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

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 (<i>T</i>_s) by self-heating (Joule heat). The composite was cut when <i>T</i>_s was beyond 108 °C. On the other hand, the measurement of the composite with 4 vol % beyond 88 °C was impossible, since <i>T</i>_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

Appearance of Perfect Amorphous Linear Bulk Polyethylene under Applied Electric Field and the Analysis by Radial Distribution Function and Direct Tunneling Effect

Without melting flow, linear ultrahigh molecular weight polyethylene (UHMWPE) provided X-ray intensity curve from only amorphous halo at 129.0 °C (surface temperature, <i>T</i>_s arisen by Joule heat) lower than the conventionally known melting point 145.5 °C on applying electric field to UHMWPE-nickel-coated carbon fiber (NiCF) composite. Such surprising phenomenon was analyzed by simultaneous measurements of X-ray intensity, electric current, and <i>T</i>_s as a function of time. The calculated radial distribution function revealed the amorphous structure with disordered chain arrangement. The appearance of such amorphous phase was arisen by the phenomenon that the transferring electrons between overlapped adjacent NiCFs by tunneling effect struck together with X-ray photons and some of the transferring electron flown out from the gap to UHMWPE matrix collided against carbon atoms of UHMWPE. The impact by the collision caused disordering chain arrangement in crystal grains

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

A composite with both high permittivity and high elasticity was prepared by using copper phthalocyanine (CuPc) and polyurethane (PU) foam. The formation and chemical, structural, and electrical characterizations of CuPc and the PU/CuPc composites were described, and a variety of analytical methods were proposed to examine the structure and the morphology of the specimens. The electrical characterization of the specimens was performed for a molded CuPc film and the PU/CuPc composite in the frequency range from 0.1 Hz to 1 MHz. The frequency dependencies of impedance (<i>Z</i>*), permittivity (ε*), and electrical modulus (<i>M</i>*) were analyzed by combinational models of circuits. The effects of the enhanced dielectric properties of the composite at 0.1 Hz indicating predominance of the dc component were evaluated by the tunneling effect theoretically. The electric energy evaluated as a function of pressure suggested that the PU/CuPc composite foam is a promising material with successful conversion from natural mechanical energy to electric energy