Anisotropic Thermal Conductivity in Pellet-Based 3D-Printed Polymer Structures for Advanced Heat Management in Electrical Devices
Abstract
1. Introduction
2. Materials and Methods
2.1. Polymer Pellets
2.2. Manufacturing of Printed Structures
2.3. Observation of Printed Structures
2.4. Thermal Conductivity Measurement
2.5. Dielectric Measurement
3. Results and Discussion
3.1. Microscopic Analysis of Printed Structures
3.2. Results of Thermal Conductivity
3.3. Dielectric Properties
- Filler orientation effect: the platelet-shaped mineral fillers, when aligned parallel to the electric field direction (sample X), create more extensive interfacial regions perpendicular to the field, enhancing interfacial polarization. The flake-like morphology observed in the microscopic analysis (see Figure 2) supports this interpretation. Studies on mica and clay-filled polymer composites have reported similar orientation-dependent dielectric behavior, with anisotropy ratios ranging from 1.1 to 1.8, depending on the filler aspect ratio and loading [38,39];
- Matrix microstructure effect: the FGF printing process may induce preferential orientation of PA6 crystallites and chain alignment along the extrusion direction. Previous studies on FDM-printed PA6 composites have demonstrated that processing-induced molecular orientation can significantly affect dielectric properties, with aligned chains exhibiting higher polarizability along the orientation axis [36].
4. Conclusions
- Filler orientation dominates thermal transport—the parallel alignment of mineral fillers yields thermal conductivity of 4.09 W/m·K compared to 1.21 W/m·K for perpendicular orientation, representing a 238% enhancement. This demonstrates that manufacturing process control is critical for optimizing thermal performance;
- Strong thermal anisotropy was achieved—the anisotropy ratio of 3.4 is one of the highest reported for electrically insulating 3D-printed thermoplastic composites. This directional heat transfer capability enables targeted thermal management in confined spaces;
- A significant reduction in thermal resistance was obtained—parallel-oriented samples exhibited 70% lower thermal resistance (24.8 × 10−4 m2·K/W) compared to samples with a perpendicular orientation (82.6 × 10−4 m2·K/W). For a typical heat flux of 10 W/cm2, this translates to a 58 °C reduction in temperature rise, directly improving device reliability;
- Electrical insulation was maintained—despite the enhanced thermal conductivity, the material preserved excellent dielectric properties with low dielectric loss (tan δ < 0.05 at 1 kHz) and high surface resistivity (4 × 1014 Ω), meeting requirements for electrical insulation in medium-voltage applications;
- Industrial scalability is possible—the pellet-based FGF process enables direct use of industrial-grade polymer composites without intermediate filament production, reducing cost and expanding material options for thermal management applications in electrical devices.
5. Patents
Author Contributions
Funding
Institutional Review Board Statement
Data Availability Statement
Acknowledgments
Conflicts of Interest
References
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| Properties | Description or Value | Unit |
|---|---|---|
| Density | 1.68 | g/cm3 |
| HDT, 0.45 MPa | 203 | °C |
| Flexural strength | 105 | MPa |
| Tensile strength | 75 | MPa |
| Tensile strain | 1.1 | % |
| Impact strength | 9 | kJ/m2 |
| Thermal conductivity through-plane | 1.2 | W/m·K |
| Thermal conductivity in-plane | 5.5 | W/m·K |
| Surface resistivity | 4·× 1014 | Ω |
| Dielectric strength | 7.2 | kV/mm |
| Flame class rating, UL 94 | V-0 |
| Settings and Conditions | Value |
|---|---|
| Upper-plate temperature (°C) | 30 |
| Lower-plate temperature (°C) | 10 |
| Ambient temperature (°C) | 20 |
| Measurement type | Through thickness |
| Expected accuracy | Within 5% |
| Sample Type | Sample Thickness 1 (mm) | Thermal Conductivity () | Thermal Resistance () |
|---|---|---|---|
| X1 | 10.12 | 4.12 ± 0.11 | 24.6 ± 0.6 |
| X2 2 | 10.15 | 4.06 ± 0.04 | 25.0 ± 0.2 |
| Y1 2 | 9.85 | 1.20 ± 0.01 | 82.4 ± 0.9 |
| Y2 | 10.16 | 1.23 ± 0.02 | 82.7 ± 1.3 |
| Z | 10.15 | 2.11 ± 0.03 | 48.1 ± 0.7 |
| Polymer Matrix | Filler Type | TC Max | TC Min | TC Anisotropy Ratio | Printing Method | Electrical Properties | Reference |
|---|---|---|---|---|---|---|---|
| PA6 | Mineral (BN-type) | 4.09 | 1.21 | 3.4 | FGF | Insulating | This work |
| Flexible resin | BN platelets (20 wt.%) | 0.73 | 0.51 | 1.4 | VPP | Insulating | [24] |
| PLA | Carbon fiber | 0.20 | 0.16 | 1.2 | FFF | Conductive | [25] |
| Polymer Matrix | Filler Type | Dielectric Constant @ 1 kHz | Dissipation Factor @ 1 kHz | Manufacturing Method | Reference |
|---|---|---|---|---|---|
| PA6 | Mineral (BN-type) | 6 ÷ 8 | <0.05 | FGF | This work |
| Flexible resin | BN platelets (20 wt.%) | 8 | 0.2 | VPP | [24] |
| Epoxy resin | BN platelets (30 wt.%) | 4.5 | <0.02 | Vacuum casting | [14] |
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Rzepecki, M.; Rybak, A. Anisotropic Thermal Conductivity in Pellet-Based 3D-Printed Polymer Structures for Advanced Heat Management in Electrical Devices. Polymers 2026, 18, 93. https://doi.org/10.3390/polym18010093
Rzepecki M, Rybak A. Anisotropic Thermal Conductivity in Pellet-Based 3D-Printed Polymer Structures for Advanced Heat Management in Electrical Devices. Polymers. 2026; 18(1):93. https://doi.org/10.3390/polym18010093
Chicago/Turabian StyleRzepecki, Michal, and Andrzej Rybak. 2026. "Anisotropic Thermal Conductivity in Pellet-Based 3D-Printed Polymer Structures for Advanced Heat Management in Electrical Devices" Polymers 18, no. 1: 93. https://doi.org/10.3390/polym18010093
APA StyleRzepecki, M., & Rybak, A. (2026). Anisotropic Thermal Conductivity in Pellet-Based 3D-Printed Polymer Structures for Advanced Heat Management in Electrical Devices. Polymers, 18(1), 93. https://doi.org/10.3390/polym18010093

