Structure–property relationships for high thermal conductivity carbon fibers

AbstractThe remarkable electrical and thermal conductivities of isolated carbon nanotubes have spurred worldwide interest in using nanotubes to enhance polymer properties. Electrical conductivity in nanotube/polymer composites is well described by percolation, where the presence of an interconnected nanotube network corresponds to a dramatic increase in electrical conductivity ranging from 10−5 S/cm to 1 S/cm. Given the high aspect ratios and small diameters of carbon nanotubes, percolation thresholds are often reported below 1 wt% although nanotube dispersion and alignment strongly influence this value. Increases in thermal conductivity are modest (∼3 times) because the inter facial thermal re sis tance between nanotubes is considerable and the thermal conductivity of nanotubes is only 104 greater than the polymer, which forces the matrix to contribute more toward the composite thermal conductivity, as compared to the contrast in electrical conductivity, >1014. The nanotube network is also valuable for improving flame-retardant efficiency by producing a protective nanotube residue. In this ar ticle, we highlight published research results that elucidate fundamental structure–property relationships pertaining to electrical, thermal, and/or flammability properties in numerous nanotube-containing polymer composites, so that specific applications can be targeted for future commercial success.

Download Full-text

The Thermal Transport Properties of Polymers

Rubber Chemistry and Technology ◽

10.5254/1.3535156 ◽

1977 ◽

Vol 50 (3) ◽

pp. 480-522 ◽

Cited By ~ 52

Author(s):

D. Hands

Keyword(s):

Thermal Conductivity ◽

Thermal Diffusivity ◽

Heat Flow ◽

Natural Rubber ◽

Material Selection ◽

Reliable Data ◽

Large Scatter ◽

Structure Property ◽

Structure Property Relationships

Abstract Values of thermal diffusivity and thermal conductivity are needed for heat-flow calculations, for the determination of structure-property relationships, and for material selection and comparison. However, all aspects are hampered by a dearth of reliable data and anything more than a superficial glance at the literature is apt to be discouraging for the uninitiated. Hardly any thermal diffusivity data exist, and the reported values of thermal conductivity show very large scatter. The present state of confusion can be seen, for example, in Figures 1 and 2, which show the reported thermal conductivity values for polystyrene and gum natural rubber. Not only do the values differ at some temperatures by more than 100%, and in the case of rubber by almost 300%, but different trends are indicated throughout the temperature range. Discrepancies of this size cannot be due to sample variations, and they give some indication of the experimental difficulties associated with thermal property measurements.

Download Full-text

Characterization of high thermal conductivity carbon fibers and a self-reinforced graphite panel

Carbon ◽

10.1016/s0008-6223(97)00189-9 ◽

1998 ◽

Vol 36 (3) ◽

pp. 233-245 ◽

Cited By ~ 82

Author(s):

P.M. Adams ◽

H.A. Katzman ◽

G.S. Rellick ◽

G.W. Stupian

Keyword(s):

Thermal Conductivity ◽

Carbon Fibers ◽

High Thermal Conductivity

Download Full-text

Kraft lignin as feedstock for chemical products: The effects of membrane filtration

Holzforschung ◽

10.1515/hf.2009.049 ◽

2009 ◽

Vol 63 (3) ◽

Cited By ~ 64

Author(s):

Ida Brodin ◽

Elisabeth Sjöholm ◽

Göran Gellerstedt

Keyword(s):

Molecular Mass ◽

Carbon Fibers ◽

Membrane Filtration ◽

Molecular Mass Distribution ◽

Ceramic Membranes ◽

Kraft Pulping ◽

Structure Property ◽

Structure Property Relationships ◽

Chemical Products ◽

Technical Lignins

Abstract The use of technical lignins as feedstock for chemical products will require improvements in purity, molecular mass distribution, and thermal behavior. Therefore, industrial black liquors from kraft pulping of softwood (spruce/pine) and hardwood (birch and Eucalyptus globulus) have been subjected to fractionation according to molecular mass by ceramic membranes. After acidification and isolation of the lignin fractions, a variety of analytical methods have been applied to help understand their structure – property relationships. From all types of lignin, the chemical and polymeric properties of fractions isolated from the membrane permeates were more homogeneous. This demonstrates that technical kraft lignins, irrespective of origin, may constitute an interesting feedstock for products, such as carbon fibers, adhesives, and phenol-based polymers.

Download Full-text

Synthesis of Copper/Silicon-Carbide Composites in a Thermodynamic Disequilibrium

Materials Science Forum ◽

10.4028/www.scientific.net/msf.825-826.189 ◽

2015 ◽

Vol 825-826 ◽

pp. 189-196 ◽

Cited By ~ 1

Author(s):

Maren Klement ◽

Alwin Nagel ◽

Oliver Lott

Keyword(s):

Thermal Conductivity ◽

Silicon Carbide ◽

Thermal Expansion ◽

Coefficient Of Thermal Expansion ◽

Quantitative Description ◽

Casting Process ◽

Heat Sinks ◽

High Thermal Conductivity ◽

Structure Property ◽

Mechanical Loads

Composites with interpenetrating metal-ceramic microstructures (IPC, interpenetrating composites) can be tailored for specific applications, such as high thermal conductivity combined with low thermal expansion, e.g. for heat sinks. Heat sinks are required in power electronic devices or in future fusion reactor technology where extreme conditions and high cyclic thermo-mechanical loads appear. Due to its rigid ceramic backbone IPCs are expected to reveal high thermal stability. Pure silicon carbide exhibits high thermal conductivity, low coefficient of thermal expansion, high corrosion and wear resistance. But it is also known as a very brittle material when mechanical loads are applied. Thus a composite of silicon carbide with ductile and highly conductive copper seems to be a promising new material for a number of applications.This paper reports the synthesis of Cu-SiC composites using a unique high temperature squeeze casting process (HTSC). Microstructural design of SiC-preforms with open porosity and its synthesis progress is reported. Influence of preform properties, temperature, pressure and atmosphere during HTSC were investigated. A qualitative and quantitative description of the microstructure of the composites and their composition allows the creation of structure-property correlations that take effect retroactively to the casting process.

Download Full-text