Electrical and Thermal Properties of Composite of Composite of Liquid Crystalline Polymer Filled with with Carbon Black

摘要

The electrical resistivity and thermal conductivity of a liquid crystalline polymer (LCP) filled with a commercial carbon black (CB) of various volume fractions (#PHI#) is investigated. The percolation threshold (#PHI#_c) is found at about 3%, and the resistivity (p) as a function of (#PHI#-#PHI#_c) satisfies the exponential function. Although the pure LCP is highly anisotropic in thermal and mechanical properties after processing, the composite samples exhibit no preferential direction for electrical conduction. Samples of #PHI# below #PHI#-c exhibit a negative temperature coefficient of resistivity while those above #PHI#_c show almost no temperature dependence form room temperature to 200 deg C. In addition, the samples at lower #PHI# have higher thermal condictivity in the LCP flow direction than those measured in the transverse and thickness directions, and they approach the same value at higher #PHI#. This result indicates that preferential molecular alignment of the matrix LCP is responsible for the behavior of the thermal conductivity of the composites.