A Novel Multi-Material Additive Manufacturing Technique for Fabricating Laminated Polymer Nanocomposite Structures

Abstract

The objective of this research is to develop a novel, multi-material additive manufacturing technique for fabricating laminated polymer nancomposite structures that have characteristic length-scales in the tens of millimeters range. The 3D printing technology presented in this paper combines the conventional inkjet-based printing of ultraviolet (UV) curable polymers with the deposition of either aligned or random nano-scale fiber mats, in between each printed layer. The fibers are first generated using an electrospinning process that produces the roll of fibers. These fibers are then transferred to the part being manufactured using a stamping operation. The process has been proven to manufacture multi-material laminated nanocomposites having different 3D geometries. The dimensional accuracy of the parts is seen to be a function of the interaction between the different UV-curable polymer inks. In general, the addition of the nanofibers in the form of laminates is seen to improve the mechanical properties of the material, with the Young’s modulus and the ultimate breaking stress showing the most improvement. The pinning and deflection of micro-cracks by the nano-scale fiber mats has been identified to be the underlying mechanism responsible for these improved mechanical properties. The thermogravimetric analysis reveals that these improvements in the mechanical properties are obtained without drastically altering the thermal degradation pattern of the base polymer.

Droplet spreading characteristics observed during 3D printing of aligned fiber-reinforced soft composites

“…The 3D printing of FrSCs first includes the manufacture of the fiber mats using either a near-field or far-field electrospinning-based direct-write process [9,19]. These fiber mats are then transferred to a five-axis inkjet-based 3D printing platform.…”

“…Ink 3 is analogous to Sartomer SR531, which was used to create FrSCs by Spackman et. al [9]. Ink 4 is similar in viscosity to Stratasys TangoPlus FLX930, the ink most commonly used to 3D print FrSCs.…”

“…Nylon 6 was chosen as the material for the fiber mats, given its prior demonstrated use in 3D printed FrSCs [9]. Three different aligned Nylon 6 fiber mats of varying effective area coverage (EAC) values were produced using the near-field direct-write setup described in Spackman et al [9]. Figures 4a-c depict the characteristic structure of these aligned mats.…”

“…Current 3D printing processes such as fused deposition modeling [6], stereolithography [7], and inkjet-based deposition of UV curable polymers [8] are not capable of printing FrSCs. Recently, Spackman et al [9] developed a novel hybrid 3D printing process to manufacture FrSCs. This process combines the conventional inkjet-based 3D printing technique with the directed deposition of micro/sub-micron fibrous structures manufactured using electrospinning.…”

“…There have also been studies concerning micro-scale droplets deposited on wrinkled or grooved substrates [18]. However, the substrate scenarios in these studies are not comparable to the multi-material, fibrous surfaces encountered during the 3D printing of FrSCs [9].…”