Carbon Fibers

Power dissipation is expected to increase exponentially to 150-250 W per chip over the next decade. To manage this large heat output, it is necessary to minimize the thermal resistance between the chip and a heat dissipation unit that the device is attached to. It is therefore important to further improve the thermal performance of thermal interface materials (TIMs), which can be achieved through 1) improvement of the bulk thermal conductivity of TIMs; and/or 2) reduction of interfacial thermal resistances between the TIM and the device and/or TIM and the heat dissipation unit. The latter improvement may be obtained by enhanced physical properties of TIMs (e.g., viscosity or wetting ability) and/or surface modification of the heat dissipation unit or the inactive side of the device. Researchers have tried to take advantage of the high 1D thermal conductivities of graphite fibers, and more recently of carbon nanotubes (CNT), to reduce the thermal resistance between the chip and the h...

Cellulose derivative fibers were prepared via phosphorylation of cellulose with the ionic liquid (IL) 1,3-dimethylimidazolium methyl-H-phosphonate [MMIM] + [MMP] − in the spinning dope and subsequent fiber formation in a dry–wet-spinning process. The thus obtained precursor fibers were carbonized at different temperatures. In order to receive carbon fibers in high carbonization yields, the degree of substitution (DS) was adjusted. The rheological behavior of the spinning dope was studied and the spinning and carbonization parameters were optimized. Moreover, the precursor fiber tensile and structural properties were compared to pure cellulose fibers. According to thermal analysis coupled with evolved gas analysis (TGA-EGA) of the derivative and pure cellulose fibers, the carbonization yields could be almost doubled via the applied functionalization of cellulose and differences in the relative amounts of released gases during carbonization were studied. Both, precursor and carbon fibers were analyzed by, wide-angle X-ray scattering (WAXS), Raman spectroscopy, scanning electron microscopy (SEM), and tensile testing.

Hybrid polymer composites are the materials made by combining two or more different type of fibers in a matrix. Hybrid polymer composite material offers the designer to obtain the required properties in a controlled considerable extent by the choice of fibers and matrix. The properties are tailored in the material by selecting different kinds of fiber incorporated in the same resin matrix. They offer wide range of properties that cannot be obtained with a single type of reinforcement. Due to its high specific strengths, high specific modulus, low densities, light weight etc. based on its applications. Presently they are playing a vital role in aerospace, defence, transport, sport applications. Worldwide researches are keenly interested in finding out their behavior in real life exposed to various environmental conditions, variety of loads etc. In this paper, We fabricated carbon, e-glass and hybrid composites by using hand layup technique in uni-directional orientation with epoxy as a matrix material and conducted various tests such as tensile, compression on Universal Testing Machine (UTM) and hardness. The results are validated with FEA and observed that Al-6061-T6 which is used in manufacturing of military aircraft landing mats, truck bodies and frames etc. has a tensile strength of about 310.25Mpa.The tensile strength of hybrid fiber is 341Mpa which is higher than Al 6061-T6. We have compared the experimental results with ansys results and found that the experimental values are very close to the ansys results. But when compared within the fibers carbon fiber exhibited more strength when compared to other fibers

Power dissipation is expected to increase exponentially to 150-250 W per chip over the next decade. To manage this large heat output, it is necessary to minimize the thermal resistance between the chip and a heat dissipation unit that the device is attached to. It is therefore important to further improve the thermal performance of thermal interface materials (TIMs), which can be achieved through 1) improvement of the bulk thermal conductivity of TIMs; and/or 2) reduction of interfacial thermal resistances between the TIM and the device and/or TIM and the heat dissipation unit. The latter improvement may be obtained by enhanced physical properties of TIMs (e.g., viscosity or wetting ability) and/or surface modification of the heat dissipation unit or the inactive side of the device. Researchers have tried to take advantage of the high 1D thermal conductivities of graphite fibers, and more recently of carbon nanotubes (CNT), to reduce the thermal resistance between the chip and the heat dissipation unit. The efforts can be classified into three categories: 1) Forming pre-aligned graphite fiber or CNT films that have high bulk thermal conductivities in the heat transport direction, and applying such films as TIMs; 2) incorporating randomly oriented graphite fibers or CNT into silicone or epoxy matrices in the presence or absence of a second filler to improve bulk thermal conductivities, and applying the thus-formed blend as thermal greases, or adhesives or gels; and 3) growing CNT or graphite fibers from the heat sink/spreader surface and/or silicon backside and assembling them together with a TIM a to increase the bulk heat transport property and reduce the interfacial resistances, In this paper, we will present results for each of the three approaches, and discuss the challenges facing each one.

