The effect of water on the dielectric properties of polypropylene/aluminium nitride nanocomposites

Wang, Xinyu, Andritsch, Thomas and Chen, George (2019) The effect of water on the dielectric properties of polypropylene/aluminium nitride nanocomposites. 12th Universities High Voltage Network Colloquium, , Manchester, United Kingdom. 15 - 16 Jan 2019.

Abstract

A series of aluminium nitride/polypropylene nanocomposites were prepared. Nano aluminium nitride was surface functionalised by silane coupling agents with different hydrolysable groups and the effect of the surface chemistry and preconditioning (i.e., under different relative humidity) on their AC breakdown strength and the DC conductivity was investigated. The effect of water on the nanosilica-based nanocomposites have been studied by many researchers and the dramatically decreased AC breakdown strength and DC resistivity for wet samples were reported[1, 2]. By contrast, aluminium nitride filler with less hydrophilic sites, hydroxyl groups, was applied in this study. Furthermore, octyl silanes were adopted and the displacement of hydroxyl groups to short carbon chain on the particle surface is expected.

The preconditioning results show that the silane functionalisation can effectively reduce the amount of water absorbed during 15 days of immersion in deionized water. The dielectric properties show a high dependency on the sample preconditioning and water content. The DC conductivity of the non-treated aluminium nitride/polypropylene nanocomposites is 2 orders of magnitude higher than the octyl functionalised silane. Similar behaviour was observed on the AC breakdown data. However, the difference between systems treated with silane coupling agent with different hydrolysable groups cannot be seen from the weight monitoring and dielectric properties mentioned above. Although the dielectric results in [3] show the different hydrolysable groups might bring different bonding structure between nanoparticle and silane coupling agents, the interaction with water seems to have less dependency on it.
In this study, It can be concluded that the nanoparticle surface chemistry is very important in determining the macroscopic properties, especially in a humid environment. The surface functionalisation by silane coupling agent can effectively minimise the hydrophobicity of nanocomposites.

[1] D Qiang, Y Wang, G Chen, and T. Andritsch, "Influence of Water Absorption on Space Charge Behavior of Epoxy Nanocomposites," 2016.
[2] I. Hosier, M. Praeger, A. Holt, A. Vaughan, and S. Swingler, "On the effect of functionalizer chain length and water content in polyethylene/silica nanocomposites: Part I—Dielectric properties and breakdown strength," IEEE Transactions on Dielectrics and Electrical Insulation, vol. 24, no. 3, pp. 1698-1707, 2017.
[3] X. Wang, T. Andritsch, and G. Chen, "Effect of Surface Functionalization on the Dielectric Properties of Polypropylene Aluminium Nitride Nanocomposites," in 2018 IEEE 2nd International Conference on Dielectrics (ICD), 2018, pp. 1-4: IEEE.

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Contributors

Author: Xinyu Wang

Author: Thomas Andritsch

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