Electrical and thermal properties of composite of liquid crystalline polymer filled with carbon black

• Published in: Journal of applied polymer science Vol. 82; no. 6; pp. 1549 - 1555
• Main Authors: Wong, Y. W., Lo, K. L., Shin, F. G.
• Format: Journal Article
• Language: English
• Published: New York John Wiley & Sons, Inc 07.11.2001; Wiley
• Subjects: anisotropic properties; Applied sciences; carbon black; Composites; electrical resistivity; Exact sciences and technology; Forms of application and semi-finished materials; liquid crystalline polymer; Polymer industry, paints, wood; Technology of polymers; thermal conductivity; Carbon black; Electrical properties; Volume fraction; Resistivity; Thermotropic state; Temperature effect; Benzoate(hydroxy) copolymer; Dispersion reinforced material; Experimental study; Composite material; Molecular orientation; Anisotropy; Liquid crystal polymers; Optical properties; Preparation; Thermal conductivity; Oriented copolymer
• ISSN: 0021-8995; 1097-4628
• DOI: 10.1002/app.1993

The electrical resistivity and thermal conductivity of a liquid crystalline polymer (LCP) filled with a commercial carbon black (CB) of various volume fractions (ϕ) is investigated. The percolation threshold (ϕc) is found at about 3%, and the resistivity (ρ) as a function of (ϕ − ϕc) 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 ϕ below ϕc exhibit a negative temperature coefficient of resistivity while those above ϕc show almost no temperature dependence from room temperature to 200°C. In addition, the samples at lower ϕ have higher thermal conductivity in the LCP flow direction than those measured in the transverse and thickness directions, and they approach the same value at higher ϕ. This result indicates that preferential molecular alignment of the matrix LCP is responsible for the behavior of the thermal conductivity of the composites. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 1549–1555, 2001