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Poly(vinyl alcohol) (PVA) composite films using poly(vinyl pyrrolidone) (PVP) and sodium dodecyl sulfate (SDS)-covered, well dispersed single wall carbon nanotubes (SWNT) exhibit significant improvement in tensile strength and modulus as compared to the control PVA and PVA/PVP/SDS films. The evidence of load transfer to the nanotubes in the composite film has been obtained from the shift in the Raman SWNT D* band peak position.

An optically homogeneous solution/dispersion of single-wall carbon nanotubes (SWNTs) in oleum has been used to form isotropic films exhibiting fibrillar morphology. Tensile modulus, strength, and strain to failure of the film are 8 GPa, 30 MPa, and 0.5%, respectively. The electrical conductivity in the plane of the film is 1 × 105 S/m.

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Polyacrylonitrile (PAN) fibers containing 10 wt.‐% single‐walled carbon nanotubes (SWNTs) exhibit a 100 % improvement in tensile modulus and reduced thermal shrinkage and polymer solubility. A 40 °C increase in glass transition temperature as compared to the control PAN fiber is also observed (see Figure). SWNT anisotropy has been observed using infrared spectroscopy.

Single wall carbon nanotube films (bucky paper) have been prepared using aqueous dispersions containing 0, 3, 6, and 10 M nitric acid. With increasing nitric acid concentration, film tensile strength increased from 10 to 74 MPa, tensile modulus from 0.8 to 5.0 GPa, while in-plane dc electrical conductivity decreased from 3 × 10 4 S/m to 1.2 × 10 4 S/m. In-plane storage modulus exhibited no decrease in the measured temperature range (room temperature to 200°C). Raman spectroscopy showed that nitric acid treatment results in the loss of the small diameter tubes. This was consistent with the X-ray diffraction observation, which showed that with increasing nitric acid concentration, (10) and (11) SWNT d spacings increased from 1.23 to 1.29 nm and from 0.74 to 0.87 nm, respectively. Morphological changes in the film have been monitored using scanning electron microscopy.

The use of carbon nanotubes for piezoresistive strain sensors has acquired significant attention due to its unique electromechanical properties. In this comprehensive review paper, we discussed some important aspects of carbon nanotubes for strain sensing at both the nanoscale and macroscale. Carbon nanotubes undergo changes in their band structures when subjected to mechanical deformations. This phenomenon makes them applicable for strain sensing applications. This paper signifies the type of carbon nanotubes best suitable for piezoresistive strain sensors. The electrical resistivities of carbon nanotube thin film increase linearly with strain, making it an ideal material for a piezoresistive strain sensor. Carbon nanotube composite films, which are usually fabricated by mixing small amounts of single-walled or multiwalled carbon nanotubes with selected polymers, have shown promising characteristics of piezoresistive strain sensors. Studies also show that carbon nanotubes display a stable and predictable voltage response as a function of temperature.

Highly sensitive single-wall carbon nanotube/graphite nanoplatelet (SWCNT/GNP) hybrid thin-film sensors are developed, which possess the unique capability for self-temperature compensation. This unique property in combination with their high gauge sensitivity and large reversible extensibility promises the SWCNT/GNP hybrid thin film piezoresistive sensors for a wide range applications, such as in man-machine interaction and body monitoring.