Page 616 - Book Hosokawa Nanoparticle Technology Handbook

APPLICATIONS 40 EVALUATION AND APPLICATIONS OF DISPERSING CNT IN THE POLYMERS
3
shown to be caused by the elimination of the micro- roughly estimated as 4.1 10 26 m , which gives its
pores. The micropores instantaneously disappeared cubic root as 3.5 nm. Based on this estimation, one
at the moment of the completion of the condensation nanoscopic bubble is considered to contain only a few
of the residual silanol groups. That is, the completion decades of water molecules. Interestingly, even such a
of the siloxane bondings simultaneously blocked the small number of the enclosed gaseous molecules can
generated water molecules from being fugitive from form entirely isotropic spherical geometry of the
the silica matrix and the enclosed water molecules nanoscopic balloons.
ubiquitously formed balloons all over the silica
matrix. The preheating for the reinforcement is con- References
sidered to contribute to the densification of the silica
matrix. The siloxane network moderately densified [1] L. Pei, K. Kurumada, M. Tanigaki, M. Hiro and
by preheating would also be advantageous in pre- K. Susa: J. Colloid Interface Sci., 284, 222–227
venting the generated water molecules from having (2004).
way out of the silica matrix and form the nanoscale [2] L. Pei, K. Kurumada, M. Tanigaki, M. Hiro and
balloons.
Finally, the author estimated the number of water K. Susa: J. Mater. Sci., 39, 4045–4047 (2004).
molecules enclosed in a single nanoscale bubble. [3] L. Pei, K. Kurumada, M. Tanigaki, M. Hiro and
Assuming that the final inner pressure inside the K. Susa: J. Mater. Sci., 39, 663–665 (2004).
nanoscale bubble levels off at the atmospheric pressure, [4] K. Kurumada, N. Kitao, M. Tanigaki, M. Hiro and
the occupied volume by a single gaseous molecule is K. Susa: Langmuir, 20, 4771–4773 (2004).

APPLICATION 40

40 EVALUATION AND APPLICATIONS OF DISPERSING CARBON NANOTUBE IN THE
POLYMERS

1. Carbon nanotube 2. Fracture model of agglomerates of carbon
nanotube
The carbon nanotube, abbreviated as CNT hereafter,
was found by Iijima in 1991 and has drawn much Palmgren explained how to disperse carbon black
attention as one of the remarkable new materials in agglomerates into the matrix rubber material. As
the field of nanotechnology [1, 2]. Lately, many inten- shown in Fig. 40.1 [10], he proposed the following
sive CNT studies in very diverse applications were four steps [11].
reported. CNT is expected to be applied in the devel-
opment of various new materials. 1. Crush and micronize the large CNT agglomer-
There are two main streams in the research and ates into smaller ones by impactions and other
development of CNT. One of them is to design and pre- external forces.
pare a piece of CNT with high accuracy and advanced
control on its orientation; and, the other is to conduct 2. Mix the smaller CNT agglomerates into the
massive production of CNT. As an example of the matrix material.
former applications, CNT is developed to be used as 3. The mixture of CNT agglomerates and the
the electron emission source of Field Emission matrix material is further micronized by shearing
Display (FED), cantilever of SEM, negative elec- force to disperse and deagglomerate CNT fiber.
trode material of Li battery, wiring of LSI, electronic
devices and so on [3–6]. On the other hand, a large 4. Repeat the process until the deagglomerated
amount of CNT is required for making hydrogen CNT fiber is well distributed and diffuses into
storage materials and resin composite materials the matrix material.
[7–9]. The ability to massively produce CNT plays
an important role on its cost reduction for general 3. Dispersion of CNT by an extruder
applications. In this section, the dispersion of CNT
in the molten resin, a common difficult task, is To disperse CNT into the molten resin, the biaxial
introduced. extruder with high kneading power is used in

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