The static field electrical conductivities of several discontinuous fiber composites are reported. Novel fabrication techniques are employed to produce systems of highly aligned and well-dispersed carbon fiber and coated carbon fibers. The thermal and breakdown properties of the matrix resin and breakdown behavior of the composites are examined. The distribution of orientations of the included phase is determined and recorded as an average orientation descriptor. Degree of fiber aggregation is found to be the principal determinant of bulk conductivity, eclipsing the effects of orientation and fiber fraction for the dilute concentrations investigated. A conductivity scale dependence is found for materials with tightly constrained microstructures.

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Ignition of LGP1846 (an aqueous mixture of ammonium and hydroxyl ammonium nitrates) was induced electrically in a laboratory cell to determine whether electrode damage from igniting arcs can be reduced by conditioning the propellant electrically immediately prior to ignition. The conditioning pro®les included DC and pulsing potentials from 40 to 900 volt over periods of 0.2 to 2 milliseconds prior to delivery of the initiating pulse. Analysis of pulse ignitions (no conditioning) indicate that a large sorption of energy was required with arc formation for the most reliable ignition behavior. Low potential currents were found to be limited by the propellant when using a small anodic electrode area. Reversing the polarity allowed larger conditioning charge¯ows, but the subsequent ignition energies were not found to be reduced in spite of this improvement. Conditioning was found to decrease the probability of vigorous reaction in some cases. Several electrode materials were studied; one composition was found to be superior in resistance to arc damage.