Compounding a High-Permittivity Thermoplastic Material and Its Applicability in Manufacturing of Microwave Photonic Crystals

Abstract

Additive Manufacturing (AM) techniques allow the production of complex geometries unattainable through other traditional technologies. This advantage lends itself well to rapidly iterating and improving upon the design of microwave photonic crystals, which are structures with intricate, repeating features. The issue tackled by this work involves compounding a high-permittivity material that can be used to produce 3D microwave photonic structures using polymer extrusion-based AM techniques. This material was acrylonitrile butadiene styrene (ABS)-based and used barium titanate (BaTiO3) ceramic as the high-permittivity component of the composite and involved the use of a surfactant and a plasticizer to facilitate processing. Initial small amounts of the material were compounded using an internal batch mixer and studied using polymer thermal analysis techniques, such as thermogravimetric analysis, rheometry, and differential scanning calorimetry to determine the proper processing conditions. The production of the material was then scaled up using a twin-screw extruder system, producing homogeneous pellets. Finally, the thermoplastic composite was used with a screw-based, material extrusion additive manufacturing technique to produce a slab for measuring the relative permittivity of the material, as well as a preliminary 3D photonic crystal. The real part of the permittivity was measured to be 12.85 (loss tangent = 0.046) in the range of 10 to 12 GHz, representing the highest permittivity ever demonstrated for a thermoplastic AM composite at microwave frequencies.

Polymeric composites in extrusion‐based additive manufacturing: a systematic review

“…Despite being non‐uniform and dependent on process parameters, the alignment achieved for a PLA/KNLN composite provided enhanced piezoelectric properties in comparison with the randomly‐oriented scenario 165 . Also exploring dielectric materials, Capote et al 130 combined barium titanate (BaTiO 3 ) and ABS for applications in microwave photonics, producing a prototype of a 3D photonic crystal 130 . Using the same polymeric matrix and a similar filler, Goulas et al 108 synthesized a composite filament of barium strontium titanium oxide (BaSrTiO 3 ) and ABS, adopting it to manufacture a prototype microstrip patch 5G antenna and a hemispherical dielectric lens.…”

“…Among the studies included in this review, all investigations regarding these alternative states were based on 3D printers with single‐screw extrusion mechanisms. Customized 88,144,157,158 and commercial equipment—such as Pollen Series P 3D printer 148,149 and Fused Form FF600+ 130 —were used. Except for the work by Dávila et al 157 —in which the authors adopted powder feedstock simply manually mixed in a mortar—all other mentioned papers were grounded on composite formulations that had been previously melt‐mixed and pelletized.…”

Three-Dimensional Printed Planar Polymer Photonic Topological Insulator Waveguides and Their Robustness to Lattice Defects

“…Toolpath generation was performed using the Simplify3D slicing engine (v4.1.2). The slicing parameters (Table S1) were selected iteratively to maximize the refractive index of the printed part while maintaining fidelity of the geometric features and constraining print times to ∼33 h. Shorter print times can in principle be achieved by using custom high-index thermoplastic materials and decreasing the infill percentage. , Common defects that arise due to the printing process included polymer drool between adjacent structures, unwanted z-height deposition that resulted in inconsistent height of the structure, voids in the areas where contiguous circular beads meet, and warpage. These issues were mitigated through manipulation of the slicing engine parameters, resulting in the structures used in this work.…”

Material Extrusion Additive Manufacturing with Polyethylene Vitrimers

“…Pellet-fed screw-assisted 3D printers are increasingly being used to bypass the need for filaments, reducing the associated cost of filament production, while also increasing the deposition rate and expanding the range of 3D-printing materials [ 31 ]. For example, modified 3D printers have enabled the use of recycled polymer flakes from polyethylene terephthalate (PET) water bottles [ 32 ], polymer composites that are too brittle to be spooled into filaments [ 33 ], and recycled selective laser sintering (SLS) powder [ 34 ].…”