Rheological Issues in Carbon-Based Inks for Additive Manufacturing

Abstract

As the industry and commercial market move towards the optimization of printing and additive manufacturing, it becomes important to understand how to obtain the most from the materials while maintaining the ability to print complex geometries effectively. Combining such a manufacturing method with advanced carbon materials, such as Graphene, Carbon Nanotubes, and Carbon fibers, with their mechanical and conductive properties, delivers a cutting-edge combination of low-cost conductive products. Through the process of printing the effectiveness of these properties decreases. Thorough optimization is required to determine the idealized ink functional and flow properties to ensure maximum printability and functionalities offered by carbon nanoforms. The optimization of these properties then is limited by the printability. By determining the physical properties of printability and flow properties of the inks, calculated compromises can be made for the ink design. In this review we have discussed the connection between the rheology of carbon-based inks and the methodologies for maintaining the maximum pristine carbon material properties.

Direct Ink Writing of Wearable Thermoresponsive Supercapacitors with rGO/CNT Composite Electrodes

“…The DIW printing resolution of carbon‐based materials in recently reported literature is in the range of 0.5–2.0 mm . To maintain the maximum pristine carbon material properties for high energy performance, many carbon material based inks used in the DIW process are free of binders, which results in poor dispersion of carbon‐based materials in a watery mixture . The rheological issue of those low‐viscosity inks limits the printing resolution in the DIW process.…”

“…It should be noted that the flow rate is dependent on the ink viscosity . Therefore, to address the shrinkage problem during PDMS printing, a possible solution is to adjust the printing velocity over time, as illustrated in Figure b.…”

Nanomaterial Patterning in 3D Printing

“…In general, the rheological properties of the nanocomposite ink in extrusion 3D printing methods is tuned such that it can be extruded from the nozzle, without challenges such as clogging due to nanoparticle aggregation 166,167. In high viscosity DIW, inks are often formulated to have shear thinning behavior, which reduces the apparent viscosity with increasing shear rate to promote extrusion through the nozzle 167.…”

Rheological Issues of Phase Change Materials Obtained by the Complex Coacervation of Butyl Stearate in Poly Methyl Methacrylate Membranes

“…If an interaction between the solution of a single polymer and the encapsulated substance is achieved, the process is simple coacervation, and if the coacervation is accomplished by an interaction between two polymers, it is called compound or complex coacervation [21][22][23][24]. Currently, the coacervation process of macromolecular compounds is considered the process by which a biphasic system is formed by stratification [25][26][27].…”