Laminated object manufacturing of CNT buckypapers towards solid 3D structures

Laminated object manufacturing (LOM) is rarely applied in the fabrication of functional structures, as most additive manufacturing methods incorporate nanomaterials within polymer matrices. Carbon nanotube (CNT) buckypapers provide a pathway to translate the exceptional nanoscale properties of CNTs into free-standing microscale sheets. In this study, CNT buckypapers fabricated by vacuum filtration were used as the primary feedstock for sheet lamination. The resulting 3D laminated structures produced by the additive lamination method were evaluated for mechanical, electrical, and thermal behavior to elucidate structure–property relationships associated with layer stacking. Manually stacked CNT structures exhibited significantly higher tensile strength (∼12-14 MPa) than LOM-printed structures (∼8.5 MPa), while LOM-printed specimens showed considerably higher Young's modulus (up to ∼830 MPa). In transport properties, electrical conductivity decreased from ∼75 S/cm for individual buckypaper to 46.29 S/cm and 43.43 S/cm for LOM-printed 3L and 5L structures, respectively. Manually stacked equivalents yielded lower values of 36.69 S/cm (3L) and 27.37 S/cm (5L). Thermal conductivity decreased from 16.73 W/m·K for individual buckypaper to 10.83 W/m·K and 9.72 W/m·K for LOM-printed 3L and 5L structures. Electromechanical testing further showed an increase in electrical conductivity under compressive loading. These results establish LOM as a viable additive manufacturing route for fabricating functional CNT structures.