This study discusses about the spatial modelling to assess the total carbon stock and amount of Carbon-diOxide sequestrated by forest cover from atmosphere. The software ArcGIS were used to create a spatial model based on modelbuilder utility. The existing regression model and formulas were employed such as above ground biomass, tasselled cap transformation, brightness index, wetness index, below ground biomass, total accumulated biomass, total carbon stock and total carbon di oxide sequestered. These were integrated in model builder utility. Then output toolbox were utilised for further carbon footprint studies.

Hybrid polymer composites are the materials made by combining two or more
different type of fibers in a matrix. Hybrid polymer composite material offers the
designer to obtain the required properties in a controlled considerable extent by the
choice of fibers and matrix. The properties are tailored in the material by selecting
different kinds of fiber incorporated in the same resin matrix. They offer wide range of
properties that cannot be obtained with a single type of reinforcement. Due to its high
specific strengths, high specific modulus, low densities, light weight etc. based on its
applications. Presently they are playing a vital role in aerospace, defence, transport,
sport applications. Worldwide researches are keenly interested in finding out their
behavior in real life exposed to various environmental conditions, variety of loads etc.
In this paper, We fabricated carbon, e-glass and hybrid composites by using hand
layup technique in uni-directional orientation with epoxy as a matrix material and
conducted various tests such as tensile, compression on Universal Testing Machine
(UTM) and hardness. The results are validated with FEA and observed that Al-6061-
T6 which is used in manufacturing of military aircraft landing mats, truck bodies and
frames etc. has a tensile strength of about 310.25Mpa.The tensile strength of hybrid
fiber is 341Mpa which is higher than Al 6061-T6. We have compared the
experimental results with ansys results and found that the experimental values are
very close to the ansys results. But when compared within the fibers carbon fiber
exhibited more strength when compared to other fibers

Fiber-reinforced isolators not anchored to the structure represent a new development in seismic isolation. Their light weight, low cost and great ease of installation, in comparison with conventional elasto-meric isolators, could allow to extend the use of these valuable devices to seismic protection of housing and commercial buildings, particularly in developing countries. As demonstrated in studies available in the literature, fiber-reinforced isolators match the behavior of steel-reinforced ones. However the friction behavior between such new devices and the structure has not been investigated yet. This paper describes an experimental study on elastomeric isolators reinforced by bi-directional carbon fiber fabrics performed to investigate the static friction at contact surfaces. The isolators were placed in contact with concrete surfaces and subjected contemporaneously to compressive stress and shear strains. Friction behavior was analyzed in terms of isolator sliding with respect to the concrete sub-and superstructure. Influence on friction behavior of different parameters, such as level of compressive stress, rubber typol-ogy, concrete roughness, aging and loading rate, was investigated. The tests showed that, in relation to the value of the applied compressive stress, uncontrolled sliding of the isolator can occur by increasing the shear force. This unstable condition is called sliding instability herein. The experimental results are explained and the limit values of the compressive stress needed to avoid sliding instability is provided both for new and aged isolators, under quasi-static loading conditions. It is demonstrated that quasi-static tests are reasonably conservative with regard to safety. Patterns of stresses and relative displacements based on the experimental results are also proposed.

The research about the effect of carbon fiber on cobalt-60 teletherapy type GWXJ80 to the depth dose when gamma rays passed the carbon fiber couch and its effect to the surface dose has been conducted. Depth dose has been measured using ionization detector 0.65cc Extradin A12 model with the buildup cup that is connected to the electrometer Max4000 (Standard Imaging). Depth dose data have been obtained from 5 cm, 6 cm, 7 cm and 9 cm of depth with angle variations of each depth are from 0 o-360 o (10 o angle interval). The result of measurement has been processed using TRS398 protocol. The Surface dose measurement were performed using Gafchromic EBT2 film which was placed on the surface of slab phantom with and without carbon fiber. Irradiation field of this measurement were 6x6cm 2 , 8x8cm 2 , 10x10cm 2 , 12x12cm 2 , 14x14cm 2 , 16x16cm 2 and 18x18cm 2. The reading results of optic density using X-RITE densitometer were converted to dose refering the characteristic curve graph of Gafchromic EBT2 that had been prepared. Characteristic curve of the film have been made by giving 25cGy, 50cGy, 100cGy, 150cGy, 200cGy, 250cGy and 300cGy of dose to film strip in 2,5x3cm 2 of field. The result of this research showed that in 5cm, 6cm, 7cm, 8cm and 9cm of the depth, can be obtained transmission factors 0.954, 0.952, 0.951, 0.950 and 0.948. A great transmission factor change occured at the gantry angle position at 100 o to 120 o. Carbon fiber application for the surface dose increased the relative dose from 10.9% into 37.4% (6x6cm 2), 16.9% into 48.39% (8x8cm 2), 23.0% into 63.3% (10x10cm 2), 29.2% into 75.4% (12x12cm 2), 33.3% into 80.1% (14x14cm 2), 37% into 86.9% (16x16cm 2) and 43.3% into 91.2% (18x18cm 2).