Carbon nanotube-reinforced composites orientations

Narh, K. A. Zhu, L. Numerical simulation of the effect of nanotube orientation on tensile modulus of carbon-nanotube-reinforced polymer composites. Polym. Int. 53, 1461-1466 (2(X)4). 

The properties of carbon nanotubes are not only sensitive to their diameter and chirality but are also highly anisotropic. The stiffness, strength and electrical, magnetic and optical properties of the nanotube-reinforced composites strongly depend on the orientations of the nanotubes. Therefore, it is crucial to obtain the controllable alignment of the nanotubes in the nanocomposite. 

Zhang Q, Wang Y, Fu Q (2003) Shear-indnced change of exfoliation and orientation in polypro-pylene/montmorillonite nanocomposites. J Polym Sci B Polym Phys 41 1-10 Zhang WD, Shen L, Phang lY, Liu T (2004) Carbon nanotubes reinforced nylon-6 composite prepared by simple melt-compounding. Macromolecules 37 256-259 Zhao Y, Abdullayev E, Vasiliev A, Lvov YM (2013) Halloysile nanotubule clay for efficient water purification. J Coll Interface Sci 406 121-129... 

Another technique, known as the dry powder mixing method, has been employed by Cooper et al. to produce nanotube-reinforced polymethylmethacrylate (PMMA) composites [61]. Like most of the currently used fabrication methods for nanotube-based polymer composites, this technique is a combination of several protocols including solution-evaporation, sonication, kneading, and extrusion. More specifically, these workers used ultrasonic techniques to blend carbon nanotubes with PMMA particles, and the blend was later extruded to orient the nanotubes. Yang et al. [62] prepared small-scale batches of ABS nanocomposites without the use of solvents or ultrasonic techniques with good dispersion of the nanotubes. 

Carbon nanotnbes are regarded as ideal filler materials for polymeric fiber reinforcement dne to their exceptional mechanical properties and cylindrical geometry (nanometer-size diameter). Polymer chains in the vicinity of carbon nanotubes (interphase) have been observed to have a more compact packing, higher orientation, and better mechanical properties than bulk polymers due to the carbon nanotube polymer interaction. The existence of interphase polymers in composite fibers, their strnctnral characterization, and fiber properties are summarized and discussed in the literature (Liu and Satish 2014). Besides improvements in tensile properties, the presence of carbon nanotubes in polymeric fibers also influences other factors (thermal stability, thermal transition temperature, fiber thermal shrinkage, chemical resistance, electrical conductivity, and thermal conductivity). 

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