Date

2022-8

Author

Görür, Mustafa Caner

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The use of electronic devices in all sectors is inevitable and any improvement in energy savings has great effects on a global basis. The thermal management of these devices is the most important factor in energy savings because as these devices get smaller, the amount of heat they emit increases, and this excess heat considerably shortens their lifespan. Therefore, current research has focused on the release of heat to the environment rather than trapping it in devices. Hexagonal boron nitride (h-BN) nanosheets, on which many studies have been carried out in recent years, draw attention with their electrical resistivity and high thermal conductivity. h-BN is known as “white graphene” because of the similarity of its lattice structure and thermal properties with graphene. However, unlike graphene, h-BN nanosheets are electrically resistive that makes them promising candidates for the thermal management of electronic devices. In addition, reducing the number of layers of h-BN expands the surface area and prevents phonon scattering during heat conduction, thereby significantly increasing the thermal conductivity value.Additive manufacturing (AM) is a fast and economically feasible prototype production method that allows fabrication of complex structures. In addition, AM considers many parameters such as infill percentage of material use, the angle of printing, printing speed and pattern, and height of each layer that are used to optimize the production. In this thesis, h-BN nanosheets are used as filler materials for the production of nanocomposites with polylactic acid (PLA) matrix. For this purpose, h-BN nanosheet/PLA nanocomposite filaments suitable for 3D printing were prepared, which were then used to 3D print heat dissipating devices for the thermal management of electronic devices. In this regard, h-BN was exfoliated with both ball-milling and shear exfoliation methods. Few-layered h-BN nanosheets stable in water for more than one month were obtained in both methods. Shear exfoliation was chosen as the main production method since it allowed production of large amounts of few layered (<10 layers) of h-BN nanosheets. Afterwards, h-BN/PLA filaments were used to print a heat sink and LED bulb holder for thermal management applications. In the first application, heat sinks were heated from their lower surfaces. The temperature of the upper surface of the 3D printed h-BN/PLA heat sink was found 6.3 °C higher than 3D printed bare PLA and just 1.4 °C lower than that of the commercial aluminum (Al) heat sink. The heat dissipation rate of PLA was found to increase by 320% by adding 40 vol. % h-BN. In the second application, printed LED bulb holders were assembled into a LED bulb and LED temperatures were monitored. The lowest temperature detected on the LED chips was 120.8 °C for the 3D printed h-BN/PLA sample. The temperature of the commercial LED bulb was detected as 122.1 °C and 3D printed bare PLA sample showed the highest temperature of 136.4 °C. This experiment proved that h-BN/PLA nanocomposites can be used to extend the lifetime of LED bulbs.

Subject Keywords

3D printing, Hexagonal boron nitride nanosheets, Exfoliation, PLA matrix nanocomposites, Thermal management devices

URI

https://hdl.handle.net/11511/99598

Collections

Graduate School of Natural and Applied Sciences, Thesis