Fabrication and Nanocompression Testing of Aligned Carbon‐Nanotube–Polymer Nanocomposites

Abstract

The exceptional electronic, thermal, and mechanical properties of carbon nanotubes (CNTs) have motivated extensive research on their manufacturing and applications. At bulk scales, there is particular interest in property enhancements by adding CNTs to polymers to make composite materials. Most work on CNT-based composites presented in the literature to date has focused on dispersion of single- or multiwalled CNTs (SWNTs or MWNTs) in the matrix; however, bulk CNTs embedded in a polymeric matrix tend to form aggregates that are not only poorly adhered to the matrix but also concentrate stresses, compromising the effect of the CNTs as reinforcement. [1] On the other hand, establishing order and alignment among CNTs within a composite matrix offers significant further potential to harness the properties of individual CNTs at bulk scales by realizing the anisotropic properties of CNTs in desired directions, and by enabling packing and dispersion of CNTs at much higher volume fractions than in tangled configurations. In this work, CNT–polymer composites are manufactured by wetting as-grown arrays of vertically aligned CNTs rapidly and effectively (lack of voids) using off-the-shelf polymers. The wetting process not only preserves the alignment of the CNTs, but also allows the controlled manufacturing of nanocomposite test structures. Direct characterization of the mechanical properties of the nanocomposite structures is also presented in this work. The mechanical-reinforcement results support the feasibility of using these CNTarrays in large-scale hybrid advanced composite architectures reinforced with aligned CNTs. Such composites will also benefit from multifunctional property (e.g., electrical conductivity) enhancements owing to the aligned CNTs.