Thermomechanical Multifunctionality in 3D-Printed Polystyrene-Boron Nitride Nanotubes (BNNT) Composites

Thermally Conductive and Electrically Insulating Polymer-Based Composites Heat Sinks Fabricated by Fusion Deposition Modeling

This study explores the potential of novel boron nitride (BN) microplatelet composites with combined thermal conduction and electrical insulation properties. These composites are manufactured through Fusion Deposition Modeling (FDM), and their application for thermal management in electronic devices is demonstrated. The primary focus of this work is, therefore, the investigation of the thermoplastic composite properties to show the 3D printing of lightweight polymeric heat sinks with remarkable thermal performance. By comparing various microfillers, including BN and MgO particles, their effects on material properties and alignment within the polymer matrix during filament fabrication and FDM processing are analyzed. The characterization includes the evaluation of morphology, thermal conductivity, and mechanical and electrical properties. Particularly, a composite with 32 wt% of BN microplatelets shows an in-plane thermal conductivity of 1.97 W m-1 K-1, offering electrical insulation and excellent printability. To assess practical applications, lightweight pin fin heat sinks using these composites are designed and 3D printed. Their thermal performance is evaluated via thermography under different heating conditions. The findings are very promising for an efficient and cost-effective fabrication of thermal devices, which can be obtained through extrusion-based Additive Manufacturing (AM), such as FDM, and exploited as enhanced thermal management solutions in electronic devices.

Thermal and Electrical Properties of Additively Manufactured Polymer-Boron Nitride Composite

The efficiency of electronic microchip-based devices increases with advancements in technology, while their size decreases. This miniaturization leads to significant overheating of various electronic components, such as power transistors, processors, and power diodes, leading to a reduction in their lifespan and reliability. To address this issue, researchers are exploring the use of materials that offer efficient heat dissipation. One promising material is a polymer-boron nitride composite. This paper focuses on 3D printing using digital light processing of a model of a composite radiator with different boron nitride fillings. The measured absolute values of the thermal conductivity of such a composite in the temperature range of 3-300 K strongly depend on the concentration of boron nitride. Filling the photopolymer with boron nitride leads to a change in the behavior of the volt-current curves, which may be associated with the occurrence of percolation currents during the deposition of boron nitride. The ab initio calculations show the behavior and spatial orientation of BN flakes under the influence of an external electric field at the atomic level. These results demonstrate the potential use of photopolymer-based composite materials filled with boron nitride, which are manufactured using additive techniques, in modern electronics.

Combined Additive and Laser-Induced Processing of Functional Structures for Monitoring under Deformation

This research introduces a readily available and non-chemical combinatorial production approach, known as the laser-induced writing process, to achieve laser-processed conductive graphene traces. The laser-induced graphene (LIG) structure and properties can be improved by adjusting the laser conditions and printing parameters. This method demonstrates the ability of laser-induced graphene (LIG) to overcome the electrothermal issues encountered in electronic devices. To additively process the PEI structures and the laser-induced surface, a high-precision laser nScrypt printer with different power, speed, and printing parameters was used. Raman spectroscopy and scanning electron microscopy analysis revealed similar results for laser-induced graphene morphology and structural chemistry. Significantly, the 3.2 W laser-induced graphene crystalline size (La; 159 nm) is higher than the higher power (4 W; 29 nm) formation due to the surface temperature and oxidation. Under four-point probe electrical property measurements, at a laser power of 3.8 W, the resistivity of the co-processed structure was three orders of magnitude larger. The LIG structure and property improvement are possible by varying the laser conditions and the printing parameters. The lowest gauge factor (GF) found was 17 at 0.5% strain, and the highest GF found was 141.36 at 5%.

Progress of Polymer-Based Thermally Conductive Materials by Fused Filament Fabrication: A Comprehensive Review

With the miniaturization and integration of electronic products, the heat dissipation efficiency of electronic equipment needs to be further improved. Notably, polymer materials are a choice for electronic equipment matrices because of their advantages of low cost and wide application availability. However, the thermal conductivity of polymers is insufficient to meet heat dissipation requirements, and their improvements remain challenging. For decades, as an efficient manufacturing technology, additive manufacturing has gradually attracted public attention, and researchers have also used this technology to produce new thermally conductive polymer materials. Here, we review the recent research progress of different 3D printing technologies in heat conduction and the thermal conduction mechanism of polymer matrix composites. Based on the classification of fillers, the research progress of thermally conductive materials prepared by fused filament fabrication (FFF) is discussed. It analyzes the internal relationship between FFF process parameters and the thermal conductivity of polymer matrix composites. Finally, this study summarizes the application and future development direction of thermally conductive composites by FFF.

Highly electromagnetic transparent ceramic composite made of boron nitride nanotubes and silicon oxynitride via perhydropolysilazane infiltration method

With the rapid development of electromagnetic (EM) wave circuit devices, high-performance wave-transparent materials with various functions have attracted great attention. Ceramic material is a promising candidate to be applied in harsh environments because of its chemical and corrosion resistance. In this work, a polymer-derived route was adopted to synthesize ceramic composite at room temperature. The composite is made of perhydropolysilazane-derived SiON ceramic and reinforced with boron nitride nanotubes (BNNTs) sheets. With the addition of SiON ceramic materials, the resultant sample showed an excellent hydrophobicity with a contact angle of 135–146.9°. More importantly, superior thermal stability at 1600 °C in the oxygen-containing atmosphere was observed for the fabricated SiON/BNNTs sample, without any shape change. The electromagnetic transparency of the SiON/BNNTs was studied through the waveguide method. The prepared SiON/BNNTs sample has an average real permittivity between 1.52 and 1.55 and an average loss tangent value in the range of 0.0074–0.0266, at the frequency range of 26.5–40 GHz. The effect of thickness on the wave transparency of SiON/BNNTs samples is also discussed. To summarize the aforementioned superior characterization and measurement results, the presented SiON/BNNTs material system has a great potential to be used as EM transparent materials in harsh conditions.

Boron nitride nanotubes enhance mechanical properties of fibers from nanotube/polyvinyl alcohol dispersions

Effectively translating the promising properties of boron nitride nanotubes (BNNTs) into macroscopic assemblies has vast potential for applications, such as thermal management materials and protective fabrics against hazardous environment. We spun fibers from aqueous dispersions of BNNTs in polyvinyl alcohol (PVA) solutions by a wet spinning method. Our results demonstrate that BNNTs/PVA fibers exhibit enhanced mechanical properties, which are affected by the nanotube and PVA concentrations, and the coagulation solvent utilized. Compared to the neat PVA fibers, we obtained roughly 4.3-, 12.7-, and 1.5-fold increases in the tensile strength, Young's modulus, and toughness, respectively, for the highest performing BNNTs/PVA fibers produced from dispersions containing as low as 0.1 mass% of nanotube concentration. Among the coagulation solvents tested, we found that solvents with higher polarity such as methanol and ethanol generally produced fibers with improved mechanical properties, where the fiber toughness shows a strong correlation with solvent polarity. These findings provide insights into assembling BNNTs-based fibers with improved mechanical properties for developing unique applications.