Effect of moisture on the interlaminar interface of a carbon fiber polymer-matrix composite, studied by contact electrical resistivity measurement

Moisture was found to have a reversible effect on the interlaminar interface of a continuous carbon fiber epoxy-matrix composite. An increase in humidity increased the resistivity. The reversibility was essentially complete after the first cycle of humidity variation. The effect is attributed to expansion of the matrix at the interlaminar interface due to moisture uptake. It allows use of the composite for humidity sensing.