The electrical and thermal conductivity of woven pristine and intercalated graphite fiber–polymer composites

Abstract

A series of woven fabric laminar composite plates and narrow strips were fabricated from a variety of pitch-based pristine and bromine intercalated graphite fibers in an attempt to determine the influence of the weave on the electrical and thermal conduction. It was found generally that these materials can be treated as if they are homogeneous plates. The rule of mixtures describes the resistivity of the composite fairly well if it is realized that only the component of the fibers normal to the equipotential surface will conduct current. When the composite is narrow with respect to the fiber weave, however, there is a marked angular dependence of the resistance which was well modeled by assuming that the current follows only along the fibers (and not across them in a transverse direction), and that the contact resistance among the fibers in the composite is negligible. The thermal conductivity of composites made from less conductive fibers more closely followed the rule of mixtures than that of the high conductivity fibers, though this is thought to be an artifact of the measurement technique. Electrical and thermal anisotropy could be induced in a particular region of the structure by weaving together high and low conductivity fibers in different directions, though this must be done throughout all of the layers of the structure as interlaminar conduction precludes having only the top layer carry the anisotropy. The anisotropy in the thermal conductivity is considerably less than either that predicted by the rule of mixtures or the electrical resistivity.

Enhanced thermal conductivity of carbon fiber/phenolic resin composites by the introduction of carbon nanotubes

“…1 (f)), so that thermal conductivity measurements could be performed at room temperature using the Argon flash diffusivity testing procedure (Laser flash TC-7000, Ulvac-Riko Co.). 14,15 The thermal diffusion can be calculated using the following 4 equation α = 1.37L 2 / t 1/2 , where L is the thickness of the sample, t 1/2 is the time at which the rear surface of the sample reaches half of its maximum temperature, and α is the sample's thermal diffusivity. In addition, the density was also determined using the Sartorius technique (Genius).…”

A Novel Methodology for Macroscale, Thermal Characterization of Carbon Fiber-Reinforced Polymer for Integrated Aircraft Electrical Power Systems

“…The relatively high electrical and thermal conductivity of carbon fibre compared to resin results in UD CFRP having highly anisotropic thermal and electrical properties [2], [11], [12], [37]. If electrical current is injected into CFRP (for example, due to an electrical short circuit to ground), localised Joule heating occurs along sections where the fibre strands are conducting electrical current [2], [11], [38]. Existing aerospace industry standards do not allow the intentional conduction of electrical current through CFRP on aircraft [39], due to the relatively high electrical resistance of CFRP compared to metals.…”

Porous materials for direct and indirect evaporative cooling in buildings

“…Figure 17.10 shows the structure of a hardwood fibre, and Table 17.2 presents the thermal conductivity of various fibrous materials [22]- [25]. It can be seen that the fibres have much lower thermal conductivity than metals, ranging from 0.01 to 0.3 W/m·K [26]. Solid fibres have lower thermal conductivity than porous ones [25].…”