Chemistry Reference
In-Depth Information
u, v
and
z
directions, is achieved using shape function
[N]
for each ele-
ment, such that the total potential energy becomes:
(44)
where
[B]
is the matrix containing the derivation of the shape function,
and
[d]
is a vector containing the displacements.
9.3 CARBON NANO TUBES (CNT): STRUCTURE AND
PROPERTIES
A Carbon Nanotube is a tube shaped material, made of carbon, having
length-to-diameter ratio over of 100,000,000:1, considerably higher than
for any other material. These cylindrical carbon molecules have strange
properties such as extraordinary mechanical, electrical properties and ther-
mal conductivity, which are important for different fields of materials sci-
ence and technology.
Nanotubes are members of the globular shape structural category.
They are formed from rolling of one atom thick sheets of carbon called
graphene, which cause to hollow structure. The process of rolling could
be done at specific and discrete chiral angles, as nanotube properties are
dependent to the rolling angle. The single nanotubes physically line up
themselves into ropes situation together by Vander Waals forces.
Chemical bonding in nanotubes describes by orbital hybridization. The
chemical bonding of nanotubes is constituted completely of sp
2
bonds,
similar to those of graphite, which are stronger than the sp
3
bonds found in
diamond, provide nanotubes with their unique strength.
9.3.1 CATEGORIZATION OF NANOTUBES
Carbon nanotube is classified as single walled nanotubes (SWNTs),
multiwalled nanotubes (MWNTs) and Double walled carbon nanotubes
(DWNTs).
