Electrical resistivity studies on acid-treated E-glass fabric

E-glass fabrics were soaked in 0.1 to 2N hydrochloric acid for 0.5 to 3 h to remove the non-siliceous ions, and the volume resistivity of the treated fabrics was measured using d.c. voltages of 100, 250, 400 and 500. The electrical resistivity of the treated fabric increased sharply with increase in normality from 0.5N to 1.0N for a constant soaking time of 3 h; further increase was marginal at higher normalities (above 1.0N). A sharp increase in the electrical resistivity of the fabric was also found in the initial 1/2 h of soaking when fabrics were soaked in constant normality acid (2N) and resistivity was measured with time. The initial sharp increase in the electrical resistivity was attributed to the bulk removal of Na2O + K2O ions which are the main contributors to the conductivity. The removal of bivalent and trivalent ions did not contribute much to the increase in the electrical resistivity at this stage. The electrical resistivity of the treated fabrics increased with increase in the post heat-treatment temperature. During acid treatment, the non-siliceous ions are removed, which makes the fabric porous and susceptible to water absorption. Owing to absorption of moisture, the electrical resistivity of the fabric decreases with time and reaches a constant minimum value. The rate of decrease in electrical resistivity decreases with increase in the normality of the soaking acid. The constant minimum value of electrical resistivity increases with increase in post heat-treatment temperature for a fabric soaked in a constant normality acid. The mechanism of electrical conduction in the acid-treated fabrics after absorption of water is attributed to the proton movement which occurs by the polarization of the diffused water to the interior of the structure.