Dielectric Relaxation Characteristics of Epoxy Resin Modified with Hydroxyl-Terminated Nitrile Rubber

Utilizing liquid rubber to toughen epoxy resin is one of the most mature and promising methods. However, the dielectric relaxation characteristics of the epoxy/liquid rubber composites have not been studied systematically, while the relaxation behaviours are a critical factor for both micro and macro properties. In this paper, hydroxyl-terminated liquid nitrile rubber (HTBN) is employed to reinforce a kind of room-temperature-cured epoxy resin. The dielectric spectrum is measured and analysed. Results show that two relaxation processes are introduced in the binary composites. The α relaxation of HTBN shows a similar temperature dependence with the β relaxation of epoxy resin. The interfacial polarization leads to an increase of complex permittivity, which reaches its maximum at 70 °C. In addition, affected by interfacial polarization, the thermionic polarization is inhibited, and the samples with filler ratios of 15% and 25% show lower DC-conductivity below 150 °C. In addition, the α relaxation and thermionic polarization of epoxy resin obey the Vogel‒Fulcher‒Tammann law, while the interfacial polarization and DC-conductivity satisfy with the Arrhenius law. Furthermore, the fitting results of the Vogel temperature of α relaxation, glass transition temperature, apparent activation energy of interfacial polarization and DC-conductivity all decline with HTBN content. These results can provide a reference and theoretical guidance for the assessment of dielectric properties and the improvement of the formulation of liquid-rubber-toughened epoxy resin.

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Magneto-Electric Response and Functionality in Barium Ferrite/Barium Titanate/Epoxy Resin Nanocomposites

Journal of Advanced Physics ◽

10.1166/jap.2017.1293 ◽

2017 ◽

Vol 6 (1) ◽

pp. 69-75 ◽

Cited By ~ 1

Author(s):

A. Kanapitsas ◽

G. C. Psarras ◽

C. Tsonos ◽

Th. Speliotis ◽

A. C. Patsidis ◽

...

Keyword(s):

Electron Microscopy ◽

Barium Titanate ◽

Epoxy Resin ◽

Barium Ferrite ◽

Interfacial Polarization ◽

Hybrid Nanocomposites ◽

Resin Matrix ◽

Electric Response ◽

Relaxation Processes ◽

Barium Titanate Nanoparticles

Hybrid nanocomposites with barium ferrite and barium titanate nanoparticles embedded within an epoxy resin matrix, were prepared and studied, varying the fillers content. The morphology of the fabricated specimens was examined by means of scanning electron microscopy and energy dispersive X-ray spectroscopy. Dielectric and magnetic properties of the nanocomposites were investigated via broadband dielectric spectroscopy and magnetization tests, respectively. Fine dispersions of nanofillers were detected via electron microscopy in all studied cases. Dielectric permittivity increases with diminishing frequency and increasing temperature and filler content. Recorded relaxation processes are attributed to interfacial polarization, between matrix and nanoparticles, glass to rubber transition of the polymer matrix (α-relaxation), and re-arrangement of polar-side groups of the main polymer chain (β-relaxation). Magnetization and magnetic saturation increase with the amount of barium ferrite nanoparticles.

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Study of the Molecular Mobility of Polysaccharide Solid Thin Layers by Dielectric Relaxation Spectroscopy

MRS Proceedings ◽

10.1557/proc-500-157 ◽

1997 ◽

Vol 500 ◽

Author(s):

K. Liedermann ◽

L. Lapčík ◽

S. Desmedt

Keyword(s):

