Considerable Different Frequency Dependence of Dynamic Tensile Modulus between Self-Heating (Joule Heat) and External Heating for Polymer–Nickel-Coated Carbon Fiber Composites

Abstract

Dynamic tensile moduli of polyethylene--nickel-coated carbon fiber (NiCF) composites with 10 and 4 vol % NiCF contents under electrical field were measured by a homemade instrument in the frequency range of 100--0.01 Hz. The drastic descent of the storage modulus of the composite with 10 vol % was verified in lower frequency range with elevating surface temperature (T(s)) by self-heating (Joule heat). The composite was cut when T(s) was beyond 108 °C. On the other hand, the measurement of the composite with 4 vol % beyond 88 °C was impossible, since T(s) did not elevate because of the disruption of current networks. Incidentally, the dynamic tensile moduli by external heating could be measured up to 130 and 115 °C for 10 and 4 vol %, respectively, but the two composites could be elongated beyond the above temperatures. Such different properties were analyzed in terms of crystal dispersions, electrical treeing, and thermal fluctuation-induced tunneling effect.

Dielectric Change of Copper Phthalocyanine and Polyurethane Foam with High Elasticity as a Function of Pressure Discussed in Terms of Conversion from Natural Mechanical Energy to Electric Energy

“…D is the average gap distance between overlapped adjacent CuPc (see Figure c), and e denotes the electron charge (which equals 1.602 × 10 –12 erg). ∑ 0 (ε T ) and ∑ 1 (ε T ) are formulated as differential tunneling current by ε T . − δ̅ 0 (= δ̅/ε) and U 0 are parameters to form nonparabolic potential function as follows: U ( u , ε ) = U 0 [ 1 − λ u false( 1 − u false) − δ̅ 0 ε u ] where u = x / D is the reduced spatial variable, in which x is the distance from the left surface of the junction and U 0 is height of the rectangular potential barrier in the absence of an image-force correction. λ, which is given by 0.795 e 2 /4 DKU 0 ( K : permittivity of insulating barrier = 1 for air), is an important dimensionless parameter.…”

“…The parameter χ = (8π 2 mU 0 / h 2 ) ( h : Planck constant) is the tunneling constant and φ(ε T ) in eq given by ξ(ε T )/ξ(0) has the property that φ(0) = 1 and φ(1) = 0. The complicated derivation of ξ(ε T ) was described elsewhere − to determine the barrier distance D and area A . The calculation was done at room temperature ( T = 20 °C).…”

“…As for λ, the same value obtained is probably thought to be due to the low applied voltage like 1 V. A question arises why the area A is too small in comparison with the resultant contact area by the disruption of foams by pressure. This means that the asperity of CuPc grain surfaces constricts the whole approximation between CuPc surface by foam disruption, and some contact areas (see Figure c) within large collapsed area play an important role to induce tunneling effect by the approximation to satisfy desire potential barrier. − …”

Application and Research on Carbon Fiber Composite Materials

“…Excellent resistance to corrosion and radiation. R. Zhang and his colleagues measured the dynamic tensile moduli of polyethylene-nickel-coated carbon fiber composites with 10 and 4 vol % NiCF contents under electrical field by a homemade instrument in the frequency range of 100-0.01 Hz [3]. The drastic descent of the storage modulus of the composite with 10 vol % was verified in lower frequency range with elevating surface International Conference on Mechatronics, Electronic, Industrial and Control Engineering (MEIC 2015) temperature by self-heating (Joule heat).…”

“…The composite was cut when surface temperature was beyond 108 °C. On the other hand, the measurement of the composite with 4 vol % beyond 88 °C was impossible, since sufer temperature did not elevate because of the disruption of current networks [3].…”