Title: Thermally Conductive Melt-Processable Polyimide Hbn Micro-Composites for High Temperature Electrical Insulation Applications

Authors: Witold K. Fuchs, Robin Weaver, Gabriel Antomattei-Alejandro, Tiffany S. Williams, Baochau N. Nguyen

DOI: 10.33599/nasampe/s.24.0127

Abstract: "Thermoplastic polymers exhibit excellent dielectric properties and manufacturing robustness. These properties mark thermoplastics as competitive material candidates for electrical insulation applications. However, the high-temperature performance of most thermoplastics is insufficient to meet the electrical wiring requirements for next-generation air and space transportation engineering designs, with continuous operation temperature requirements of up to 200 °C among other design requirements. Furthermore, the low thermal conductivity (κ) of polymers as a material class leads to heat trapping within wires which can amplify thermal stresses. As a result, there is a need to investigate candidate thermoplastic systems for their high temperature, dielectric, and κ performance. The goal of this work was to develop and characterize high operating temperature, melt processable, and thermally conductive thermoplastic electrical insulation materials systems to improve thermal management in high power density electric motors. Thermoplastic polyimide (TP PI) composites with up to 25 wt% micro-hBN were compounded and injection molded. The resultant composites exhibited good thermal stability with Tgs of 276 °C, mechanical robustness, and improvements in thermal conductivity by up to 70% while maintaining dielectric performance. A further post-processing step was demonstrated which again increased thermal conductivity to a total 110% improvement."

References: [1] [Haque, SK, M., Ardila-Rey, J., et al., Application and Suitability of Polymeric Materials as Insulators in Electrical Equipment. MDPI, 2021, DOI: https://doi.org/10.3390/en14102758] [2] [Do, N., Imenes, K., et al., Thermal conductivity and mechanical properties of polymer composites with [hBN] – a comparison of three processing methods… MDPI, 2023, DOI: https://doi.org/10.3390/polym15061552] [3] Huang, C., Qian, X., et al., Thermal conductivity of polymer and polymer nanocomposites. Materials Science and Engineering Reports, Vol. 132, 2018, DOI: https://doi.org/10.1016/j.mser.2018.06.002] [4] Zhang, X., Zhang, J., et al. Simple and consecutive melt extrusion method to fabricate thermally conductive composites with highly oriented boron nitrides. ACS Applied Materials & Interfaces, 2017, DOI: https://10.1021/acsami.7b05866] [5] Kim, K., Kim, M., et al. Chemically modified boron nitride-epoxy terminated dimethylsiloxane composite for improving the thermal conductivity. Ceramic Interfaces, 2014, DOI: https://doi.org10.1016/j.ceramint.2013.07.117] [6] Harada, M., Hamaura, N., Thermal conductivity of liquid crystalline epoxy/BN filler composites having ordered network structure. Composites, Part B. 2013, DOI: https://doi.org/10.1016/j.compositesb.2013.06.031] [7] Fu, Y. X., He, Z. X., Thermal conductivity enhancement with different fillers for epoxy resin adhesives. Appl. Therm. Eng., 2014, DOI: https://doi.org/10.1016/j.applthermaleng.2014.02.044] [8] [Xiao, M., Du, X. B., Review of high thermal conductivity polymer dielectrics for electrical insulation. High Voltage, Vol. 1, Iss. 1, 2016, DOI: 10.1049/hve.2016.0008] [9] [Huang, X., Izuka, T., et al, A review of dielectric polymer composites with high thermal conductivity, IEEE Electrical Insulation Magazine, vol. 27, no. 4, 2011, DOI: 10.1109/MEI.2011.5954064] [10] [Williams, T., Nguyen, B., et al., Polyphenylsulfone-hBN composite insulation, IEEE 3rd International Conference on Dielectrics, 2020, DOI: 10.1109/ICD46958.2020.9341910] [11] [Bai, X., Zhang, C., et al., Recent progress in thermally conductive polymer/boron nitride composites by constructing three-dimensional networks, Composites Communications, 2021, DOI: https://doi.org/10.1016/j.coco.2021.100650] [12] [Williams, T., Nguyen, B., et al, Fabrication of extruded polyphenylsulfone – boron nitride composite tapes, SAMPE 2021] [13] [Polartherm* boron nitride powder: PT 140, PT 160, and PT 180. [Online], https://www.momentive.com/docs/default-source/productdocuments/boron-nitride-powder-polartherm-and-polartherm-ptx-additives/polartherm-bn-powder-grades-pt140-pt160-pt180.pdf?sfvrsn=c8a89c21_18 . Accessed December 7, 2020] [14] [ASTM D149-09, Standard Test Method for Dielectric Breakdown Voltage and Dielectric Strength of Solid Electrical Insulating Materials at Commercial Power Frequencies, ASTM International, 04/2023, https://www.astm.org/d0149-09.html] [15] [ANSI/UL 746B, Standard for Safety for Polymeric Materials – Long Term Property Evaluations, Underwriters Laboratories Inc., 10/2022, https://www.ul.com/resources/standards-evaluating-plastic-products] [16] [Tan, D., The search for enhanced dielectric strength of polymer-based dielectrics: A focused review on polymer nanocomposites, Journal of Applied Polymer Science, 2020, DOI 10.1002/app.49379] [17] [Yu, J., Jiang, P., Polymer/boron nitride nanosheet composite with high thermal conductivity and sufficient dielectric strength, Polymers for Advanced Technologies, 2015, DOI: https://doi.org/10.1002/pat.3481] [18] [Lokanathan, M., et al., Review of Nanocomposite Dielectric Materials with High Thermal Conductivity, Proceedings of the IEEE, 2021, DOI: 10.1109/JPROC.2021.3085836]

Conference: SAMPE 2024

Publication Date: 2024/05/20

SKU: TP24-0000000127

Pages: 11

Price: $22.00