scholarly journals Improved Performance of Graphene in Heat Dissipation when Combined with an Orientated Magnetic Carbon Fiber Skeleton under Low-Temperature Thermal Annealing

Materials ◽  
2019 ◽  
Vol 12 (6) ◽  
pp. 954 ◽  
Author(s):  
Jing Li ◽  
Rubai Lei ◽  
Jinfeng Lai ◽  
Xuyang Chen ◽  
Yang Li

The high thermal conductivity and stability, outstanding mechanical properties, and low weight make graphene suitable for many applications in the realm of thermal management, especially in high integration systems. Herein, we report a high-performance, low-temperature reduced graphene oxide/magnetic carbon fiber composite film. Magnetic carbon fibers were prepared using a co-precipitation method, and the graphene oxide solution was prepared using an improved Hummers’ method. The magnetic carbon fibers were orientated by magnetite and immersed in the graphene oxide solution during filtration, followed by annealing at 800 °C. The composite film exhibited improved thermal conductivity (over 600 W/m·K) and mechanical properties (tensile strength of 37.1 MPa and bending cycle of up to 8000). The experimental results illustrate that the graphene in the composite membrane provides heat transfer channels to promote in-plane thermal conductivity, while the magnetic carbon fiber acts as a scaffold to reinforce the mechanical properties and improve the quality of the graphene. Due to the synergistic effect of the graphene and magnetic carbon, this composite has wide potential applications in heat dissipation.

2021 ◽  
Vol 36 (4) ◽  
pp. 417-422
Author(s):  
Y. Hamid ◽  
P. Svoboda

Abstract Ethylene-butene copolymer (EBC)/carbon-fiber (CF) composites can be utilized as an electromechanical material due to their ability to change electric resistance with mechanical strain. The electro-mechanical properties and thermal conductivity of ethylene butene copolymer (EBC) composites with carbon fibers were studied. Carbon fibers were introduced to EBC with various concentrations (5 to 25 wt%). The results showed that carbon fibers’ addition to EBC improves the electric conductivity up to 10 times. Increasing the load up to 2.9 MPa will raise the electric resistance change by 4 500% for a 25% fiber sample. It is also noted that the EBC/CF composites’ electric resistance underwent a dramatic increase in raising the strain. For example, the resistance change was around 13 times higher at 15% strain compared to 5% strain. The thermal conductivity tests showed that the addition of carbon fibers increases the thermal conductivity by 40%, from 0.19 to 0.27 Wm–1K–1.


1995 ◽  
Vol 383 ◽  
Author(s):  
Jyh-Ming Ting

ABSTRACTIn contrast to the form in which other carbon fibers are produced, vapor grown carbon fiber (VGCF) is produced from gas phase precursors in the form of individual fibers of discrete lengths. VGCF can be harvested as a mat of semi-aligned, semicontinuous fibers, with occasional fiber branching and curling. The use of VGCF mats as reinforcement result in composites which exhibit unique microstructure and physical properties that are not observed in other types of carbon composites. This paper describes the processing of VGCF mats reinforced carbon composites, and its unique microstructure and properties. Utilization of fiber tensile properties, as well as thermal conductivity, in the composites is discussed. Comparison of experimental results from various VGCF composites to theory indicates that mechanical properties are more strongly affected by characteristics of VGCF mat than are thermal conductivity. The implications of this relationship favors applications for thermal management where structural demands are less stringent.


Materials ◽  
2020 ◽  
Vol 13 (2) ◽  
pp. 317 ◽  
Author(s):  
Guang-jie Yuan ◽  
Jie-Fei Xie ◽  
Hao-Hao Li ◽  
Bo Shan ◽  
Xiao-Xin Zhang ◽  
...  

Thermally reduced graphene oxide/carbon nanotube (rGO/CNT) composite films were successfully prepared by a high-temperature annealing process. Their microstructure, thermal conductivity and mechanical properties were systematically studied at different annealing temperatures. As the annealing temperature increased, more oxygen-containing functional groups were removed from the composite film, and the percentage of graphene continuously increased. When the annealing temperature increased from 1100 to 1400 °C, the thermal conductivity of the composite film also continuously increased from 673.9 to 1052.1 W m−1 K−1. Additionally, the Young’s modulus was reduced by 63.6%, and the tensile strength was increased by 81.7%. In addition, the introduction of carbon nanotubes provided through-plane thermal conduction pathways for the composite films, which was beneficial for the improvement of their through-plane thermal conductivity. Furthermore, CNTs apparently improved the mechanical properties of rGO/CNT composite films. Compared with the rGO film, 1 wt% CNTs reduced the Young’s modulus by 93.3% and increased the tensile strength of the rGO/CNT composite film by 60.3%, which could greatly improve its flexibility. Therefore, the rGO/CNT composite films show great potential for application as thermal interface materials (TIMs) due to their high in-plane thermal conductivity and good mechanical properties.


