Effect of Interfacial Polarization and Water Absorption on the Dielectric Properties of Epoxy-Nanocomposites

Effect of Interfacial Polarization and Water Absorption on the Dielectric Properties of Epoxy-Nanocomposites

Marx, Philipp (Polymer Competence Center Leoben; Montanuniversität Leoben)
Wanner, Andrea (Polymer Competence Center Leoben; Montanuniversität Leoben)
Zhang, Zucong (Polymer Competence Center Leoben)
Jin, H. (TU Delft DC systems, Energy conversion & Storage)
Tsekmes, I.A. (TU Delft DC systems, Energy conversion & Storage; Montanuniversität Leoben)
Smit, J.J. (TU Delft EEMS - General)
Kern, Wolfgang (Polymer Competence Center Leoben; Montan University of Leoben)
Wiesbrock, Frank (Polymer Competence Center Leoben)

2017-05-28

Five types of nanofillers, namely, silica, surface-silylated silica, alumina, surface-silylated alumina, and boron nitride, were tested in this study. Nanocomposites composed of an epoxy/amine resin and one of the five types of nanoparticles were tested as dielectrics with a focus on (i) the surface functionalization of the nanoparticles and (ii) the water absorption by the materials. The dispersability of the nanoparticles in the resin correlated with the composition (OH content) of their surfaces. The interfacial polarization of the thoroughly dried samples was found to increase at lowered frequencies and increased temperatures. The β relaxation, unlike the interfacial polarization, was not significantly increased at elevated temperatures (below the glass-transition temperature). Upon the absorption of water under ambient conditions, the interfacial polarization increased significantly, and the insulating properties decreased or even deteriorated. This effect was most pronounced in the nanocomposite containing silica, and occurred as well in the nanocomposites containing silylated silica or non-functionalized alumina. The alternating current (AC) breakdown strength of all specimens was in the range of 30 to 35 kV·mm−1. In direct current (DC) breakdown tests, the epoxy resin exhibited the lowest strength of 110 kV·mm−1; the nanocomposite containing surface-silylated alumina had a strength of 170 kV·mm−1. In summary, water absorption had the most relevant impact on the dielectric properties of nanocomposites containing nanoparticles, the surfaces of which interacted with the water molecules. Nanocomposites containing silylated alumina particles or boron nitride showed the best dielectric properties in this study.

epoxy resins
nanoparticles
surface functionalization
silylating agent
water uptake
permittivity
loss factor
interfacial polarization
thermal conductivity

http://resolver.tudelft.nl/uuid:a29ccc13-6e1c-4919-ba0a-9ccbd599d7ef

https://doi.org/10.3390/polym9060195

2073-4360

Polymers, 9 (6), 1-16

Special Issue "Polymer Nanocomposites"

Institutional Repository

contribution to periodical

© 2017 Philipp Marx, Andrea Wanner, Zucong Zhang, H. Jin, I.A. Tsekmes, J.J. Smit, Wolfgang Kern, Frank Wiesbrock