Carbon fiber reinforced carbon matrix composites(C/C)are popular due to their excellent mechanical and conductive properties,while their dielectric behavior has received little attention.The LCR meter was used to measure the relative permittivity of C/C.The resistivity was measured by current source and nano-voltage meter combined with four-probe method.The results show that the fractional change in relative permittivity per unit strain is 528±8,which is 375％higher than the fractional change in resistivity per unit strain,indicating that the dielectric behavior is more sensitive to changes in microstructures.In addition,the enhancement of dielectric behavior of C/C is due to compressive strain inducing micro defects,such as grain boundaries,interfaces,etc.,that provide sites for space polarization involving a fraction of electrons and holes;on the other hand,the polarization continuity of C/C is enhanced by compression.The increase in the number of electrons and holes that participate in polarization per unit compressive strain is(1.37±0.02)x 1010.The relative permittivity of C/C is lower than both carbon fiber and graphite due to high porosity and interfaces.
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