| Description |
Carbon nanotubes (CNTs) exhibit extraordinary mechanical properties and display a high surface to volume ratio, which makes them a good filler material for polymer based composite materials. Their mechanical properties are most effectively utilized by aligning the tube axis in the direction of the applied loading. Several methods exist to align CNTs, including wet spinning, dry spinning, mechanical stretching, magnetic field alignment, and plasma enhanced chemical vapor deposition. However, the scalability of these methods is limited and, thus, they are only suited to align small amounts of CNTs. This work introduces a novel technique, based on bulk acoustic waves (BAWs), to align large amounts of CNTs quasi-instantaneously. This technique is employed to fabricate macroscale composite materials with aligned CNTs as filler material. CNTs are first dispersed in the liquid state of a thermoset resin and introduced into a reservoir where the alignment is performed by BAWs. The cross-linking of the resin fixates the aligned CNTs in the resin matrix and produces a composite material with aligned CNTs. Composite material specimens were produced using this technique with CNT loading rates up to 2 weight percent (wt%). The mechanical properties of these composites were evaluated experimentally and compared against specimens consisting of both randomly oriented CNTs and pure resin matrix material. Composite material specimens with aligned CNTs (0.15 wt %) displayed a 44% and 51% increase in elastic iv modulus compared to composite material specimens with randomly oriented CNTs and pure resin material specimens, respectively. However, due to insufficient dispersion of CNTs in the resin matrix a significant increase in elastic modulus and ultimate tensile strength with increasing CNT loading rate was not observed. |