2003 ◽  
Vol 774 ◽  
Author(s):  
Janice L. McKenzie ◽  
Michael C. Waid ◽  
Riyi Shi ◽  
Thomas J. Webster

AbstractSince the cytocompatibility of carbon nanofibers with respect to neural applications remains largely uninvestigated, the objective of the present in vitro study was to determine cytocompatibility properties of formulations containing carbon nanofibers. Carbon fiber substrates were prepared from four different types of carbon fibers, two with nanoscale diameters (nanophase, or less than or equal to 100 nm) and two with conventional diameters (or greater than 200 nm). Within these two categories, both a high and a low surface energy fiber were investigated and tested. Astrocytes (glial scar tissue-forming cells) and pheochromocytoma cells (PC-12; neuronal-like cells) were seeded separately onto the substrates. Results provided the first evidence that astrocytes preferentially adhered on the carbon fiber that had the largest diameter and the lowest surface energy. PC-12 cells exhibited the most neurites on the carbon fiber with nanodimensions and low surface energy. These results may indicate that PC-12 cells prefer nanoscale carbon fibers while astrocytes prefer conventional scale fibers. A composite was formed from poly-carbonate urethane and the 60 nm carbon fiber. Composite substrates were thus formed using different weight percentages of this fiber in the polymer matrix. Increased astrocyte adherence and PC-12 neurite density corresponded to decreasing amounts of the carbon nanofibers in the poly-carbonate urethane matrices. Controlling carbon fiber diameter may be an approach for increasing implant contact with neurons and decreasing scar tissue formation.


Polymers ◽  
2018 ◽  
Vol 10 (12) ◽  
pp. 1319 ◽  
Author(s):  
Ran Li ◽  
Huiping Lin ◽  
Piao Lan ◽  
Jie Gao ◽  
Yan Huang ◽  
...  

Lightweight electromagnetic interference shielding cellulose foam/carbon fiber composites were prepared by blending cellulose foam solution with carbon fibers and then freeze drying. Two kinds of carbon fiber (diameter of 7 μm) with different lengths were used, short carbon fibers (SCF, L/D = 100) and long carbon fibers (LCF, L/D = 300). It was observed that SCFs and LCFs built efficient network structures during the foaming process. Furthermore, the foaming process significantly increased the specific electromagnetic interference shielding effectiveness from 10 to 60 dB. In addition, cellulose/carbon fiber composite foams possessed good mechanical properties and low thermal conductivity of 0.021–0.046 W/(m·K).


2020 ◽  
Vol 40 (5) ◽  
pp. 415-420 ◽  
Author(s):  
Yasin Altin ◽  
Hazal Yilmaz ◽  
Omer Faruk Unsal ◽  
Ayse Celik Bedeloglu

AbstractThe interfacial interaction between the fiber and matrix is the most important factor which influences the performance of the carbon fiber-epoxy composites. In this study, the graphitic surface of the carbon fibers was modified with graphene oxide nanomaterials by using a spray coating technique which is an easy, cheap, and quick method. The carbon fiber-reinforced epoxy matrix composites were prepared by hand layup technique using neat carbon fibers and 0.5, 1 and 2% by weight graphene oxide (GO) modified carbon fibers. As a result of SEM analysis, it was observed that GO particles were homogeneously coated on the surface of the carbon fibers. Furthermore, Young's modulus increased from 35.14 to 43.40 GPa, tensile strength increased from 436 to 672 MPa, and the elongation at break was maintained around 2% even in only 2% GO addition.


2018 ◽  
Vol 225 ◽  
pp. 01022
Author(s):  
Falak O. Abasi ◽  
Raghad U. Aabass

Newer manufacturing techniques were invented and introduced during the last few decades; some of them were increasingly popular due to their enhanced advantages and ease of manufacturing over the conventional processes. Polymer composite material such as glass, carbon and Kevlar fiber reinforced composite are popular in high performance and light weight applications such as aerospace and automobile fields. This research has been done by reinforcing the matrix (epoxy) resin with two kinds of the reinforcement fibers. One weight fractions were used (20%) wt., Epoxy reinforced with chopped carbon fiber and second reinforcement was epoxy reinforced with hybrid reinforcements Kevlar fiber and improved one was the three laminates Kevlar fiber and chopped carbon fibers reinforced epoxy resin. After preparation of composite materials some of the mechanical properties have been studied. Four different fiber loading, i.e., 0 wt. %, 20wt. % CCF, 20wt. % SKF, AND 20wt. %CCF + 20wt. % SKF were taken for evaluating the above said properties. The thermal and mechanical properties, i.e., hardness load, impact strength, flexural strength (bending load), and thermal conductivity are determined to represent the behaviour of composite structures with that of fibers loading. The results show that with the increase in fiber loading the mechanical properties of carbon fiber reinforced epoxy composites increases as compared to short carbon fiber reinforced epoxy composites except in case of hardness, short carbon fiber reinforced composites shows better results. Similarly, flexural strength test, Impact test, and Brinell hardness test the results show the flexural strength, impact strength of the hybrid composites values were increased with existence of Kevlar fibers, while the hardness was decrease. But the reinforcement with carbon fibers increases the hardness and decreases other tests.


Sign in / Sign up

Export Citation Format

Share Document