Dielectric Relaxation ◽

Low Frequency ◽

Thin Layers ◽

Side Chain ◽

Relaxation Processes ◽

Dielectric Relaxation Spectroscopy ◽

Frequency Range ◽

Polar Groups ◽

Calculated Activation Energy ◽

Β Relaxation

ABSTRACTTemperature dependence of measured dielectric relaxation spectra (DRS) in the frequency range 20 Hz - 1 MHz of hydroxyethylcellulose (HEC) are in the temperature range 100 – 350 K. of Arrhenius character with one relaxation process at 150 – 250 K. This process reflects most probably β-relaxation of the side chain groups. Calculated activation energy of this process was 5730 kJ/mole. Four types of polysaccharides were studied at 293 K temperature: hyaluronic acid (HA), chondroitin sulfate (CHS), HEC and carboxymethylcellulose (CMC), in the low-frequency range 10−5 - 100 Hz. Measured dielectric spectra were interpreted as sum of one A.C. conductivity process and of up to two relaxation processes. The relaxation processes were described by means of the Havriliak-Negami formula and their parameters were related to the molecular structure of the polymers. The low value of a in CHS is related to its strong coupling due to the presence of two polar groups in its monomeric unit, whereas low values of α × β are interpreted as being due to the strong steric hindrances caused by long pendants present in HEC.

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Correlation between mechanical and dielectric relaxation processes in epoxy resin composites with nano- and micro-fillers

Electronics and Communications in Japan ◽

10.1002/ecj.11420 ◽

2012 ◽

Vol 95 (9) ◽

pp. 1-9 ◽

Cited By ~ 3

Author(s):

Mayumi Hyuga ◽

Toshikatsu Tanaka ◽

Yoshimichi Ohki ◽

Takahiro Imai ◽

Miyuki Harada ◽

...

Keyword(s):

Dielectric Relaxation ◽

Epoxy Resin ◽

Relaxation Processes ◽

Resin Composites ◽

Epoxy Resin Composites ◽

Micro Fillers

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Modelling of dielectric relaxation processes of epoxy-resin filled with carbon black particles

Physica B Condensed Matter ◽

10.1016/j.physb.2013.10.009 ◽

2014 ◽

Vol 433 ◽

pp. 62-66 ◽

Cited By ~ 14

Author(s):

M. El Hasnaoui ◽

A. Triki ◽

M.E. Achour ◽

M. Arous

Keyword(s):

Carbon Black ◽

Dielectric Relaxation ◽

Epoxy Resin ◽

Relaxation Processes

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Correlation between Mechanical and Dielectric Relaxation Processes in Epoxy Resin Composites with Nano- and Micro-fillers

IEEJ Transactions on Fundamentals and Materials ◽

10.1541/ieejfms.131.1041 ◽

2011 ◽

Vol 131 (12) ◽

pp. 1041-1047 ◽

Cited By ~ 4

Author(s):

Mayumi Hyuga ◽

Toshikatsu Tanaka ◽

Yoshimichi Ohki ◽

Takahiro Imai ◽

Miyuki Harada ◽

...

Keyword(s):

Dielectric Relaxation ◽

Epoxy Resin ◽

Relaxation Processes ◽

Resin Composites ◽

Epoxy Resin Composites ◽

Micro Fillers

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Effect of Toughening with Different Liquid Rubber on Dielectric Relaxation Properties of Epoxy Resin

Polymers ◽

10.3390/polym12020433 ◽

2020 ◽

Vol 12 (2) ◽

pp. 433 ◽

Cited By ~ 2

Author(s):

Chuang Wang ◽

Qing Sun ◽

Kang Lei ◽

Chi Chen ◽

Lixiao Yao ◽

...

Keyword(s):

