scholarly journals Electrical and dielectric properties of kevlar - carbon hybrid fiber / epoxy laminated composites

2011 ◽  
Vol 8 (1) ◽  
pp. 148-154 ◽  
Author(s):  
Baghdad Science Journal
Keyword(s):  
Carbon Fiber ◽  
Temperature Region ◽  
Hybrid Composite ◽  
Dielectric Behavior ◽  
Conductivity Measurements ◽  
Frequency Range ◽  
Hybrid Fiber ◽  
Frequency Exponent ◽  
Number Of Layers ◽  
Electrical And Dielectric Properties

This paper reports a.c., d.c. conductivity and dielectric behavior of Ep-hybrid composite with12 Vol.% Kevlar-Carbon hybrid . D.C. conductivity measurements are conducted on the graded composites by using an electrometer over the temperature range from (293-413) K. It was shown then that conductivity increases by increasing number of Kevlar –Carbon fiber layers (Ep1, Ep2, Ep3), due to the high electrical conductivity of Carbon fiber. To identify the mechanism governing the conduction, the activation energies at low temperature region (LTR) and at high temperature region (HTR) have been calculated. The activation energy values for hybrid composite decrease with increasing number of fiber layers. The a.c. conductivity was measured over frequency range 100 Hz-1MHz. It was found that? ?(?) values increase with increasing frequency according to the relation ? (?)=Aws . The values of frequency exponent (s) were found to increase with number of layers.

Experimentally Study on Mechanical Behavior of CF and GF Hybrid Fiber-Reinforced Plastics

2011 ◽  
Vol 332-334 ◽  
pp. 1082-1086
Author(s):  
Zhi Yun Wu ◽  
Rui Fang Ni
Keyword(s):  
Composite Materials ◽  
Carbon Fiber ◽  
Glass Fiber ◽  
Hybrid Composite ◽  
Tensile Behavior ◽  
Fiber Reinforced ◽  
Hybrid Fiber ◽  
Hybrid Effect ◽  
Reinforced Plastics ◽  
Fiber Reinforced Plastics

The multiaxial warp-knit fabrics of glass fiber or carbon fiber as the structure materials have widely applied to many industries. In this study, in order to combined the advantages of these two fibers, glass fiber and carbon fiber were employed as reinforcement materials in RIMR 135 epoxy resins, and hybrid composites were formed. The tensile behavior of hybrid fiber-reinforced plastics (HFRP) were compared with CFRP and GFRP on the longitudinal orientation . The results suggested that HFRP was high tensile strength and modulus of elasticity. Scanning electron microscopy was used to characterize the morphology of damaged surfaces. The micrographs revealed that CF and GF maintained their own tension behavior in the hybrid composite materials as well in the neat FRP materials. The hybrid effect of HFRP was investigated by the hybrid theory, which was compared to the experimental results. It was confirmed that the tensile behavior of the hybrid composite materials matched the plus hybrid effect.

Using Multiscale Carbon Fiber/Carbon Nanotubes Composites for Damping Applications

2011 ◽  
Author(s):  
Mehran Tehrani ◽  
Masoud Safdari ◽  
Scott W. Case ◽  
Marwan S. Al-Haik
Keyword(s):  
Electron Microscopy ◽  
Carbon Nanotubes ◽  
Carbon Fiber ◽  
Storage Modulus ◽  
Carbon Fibers ◽  
Hybrid Composite ◽  
Loss Modulus ◽  
Ceramic Layer ◽  
Frequency Range ◽  
Catalytic Particles

A novel technique to grow carbon nanotubes (CNTs) on the surface of carbon fibers in a controlled fashion using simple lab set up is developed. Growing CNTs on the surface of carbon fibers will eliminate the problem of dispersion of CNTs in polymeric matrices. The employed synthesis technique retains the attractive feature of uniform distribution of the grown CNTs, low temperature of CNTs’ formation, i.e. 550 °C, via cheap and safe synthesis setup and catalysts. A protective thermal shield of thin ceramic layer and subsequently nickel catalytic particles are deposited on the surface of the carbon fiber yarns using magnetron sputtering. A simple tube furnace setup utilizing nitrogen, hydrogen and ethylene (C2H4) were used to grow CNTs on the carbon fiber yarns. Scanning electron microscopy revealed a uniform areal growth over the carbon fibers where the catalytic particles had been sputtered. The structure of the grown multiwall carbon nanotubes was characterized with the aid of transmission electron microscopy (TEM). Dynamical mechanical analysis (DMA) was employed to measure the loss and storage moduli of the hybrid composite together with the reference raw carbon fiber composite and the composite for which only ceramic and nickel substrates had been deposited on. The DMA tests were conducted over a frequency range of 1–40 Hz. Although the storage modulus remained almost unchanged over the frequency range for all samples, the loss modulus showed a frequency dependent behavior. The hybrid composite obtained the highest loss modulus among other samples with an average increase of approximately 25% and 55% compared to composites of the raw and ceramic/nickel coated carbon fibers, respectively. This improvement occurred while the average storage modulus of the hybrid composite declined by almost 9% and 15% compared to the composites of reference and ceramic/nickel coated samples, respectively. The ultimate strength and elastic moduli of the samples were measured using standard ASTM tensile test. Results of this study show that while the addition of the ceramic layer protects the fibers from mechanical degradation it abolishes the mechanisms by which the composite dissipates energy. On the other hand, with almost no compromise in weight, the hybrid composites are good potential candidate for damping applications. Furthermore, the addition of CNTs could contribute to improving other mechanical, electrical and thermal properties of the hybrid composite.

