A modification of the proposed ASTM Test Method for Evaluating Triboelectric (Static) Charge Generation on Protective Clothing Materials (F23.20.05) procedure has been developed to measure peak potentials and energies from a capacitor, as well as peak potentials and decay rates from specimen surfaces charged by triboelectrification. The test system simulates a clothed human body rubbing an insulated surface and touching a grounded object, generating a spark of several thousand volts.
Experiments following both the proposed ASTM method and its modification were conducted at both 0% and 20% relative humidity (RH) and room temperature. Several one- and two-layer fabric systems were tested, including combinations of aramid/PBI, aramid/carbon, aramid/FR viscose, non-FR cotton and FR cotton.
Data from both tests were regressed with peak potentials obtained during human-body experiments. At 0% RH, regression coefficients (R2) were 0.85 and 0.28 for peak potentials and charge decays from fabric surface (proposed ASTM F23.20.05), respectively. For peak potentials and energies (modified version), R2 were 0.92 and 0.86, respectively. At 20% RH, R2 were 0.86 and 0.34 for peak potentials and charge decays (proposed ASTM), respectively, and 0.94 and 0.87 for peak potentials and energies (modified ASTM), respectively. Thus, it seems that measuring the peak potentials and energies from charged fabric systems using the new device and procedure can be considered sufficient to predict with high accuracy the static propensity of protective clothing systems in real-life conditions.