Epoxy Resin ◽

High Performance ◽

Critical Role ◽

Relative Dielectric Constant ◽

Interfacial Polarization ◽

Rubber Composites ◽

Liquid Rubber ◽

Rubber Composite ◽

Industrial Use ◽

Dielectric Relaxation Properties

Liquid rubber is a common filler introduced to epoxy resin to improve its toughness for electrical insulation and electronic packaging applications. The improvement of toughness by adding liquid rubber to epoxy resin leads to the variation of its dielectric properties and relaxation behaviors and it has not been systematically studied yet. In this paper, four kinds of liquid rubber with different polarity were selected and the corresponding epoxy/liquid rubber composites have been prepared. By analyzing the temperature and frequency dependence of dielectric spectra, we found that a lower relative dielectric constant and dielectric loss of the epoxy/liquid rubber composites could be achieved by reducing the polarity of liquid rubber filler. These results also confirm that the polarity of liquid rubber plays a critical role in determining the α transition relaxation strength of rubber molecules at about −50 °C, as well as the relaxation time of interfacial polarization. In addition, the conductivity of rubber phase with different polarity were investigated by studying the apparent activation energy of interfacial polarization calculated from the Arrhenius plot. This study can provide a theoretical basis for designing high-performance epoxy/liquid rubber composite insulating materials for industrial use.

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Relaxation dynamics of Ni/epoxy composites studied by dielectric relaxation spectroscopy

Journal of Elastomers & Plastics ◽

10.1177/0095244319847494 ◽

2019 ◽

Vol 52 (4) ◽

pp. 304-321 ◽

Cited By ~ 1

Author(s):

Li Xu ◽

Wenying Zhou ◽

Bo Li ◽

Yujia Kou ◽

Huiwu Cai ◽

...

Keyword(s):

Dielectric Relaxation ◽

Interfacial Polarization ◽

Wide Frequency Range ◽

Epoxy Composites ◽

Relaxation Processes ◽

Dielectric Relaxation Spectroscopy ◽

Relaxation Dynamics ◽

Broadband Dielectric Spectroscopy ◽

Space Charges ◽

Increasing Temperature

Dynamic dielectric properties of nickel (Ni)/epoxy composites are investigated by broadband dielectric spectroscopy over a wide frequency range (approximately 1–107 Hz) and temperature range (approximately −20 to 200°C). Multiple dielectric relaxation processes in the Ni/epoxy composites are identified, corresponding to conductivity, interfacial polarization (IP), and α-relaxation. With increasing temperature, both dielectric permittivity and loss of composites increase, arising from enhanced dipolar mobility; approaching the glass transition temperature ( T g), a clear α-relaxation appears, which can be attributed to the onset of cooperative chain movement. Further increasing temperature activates the long-range movement of space charges, as manifested by an IP superimposed on the ionic conductivity. A transition from insulator (below T g) to semiconductor (above T g) is also observed for the studied composite system.

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Synergistical Performance Modification of Epoxy Resin by Nanofillers and Carboxyl-Terminated Liquid Nitrile–Butadiene Rubber

Materials ◽

10.3390/ma14164601 ◽

2021 ◽

Vol 14 (16) ◽

pp. 4601

Author(s):

Yuanjin Liu ◽

Lixiao Yao ◽

Yue Bu ◽

Qing Sun

Keyword(s):

Epoxy Resin ◽

Resin Matrix ◽

Relaxation Processes ◽

Butadiene Rubber ◽

Voltage Level ◽

Nitrile Butadiene Rubber ◽

Nano Alumina ◽

The Matrix ◽

Thermally Conductive ◽

Relaxation Characteristics

Epoxy composite materials are widely used in power equipment. As the voltage level increases, the requirement of material properties, including electrical, thermal, and mechanical, has also increased. Introducing thermally conductive nanofiller to the epoxy/liquid rubber composites system is an effective approach to improve heat performance, but the effects of thermally conductive nanofillers on relaxation characteristics remain unclarified. In this paper, nano-alumina (nano-Al2O3) and nano-boron nitride (nano-BN) have been employed to modify the epoxy/carboxyl-terminated liquid nitrile–butadiene rubber (epoxy/CTBN) composites system. The thermal conductivity and glass transition temperature of different formula systems have been measured. The effect of the nanofillers on the relaxation behaviors of the resin matrix has been investigated. Results show that the different kinds of nanofillers will introduce different relaxation processes into the matrix and increase the conductivity at the same time. This study can provide a theoretical basis for the synergistic improvement of multiple properties of epoxy resin composites.

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