scholarly journals Enhanced Impact Properties of Hybrid Composites Reinforced by Carbon Fiber and Polyimide Fiber

Polymers ◽  
2021 ◽  
Vol 13 (16) ◽  
pp. 2599
Author(s):  
Boyao Wang ◽  
Bin He ◽  
Zhanwen Wang ◽  
Shengli Qi ◽  
Daijun Zhang ◽  
...  
Keyword(s):  
Carbon Fiber ◽  
Failure Modes ◽  
Flexural Modulus ◽  
Charpy Impact ◽  
Fiber Reinforced Composites ◽  
Stacking Sequence ◽  
Reinforced Composites ◽  
Fiber Reinforced ◽  
Hybrid Fiber ◽  
Polyimide Fiber

A series of hybrid fiber-reinforced composites were prepared with polyimide fiber and carbon fiber as the reinforcement and epoxy resin as the matrix. The influence of stacking sequence on the Charpy impact and flexural properties of the composites as well as the failure modes were studied. The results showed that hybrid fiber-reinforced composites yielded nearly 50% increment in Charpy impact strength compared with the ones reinforced by carbon fiber. The flexural performance was significantly improved compared with those reinforced solely by polyimide fibers and was greatly affected by the stacking sequence. The specimens with compressive sides distributed with carbon fiber possessed higher flexural strength, while those holding a sandwich-like structure with carbon fiber filling between the outer layers displayed a higher flexural modulus.

scholarly journals A.C conductivity and dielectric properties of (PVA/ PEO) blends doped with MWCNTs

2019 ◽  
Vol 14 (30) ◽  
pp. 64-72
Author(s):  
Ahmad A. Hasan
Keyword(s):  
Electrical Conductivity ◽  
Dielectric Properties ◽  
The Other ◽  
Poly Vinyl Alcohol ◽  
Conductivity Measurements ◽  
Frequency Range ◽  
Maximum Value ◽  
Multi Walled Carbon Nanotube ◽  
Poly Ethylene Oxide ◽  
Poly Ethylene

A.C electrical conductivity and dielectric properties for poly(vinyl alcohol) (PVA) /poly (ethylene oxide) (PEO) blends undopedand doped with multi-walled carbon nanotube (MWCNTs) withdifferent concentrations (1, and 3 wt %) in the frequency range(25x103 - 5x106 Hz) were investigated. Samples of (PVA/PEO)blends undoped and doped with MWCNTs were prepared usingcasting technique. The electrical conductivity measurements showedthat σA.C is frequency dependent and obey the relation σA.C =Aωs forundoped and doped blends with 1% MWCNTs, while it is frequencyindependent with increases of MWCNTs content to 3%. Theexponent s showed proceeding increase with the increase of PEOratio (≥50%) for undoped blends samples, while s value for dopedblends exhibits to change in different manner, i.e. s increases andreach maximum value at 50/50 PVA/PEO, then decreases forresidual doped blends samples with 1% MWCNTs on the other handthe exponent s decrease and reach minimum value at 50/50PVA/PEO for samples doped with 3% MWCNTs, then return toincrease. The results explained in different terms.

scholarly journals Soil Moisture Estimate Uncertainties from the Effect of Soil Texture on Dielectric Semiempirical Models

2020 ◽  
Vol 12 (14) ◽  
pp. 2343
Author(s):  
Jing Liu ◽  
Qinhuo Liu
Keyword(s):  
Soil Moisture ◽  
Water Content ◽  
Soil Texture ◽  
Dielectric Behavior ◽  
Volumetric Water Content ◽  
Frequency Range ◽  
Dielectric Model ◽  
Texture Effect ◽  
Semi Empirical ◽  
Semiempirical Models

Soil texture has been shown to affect the dielectric behavior of soil over the entire frequency range. Three universally employed dielectric semiempirical models (SEMs), the Dobson model, the Wang–Schmugge model and the Mironov model, as well as a new improved SEM known as the soil semi-empirical mineralogy-related-to-water dielectric model (SSMDM), incorporate a significant soil texture effect in different ways. In this paper, soil moisture estimate uncertainties from the effect of soil texture on these four SEMs are systematically and widely investigated over all soil texture cases at different frequencies between 1.4 and 18 GHz for volumetric water content levels between 0.0 and 0.4 m3/m3 from the perspective of two aspects: soil dielectric model discordance and soil texture discordance. Firstly, the effect of soil texture on these four dielectric SEMs is analyzed. Then, soil moisture estimate uncertainties due to the effect of soil texture are carefully investigated. Finally, the applicability of these SEMs is discussed, which can supply references for their choice. The results show that soil moisture estimate uncertainties are small and satisfy the 4% volumetric water content retrieval requirement in some cases. However, in other cases, it may contribute relatively significant uncertainties to soil moisture estimates and correspond to a difference that exceeds the 4% volumetric water content requirement, with potential for the largest deviations to exceed 0.22 m3/m3.

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