Thermal diffusivity measurement of single fibers by an ac calorimetric method

Yamane, Tsuneyuki; Katayama, S.; Todoki, Minoru; Hatta, Ichiro

doi:10.1063/1.363394

Cited by 27 publications

(18 citation statements)

References 13 publications

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“…Equation (1) was used to predict composite thermal diffusivities ( c ) from t 1/2 values, which were obtained from LFA curves. Composite conductivity ( c ) and fiber thermal conductivity ( f ) was subsequently calculated using equations (2) to (4).…”

Section: Finite Element Modelingmentioning

confidence: 99%

Transient heat flow in unidirectional fiber–polymer composites during laser flash analysis: Experimental measurements and finite element modeling

Alway-Cooper

Theodore

Anderson

et al. 2012

Journal of Composite Materials

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Laser flash analysis (LFA), an unsteady-state technique originally developed for measuring the thermal diffusivity of homogenous materials, was used to estimate the thermal conductivity of carbon fibers consolidated in an epoxy matrix to form axially aligned unidirectional composites. Experimental studies were conducted for P-25 and K-1100 mesophase pitch-based carbon fibers whose conductivity values bracket almost two orders of magnitude ($10 and 1000 W/mÁK). Experimentally determined fiber thermal conductivity values were generally consistent with those cited in the literature after appropriate corrections were applied to account for the extremely high conductivity (low thermal resistance) of highly graphitic fibers, relative to the graphite coating. Finite element analysis was used to simulate heat flow patterns that may occur in a uniaxial fiber-polymer composite due to the large differences in the thermal conductivities of carbon fibers and polymer matrices. Simulations reveal that fiber thermal conductivity is accurately determined from composite response for high volume fraction of fibers (!0.6) regardless of fiber conductivity, or for lower conductivity fibers (10-100 W/mÁK) regardless of volume fractions. However, for composites containing high thermal conductivity fibers (100-1000 W/mÁK) at low volume fractions ( 0.2), fiber thermal conductivity may not be accurately determined due to transverse heat flow within the graphite layers that channel heat through the highly conductive fiber. Thus, under certain conditions, heat flow paths deviate from the one-dimensional heat flow assumption inherent to laser flash analysis and rule-of-mixtures.

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Section: Finite Element Modelingmentioning

confidence: 99%

Transient heat flow in unidirectional fiber–polymer composites during laser flash analysis: Experimental measurements and finite element modeling

Alway-Cooper

Theodore

Anderson

et al. 2012

Journal of Composite Materials

View full text Add to dashboard Cite

show abstract

“…For the thermal-conductivity measurement, Raman spectroscopy is a powerful technique, which is also applied to characterize the crystalline perfections [4]. For the thermal-diffusivity measurement, the alternating current calorimetric method [5], the Angstrom method [6], and some noncontact techniques have been applied [8,10]. Comparatively, reports on the specific heat of carbon fiber are limited.…”

Section: Introductionmentioning

confidence: 99%

“…Several techniques have been developed to measure the thermal conductivity and thermal diffusivity of carbon fiber [2,[4][5][6][7][8][9][10][11][12]. For the thermal-conductivity measurement, Raman spectroscopy is a powerful technique, which is also applied to characterize the crystalline perfections [4].…”

Section: Introductionmentioning

confidence: 99%

Simultaneous Measurements of Thermal Properties of Individual Carbon Fibers

et al. 2011

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Combining the steady-state and quasi-steady-state T type probes, the longitudinal thermal conductivity and thermal effusivity of individual mesophase pitchbased carbon fiber heat treated at 2800 • C and 1000 • C have been measured from 100 K to 300 K. The present method allows simultaneous measurements of thermal properties using the same instrument, by simply changing the applied direct current to alternating current. The specific heat is found to decrease with increasing heattreatment temperature and to approach the value of graphite. The highly graphitized carbon fiber has a maximum thermal conductivity of 410 W · m −1 · K −1 at about 250 K, and its thermal diffusivity decreases with increasing temperature. Comparatively, the thermal conductivity of the fiber heat treated at 1000 • C is much smaller, with the peak shifting to high temperature due to a large defect density, and its thermal diffusivity is nearly temperature independent.

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“…This drawback is avoided using modulated methods. Kawabata [6] and more recently Yamane et al [7] have used a periodic excitation from an halogen lamp, and a contact detection by thermocouple. The lamp is moved at different positions along the fiber.…”

Section: Measurement Methodsmentioning

confidence: 99%