The Features of Electric Charge Decay in the Polyester Fabric Containing Metal Fibres

Abstract

The aim of the research was to reveal the features of electrical charging and dissipation of charges in the polyester fabric containing metal fibres. The woven fabrics for protective clothing to avoid incendiary discharges were manufactured in Lithuanian Textile Institute for the study. Warp threads of the fabrics were of polyester (PES) 8.4 tex (f 72) yarns. PES/INOX 20 tex union yarn (80 % : 20 %) was taken as a thread containing metal fibres. INOX is known as stainless that contains at least 10.5 % of chromium. This conductive yarn was inserted in the fabrics in three different variants: 1) 25 picks PES + 1 pick PES/INOX; 2) 49 picks PES + 1 pick PES/INOX; 3) 71 picks PES + 1 pick PES/INOX. The fabric with only the PES picks was used as control fabric. Vertical electrical resistance (R), surface resistivity (ρ), half decay time (t50) of electric field strength and shielding factor (S) values were determined according to EN 1149 series standards for the fabrics as received and for those after 5 washing cycles (40 ºC). It is shown that vertical electrical resistance and surface resistivity are the parameters which values are very sensitive to quantity of conductive PES/INOX yarns in the fabrics. Half decay time and shielding factor also depend on the distance between the yarns with metal fibres. Although washing of fabrics impairs electrostatic properties, fabrics with the shortest distances between PES/INOX yarns have the best shielding effect and can be used in working clothing to prevent the static charges build-up.