“…However, the global view from experimental observations clearly demonstrates that hetero-junction CNTs are constructed of two CNTs with different chiralities, which connect together by a kink with pentagon-heptagon cell pairs (also known as Stone-Wales defects) in the bent locations of the connection [34,40] (see Figure 6.2(a)). These kinks, whose existence and size seem to be noticeably effective on the mechanical properties of hetero-junction CNTs, are generally divided into two groups, straight and bent connections, as illustrated in Figure [47] bending angle about 36 ∘ ) [45] and small-angle connections (with bending angle about 12 ∘ ) [31,34]. There is also another classification of the kinks that depends on their corresponding homogeneous tubes' configurations, which build the hetero-junction CNTs.…”