Viscoelastic and conductive characteristics of titanium carbide/polyethylene composites in relation to their structural parameters

Titanium carbide (TiC)/polyethylene (PE) composite is a candidate for a positive-temperature coefficient resistor, which is used for a self-recoverable element that provides protection from overcurrents in many kinds of electrical devices. In the present study, the PE-based composites containing various volume fractions (ϕ) of TiC were prepared, after which their viscoelastic characteristics were investigated compared against their electric conductivity as a function of temperature. When the value of ϕ exceeded 0.39, the resistivities of the sample decreased steeply with increasing TiC content. The resistivity of the specimen maintained a constant value of about 0.1 Ωcm in the range of ϕ values > 0.52. Alternatively, the changes in the storage moduli at room temperature with various ϕ values of the samples could be expressed by a modified Kerner equation with the maximum ϕ value of 0.67. Melting behaviors of the samples were also examined and discussed in terms of their morphological features. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 91: 3134–3139, 2004