Mechanical, electrical, and piezoresistivity behaviors of additively manufactured acrylonitrile butadiene styrene/carbon nanotube nanocomposites

Tensile, fracture, electrical, and piezoresistivity behaviors of additively manufactured acrylonitrile butadiene styrene (ABS)/carbon nanotube (CNT) nanocomposites were investigated. Filaments with CNT contents up to 10 wt% were fabricated using a twin-screw extruder and 3D printed through fused filament fabrication (FFF). The printed ABS samples showed similar or better strength, stiffness, and strain-at-break values, compared to those of compression-molded counterparts. The strength and stiffness of the printed ABS were significantly enhanced by introducing CNT, with an optimum content of ∼3.0–5.0 wt%. The ductile fracture behavior and high fracture resistance (K_Ic = 2.2–2.4 MPa m^1/2 and G_Q = 3 kJ m⁻²) of ABS was maintained in the nanocomposites with a maximum CNT content of 3.0 wt%, beyond which it decreased significantly. The printed samples' conductivity was at least one order of magnitude lower than that of the compression-molded ones. Moreover, the in-layer conductivity was about two orders of magnitudes higher than the through-layer one, introducing a noticeable anisotropy at lower CNT contents. The piezoresistivity tests revealed a relatively linear resistance–strain relationship for the elastic region. A sudden change in the resistance was also detected at the onset of plastic deformation. These variations in the mechanical and electrical behaviors were explained in terms of the CNT agglomerates, CNT alignment, interlayer bond quality, and the inter-raster voids. (paper)