Pitch-matrix composites for electrical, electromagnetic and strain-sensing applications

Pitch-matrix composites for deicing, electromagnetic shielding and strain sensing have been developed by using carbon fiber (discontinuous) and carbon black as electrically conductive fillers. A composite with carbon fiber (5 vol%) as the sole filler is effective for strain sensing, which functions by the electrical resistivity increasing reversibly with tensile strain. A composite with carbon fiber (3.4 vol%) and carbon black (1.5 vol%) is less effective for strain sensing and is lower in tensile strength, modulus and ductility, but it is lower in the electrical resistivity. A composite with carbon black (7 vol%) as the sole filler is very high in resistivity, but exhibits high storage modulus. Either carbon fiber or carbon black as filler increases the storage modulus, decreases the resistivity, renders the ability to provide EMI shielding and increases the softening temperature.