Tailoring Functional And Sensing Properties Of Polymer-Ceramic Composites Via 3d Printing

Abstract

Section 1.1. Abstract This chapter investigates the use of direct ink write (DIW) additive manufacturing to control grain orientation in non-toxic barium titanate (BTO) ceramics by blending spherical and platelet-shaped particles in the ink. A series of inks containing 0–40 wt.% BTO platelets were formulated with poly(vinyl alcohol), polyethylene glycol, poly(acrylic acid-co-maleic acid), and ammonium hydroxide to ensure printability and homogeneous dispersion. Cylindrical specimens (20 mm × 3 mm) were printed using a Hyrel 30M DIW system and subjected to de-binding (650 °C, 2 h) followed by a two-step sintering schedule (T₁: 1200–1350 °C; T₂: 700–850 °C; 24 h dwell). Relative density peaked at 85.9 % for 0 wt.% platelets (1300 °C/800 °C) and decreased with increasing platelet content due to inhibited grain-boundary diffusion. SEM and XRD analyses confirmed platelet alignment parallel to the build plate, with Lotgering factors (F₂₀₀) rising from 0.00 (0 wt.%) to 0.63 (40 wt.%). This texturization produced a 29.6 % enhancement in dielectric constant compared to randomly oriented ceramics. The results demonstrate that DIW-induced shear alignment coupled with optimized thermal processing can tailor microstructure and functional performance of BTO ceramics for sensor and energy-storage applications. Section 2.1. Abstract This chapter presents the development of multifunctional lattice structures fabricated from a novel PEEK–carbon fiber (CF)/carbon nanotube (CNT) composite filament for fused filament fabrication (FFF). An optimized melt-blend extrusion process produced filaments with 11.6 wt.% CF and 12 wt.% CNT, yielding uniform dispersion and robust interfacial bonding. Two lattice geometries—truncated octahedron and re-entrant auxetic—were selected to exploit plateau stress regions (5–15 % strain) for decoupling piezoresistive and thermoresistive responses. Printed specimens exhibited surface roughness as low as ~20 µm Ra, compressive strengths up to 60 MPa, and electrical conductivities reaching 0.067 S/m. Cyclic loading under controlled temperatures (25–100 °C) confirmed stable resistance during plateau stress and a positive temperature coefficient of resistance with \u3c 0.3 % variation, achieving 99.7 % repeatability. These results demonstrate that lattice architecture, combined with tailored composite formulation, enables selective force and temperature sensing in a single-material system. Section 3.1. Abstract This chapter introduces Hybrid PIZCAL, a multi-material lattice architecture enabling programmable directional piezoelectric sensing via fused filament fabrication (FFF). Using an ABS–BaTiO₃ composite filament with 20 vol.% ceramic loading co-printed alongside pure PLA, we create geometrically anisotropic lattices that concentrate mechanical strain along the Z-axis while passivating the X–Y planes. Thermal poling (3 kV/mm at 85 °C) aligns dipoles in the active regions, yielding a Z-axis voltage-per-mass output of 13.7 mV/g—293 % higher than a monolithic piezoelectric cube—while suppressing transverse responses by \u3e20 %. Finite-element simulations confirm compliance contrasts exceeding 5× between axes, and SEM micrographs demonstrate homogeneous BaTiO₃ dispersion within the ABS matrix. The Hybrid PIZCAL thus combines topological control with material zoning to deliver high-fidelity, single-axis sensing in a single-step AM process, paving the way for advanced wearable, robotic, and structural-health-monitoring applications