Effect of acid modification on electrical properties of carbon nanotube/epoxy resin composites

The dielectric response of oxidized multi-walled carbon nanotube / epoxy resin composites, is investigated with respect to filler content concentration, over a wide temperature and frequency range. Specimens, below the percolation threshold, exhibit similar behaviour to that of the neat epoxy. Two relaxation modes are observed in the low temperature region, attributed to the re-arrangement of small parts of the polymer chain (γ-mode) and the reorientation of polar side groups (β-mode) respectively, where in the high temperature region the evolution of the α-mode is present. Direct current (DC) conduction follows the Vogel – Tamann - Fulcher equation as expected. The dielectric response of specimens, above the percolation threshold, follows the “Random Free Energy Barrier Model”. DC conductivity exhibits Arrhenius temperature dependence with two distinct regions. The activation energies of both regions were evaluated. The contact resistance between two adjacent carbon nanotubes was also calculated. The effective dielectric constant as well as the capacitance of the specimens, above the percolation threshold, can be modulated by means of an applied DC bias voltage.

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Development of Coffee Biochar Filler for the Production of Electrical Conductive Reinforced Plastic

Polymers ◽

10.3390/polym11121916 ◽

2019 ◽

Vol 11 (12) ◽

pp. 1916 ◽

Cited By ~ 13

Author(s):

Mauro Giorcelli ◽

Mattia Bartoli

Keyword(s):

Mechanical Properties ◽

Electrical Conductivity ◽

Electrical Properties ◽

Carbon Black ◽

Epoxy Resin ◽

Resin Composites ◽

Powder Form ◽

Coffee Waste ◽

Reinforced Plastic ◽

Epoxy Resin Composites

In this work we focused our attention on an innovative use of food residual biomasses. In particular, we produced biochar from coffee waste and used it as filler in epoxy resin composites with the aim to increase their electrical properties. Electrical conductivity was studied for the biochar and biochar-based composite in function of pressure applied. The results obtained were compared with carbon black and carbon black composites. We demonstrated that, even if the coffee biochar had less conductivity compared with carbon black in powder form, it created composites with better conductivity in comparison with carbon black composites. In addition, composite mechanical properties were tested and they generally improved with respect to neat epoxy resin.

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Effect of Aramid Fiber Surface State on Properties of Epoxy Resin Composites

Materials Science Forum ◽

10.4028/www.scientific.net/msf.960.167 ◽

2019 ◽

Vol 960 ◽

pp. 167-173

Author(s):

Man Shi Qiu ◽

Ze Hua Pan ◽

Yuan Yuan Zhang ◽

Yong Lan Li ◽

Nai Kui Gao ◽

...

Keyword(s):

Electrical Properties ◽

Epoxy Resin ◽

Surface State ◽

Coupling Agent ◽

Surface States ◽

Aramid Fiber ◽

Breakdown Field ◽

Strength Increase ◽

Resin Composites ◽

Epoxy Resin Composites

The surface state of aramid fiber was modified by coupling agent to characterize the change of the state. The fiber / epoxy resin composites were prepared to study the mechanical and electrical properties and the internal mechanism of how different surface states affect. The results show that, after the treatment with the coupling agent, the surface roughness of the aramid fiber is increased，and the content of Si on the surface reach 5.8%, thus the surface activity is enhanced. At the same time, the treatment makes the properties of composites further improved. When the filling amount of aramid fiber reaches 30 strands, the tensile strength increase by 38.4% due to the coupling agent. In the test of two-layer samples, the breakdown field strength of the composites before and after treatment with coupling agent increased by 15.9% and 20.2%, respectively.Key words: aramid fiber; coupling agent; surface state; mechanical properties; electrical properties

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