Fabrication and Characterization of Ultrahigh‐Volume‐ Fraction Aligned Carbon Nanotube–Polymer Composites

Abstract

Aligned CNT nanocomposites with variable volume fraction, up to 20%, are demonstrated. Biaxial mechanical densification of aligned CNT forests, followed by capillarity-driven wetting using unmodified aerospace-grade polymers, creates centimeter-scale specimens. Characterizations confirm CNT alignment and dispersion in the thermosets, providing a useful platform for controlled nanoscale interaction and nanocomposite property studies that emphasize anisotropy.

Morphology and processing of aligned carbon nanotube carbon matrix nanocomposites

“…Aligned CNT arrays were grown via a previously described thermal catalytic chemical vapor deposition process using ethylene as the carbon source [15][16][17][18] . The forests were grown on 1 cm × 1 cm Si substrates to form CNT arrays that are ∼ 1 mm tall, have an average inter-CNT spacing of ∼ 80 nm 40 , and volume fractions of ∼ 1% CNTs 41 .…”

“…3 if necessary for nanofiber arrays with lower φ o values (volume fractions > 1%), such as densified CNT arrays 15,16,18,24,40 . Because Eq.…”

“…These materials can be produced through the heat treatment (pyrolysis) of aligned nanofiber polymer matrix nanocomposite (A-PNC) precursors, which are analogous to the APNCs reported elsewhere [15][16][17][18][19][20][21][22][23][24] . Such processing follows the typical synthesis routes of polymer derived ceramics [25][26][27][28] , but relies on capillary [15][16][17][18][19][20][21] or vacuum [21][22][23][24] assisted wetting of the aligned nanofibers rather than surfactant or functionalization assisted mixing. In order to manufacture aligned nanofiber carbon matrix nanocomposites (A-CMNCs) with tailored properties, the porosity of the matrix, which strongly influences its material properties, must be controlled.…”

“…Previous studies on the morphology of the CNT arrays, known as forests, indicate that the average inter-CNT spacing in the as-grown (∼ 1 vol. %) CNT forests is ∼ 80 nm 18,40 , meaning that the fabrication of low porosity A-PNCs is possible. However, once the polymer precursors are heat treated, additional porosity forms, and modeling indicates that its reduction to a value similar to that of carbon fiber reinforced carbon matrix composites ( 20%) 28 may not be possible using wet infusion in A-CMNCs.…”

Ultrahigh Carbon Nanotube Volume Fraction Effects on Micromechanical Quasi-Static & Dynamic Properties of Poly(Urethane-Urea) Filled Nanocomposites

“…This interphase region has been shown to be affected by CNT proximity [3][4][5][6][7][8][9]. Furthermore, packing and confinement effects which arise from even moderate CNT volume fractions (Vf's) give rise to additional nanostructure [10]. To investigate the phenomena governing this interphase, a model system of vertically aligned CNT forests has been used, which allows for excellent control of CNT Vf and dispersion, while eliminating any potentially confounding effects of more complex hierarchical composites.…”