7.49
Polymers used for the functionalization and solubilization of CNTs. (Courtesy of Yi Lin, Mohammed J.
Meziani, and Ya-Ping Sun, J. Mater. Chem., 17,
2007, 1143.)
PVA
OH
OH
O
C
x
n
n
n
m
m
PS OH
PVK OH
PS NH2
PS OH '
PI-NH 2
PI OH
EVOH
PPEI-EI
OH
N
H
N
O
n
m
OH
OH
NH 2
H 2 N
NH 2
F 3 C CF 3
O
O
n
m
n
m
n
m
m
n
N
OH
O
O
O
O
O
O
N
N
O
OH
O
F 3 C CF 3
O
m
O
O
O
O
O
N
N
F 3 C CF 3
O
O
O
O
N
N