Negative Permittivity of CNTs–Epoxy Composites Prepared by Cryomilling

2015 ◽  
Vol 815 ◽  
pp. 607-610
Author(s):  
Qing Hou ◽  
Run Hua Fan ◽  
Zi Dong Zhang ◽  
Ke Lan Yan ◽  
Chuan Bing Cheng ◽  
...  
Keyword(s):  
Dielectric Properties ◽  
Epoxy Resin ◽  
Liquid Nitrogen ◽  
Plasma Oscillation ◽  
Liquid Nitrogen Temperature ◽  
Negative Permittivity ◽  
Epoxy Composites

In this paper, epoxy resin was used as matrix to prepare composite cryomilling at liquid nitrogen temperature in which the content of CNTs powder vary from 25 wt% to 40 wt%. The microstructure and dielectric properties of the composite were analyzed by SEM and RF impedance material analyzer. The result showed that permittivity of the composites turned negative after the CNTs reached certain content. The plasma oscillation of delocalized electrons in CNTs conductive networks causes negative permittivity phenomenon.

Cryogenic Interlaminar Properties of PBO Fiber/Epoxy Composites

2011 ◽  
Vol 391-392 ◽  
pp. 1445-1449
Author(s):  
Chun Hua Zhang ◽  
Shi Lin Luan ◽  
Xiu Song Qian ◽  
Bao Hua Sun ◽  
Wen Sheng Zhang
Keyword(s):  
Liquid Nitrogen ◽  
Room Temperature ◽  
Liquid Nitrogen Temperature ◽  
Epoxy Composites ◽  
Bending Test ◽  
Test Results ◽  
Sem Images ◽  
Three Point Bending ◽  
Pbo Fiber ◽  
Interlaminar Shear

The influences of low temperature on the interlaminar properties for PBO fiber/epoxy composites have been studied at liquid nitrogen temperature (77 K) in terms of three point bending test. Results showed that the interlaminar shear strength at 77 K were significantly higher than those at room temperature (RT). For the analysis of the test results, the tensile behaviors of epoxy resin at both room temperature and liquid nitrogen temperature were investigated. The interface between fiber and matrix was observed using SEM images.

Tuning of thermal and dielectric properties for epoxy composites filled with electrospun alumina fibers and graphene nanoplatelets through hybridization

2015 ◽  
Vol 3 (27) ◽  
pp. 7195-7202 ◽  
Author(s):  
Jun-Wei Zha ◽  
Tian-Xing Zhu ◽  
Yun-Hui Wu ◽  
Si-Jiao Wang ◽  
Robert K. Y. Li ◽  
...  
Keyword(s):  
Dielectric Properties ◽  
Epoxy Resin ◽  
Electronics Packaging ◽  
Graphene Nanoplatelets ◽  
Electrical Insulation ◽  
Epoxy Composites ◽  
Alumina Fibers ◽  
Excellent Adhesion ◽  
Cure Shrinkage

Epoxy resin is widely used for electrical and electronics packaging in various forms due to its excellent adhesion, low cure shrinkage and good electrical insulation.

Experimental study on the mechanical behavior and microstructural assessment of Kevlar/epoxy composites at liquid nitrogen temperature

2014 ◽  
Vol 23 (3-4) ◽  
pp. 95-100 ◽  
Author(s):  
Sanghamitra Sethi ◽  
Bankim Chandra Ray
Keyword(s):  
Mechanical Behavior ◽  
Liquid Nitrogen ◽  
Failure Modes ◽  
Progressive Failure ◽  
Liquid Nitrogen Temperature ◽  
Woven Fabric ◽  
Epoxy Composites ◽  
Interlaminar Shear ◽  
Three Point Bend Test ◽  
Point Bend

AbstractThe present investigation emphasized the understanding of the mechanical behavior and progressive failure modes of Kevlar/epoxy-reinforced laminated composites subjected to a three-point bend test at liquid nitrogen (LN2) temperature (77 K). The tests were conducted on the woven fabric laminates with different loading speeds and characterized by scanning electron microscopy (SEM). The effect of LN2 temperature on the interlaminar shear strength (ILSS) of Kevlar/epoxy composites with various loading speeds was observed. The results indicate that the values of ILSS were increased at higher crosshead speeds compared to ambient temperature. The fibrillation progression and matrix failure (riverline marking) was observed by SEM. A change in crosshead speed may result in the variation of failure modes.

scholarly journals Preparation of a Chemically Reduced Graphene Oxide Reinforced Epoxy Resin Polymer as a Composite for Electromagnetic Interference Shielding and Microwave-Absorbing Applications

Polymers ◽  
2018 ◽  
Vol 10 (11) ◽  
pp. 1180 ◽  
Author(s):  
Ahmad Ahmad ◽  
Sidek Ab Aziz ◽  
Zulkifly Abbas ◽  
Suzan Obaiys ◽  
Ahmad Khamis ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
Dielectric Properties ◽  
Epoxy Resin ◽  
Reduced Graphene Oxide ◽  
Microwave Absorption ◽  
Electromagnetic Interference ◽  
Epoxy Composites ◽  
Debye Relaxation ◽  
Reduced Graphene ◽  
Chemically Reduced Graphene Oxide

The preparation of chemically reduced graphene oxide (rGO) and the optimization of epoxy resins’ properties using micro or nanofillers are now common practices. rGO nanoparticles (60 nm) based on an epoxy resin polymer were prepared at the concentrations of 0, 1, 2, 3, 4, and 5% weight percentage with fixed 6-mm thicknesses. The dielectric properties of the composites were measured by the reflection/transmission technique in connection with a vector network analyser (VNA) at a frequency range of 8–12 GHz. The microwave absorption and shielding effectiveness properties were calculated by using the reflection S11 and transmission S21 results. The microstructure and morphology of the polymer and the rGO/cured epoxy composites were studied by field emission scanning electron microscopy (FE-SEM), Fourier-transform infrared (FT-IR) spectroscopy, and the X-ray Diffraction (X-RD) technique for characterizing crystalline materials. The dielectric and other properties of the rGO/cured epoxy composites were investigated based on the filler load and frequency. It was found that the applied frequency and the filler concentrations affected the dielectric properties of the rGO/cured epoxy composites. The results showed that the introduction of rGO particles to the composites increased their dielectric properties smoothly. The study of the dependence on frequency of both the dielectric constant ε′ and the dielectric loss ε″ showed a decrease in both quantities with increasing frequency, indicating a normal behaviour of the dielectrics. Cole–Cole plots were drawn with ε′ and ε″. A theoretical simulation in terms of the Cole–Cole dispersion law indicates that the Debye relaxation processes in the rGO/cured epoxy composites are improved due to the presence of the rGO filler. Moreover, with the addition of rGO as a filler into the Epoxy matrix, it now exhibits promise as a lightweight material for microwave absorption as well as an effective electromagnetic interference (EMI) shielding material.

Assessment of Microstructural Integrity of Glass/Epoxy Composites at Liquid Nitrogen Temperature

2007 ◽  
Vol 26 (11) ◽  
pp. 1083-1089 ◽  
Author(s):  
M. Surendra Kumar ◽  
Nirmal Chawla ◽  
Asima Priyadarsini ◽  
Itishree Mishra ◽  
B.C. Ray
Keyword(s):  
Liquid Nitrogen ◽  
Liquid Nitrogen Temperature ◽  
Epoxy Composites ◽  
Microstructural Integrity
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