AATCC 84 pdf free download
AATCC 84 pdf free download.Electrical Resistance of Yarns.
4.2 The safety recommendations provided by the manufacturer of the radioactive bar should be followed.
4.3 The radioactive bar emits alpha radiation which is externally harmless to the human body. The radioactive isotope polonium 210 is toxic and precaution should be exercised to prevent ingestion or inhalation of the solid material. Do not take the radioactive bar apart or touch the radioactive strip under the grid. If the strip is touched or handled, wash hands thoroughly at once. Return the device to the manufacturer when it loses its elTectiveness as a static eliminator or for disposal if use is to be discontinued. Do not discard as scrap.
5. Apparatus and Materials
5.1 Electrical resistance meter equipped with either fixed position parallel plate electrodes or with separate variable position parallel plate electrodes (sec 11.1). The concentric ring electrode system recommended for fabrics in AATCC Method 76 is not suitable ft)r use in testing yams.
5.2 Conditioning and test chamber (see
11.2).
5.3 Standard resistors (see 11.3).
5.4 Radioactive bar (see 11.4).
6. Test Specimens
6.1 The length of the test specimens depends on whether or not the electrodes used are in fixed or variable position. If the electrode system used provides for variable distances between the parallel plates, run a preliminary test to determine what distance between the plates provides the greatest sensitivity for resistance measurements for the meter being used.
6.2 To determine the uniformity of resistance along a single end of yam, make measurements on at least 10 specimens of single strands.
6.3 For predicting the properties of woven or knitted fabrics to be made from yarn tested by this method, measurements should be made on multiple strands.
6.4 Prepare a minimum of three test specimens for each test, with parallel strands having the same tension, evenly spaced, with no overlap or touching along their length. When a limited supply of yam is available, each specimen should contain 10 strands. If an adequate supply of yarn is available, prepare larger specimens by winding 50-100 turns on a skein winder, then fastening the strands with adhesive tape to prepare lengths suitable fbr the electrode system used. The number of strands in the specimen must be the same for each test specimen for reproducible results. The resistance may also be dependent on the cross-section of the yarn bundle; thus, similarly manufactured fibers may yield yams with different resistance, due to different numbers of filaments in the yam bundle or different numbers of plies.
7. Procedure
7.1 Calibrate the electrical resistance meter according to the manufacturer’s recommendations (see 11.3).
7.2 Condition the test specimens in a suitable testing chamber or conditioning room at the pre-selected relative humidity and temperature at which the electrical resistance of the yarn is to be measured.
7.2.1 For yams which require antistatic treatments or whose electrostatic propensity is critical, measurements at 20% RI-I will be most meaningful. For special requirements other relative humidities may be used. For example, preconditioning at 21 ± 2°C is required for antistatic sheeting, film and textiles for use in hospital operating rooms (see 11 .2.1). If it is necessary to measure electrical resistance under a broad range of conditions, additional tests may be run at 65% RI-I and at 24°C or other relevant conditions.
7.2.2 Condition the specimens at 24°C and at the predetermined relative humidity for a minimum of 4 h or until equilibrium is attained. A sufficient indication of equilibrium is no significant change of resistance on further conditioning. A significant change may be considered ± 5% of the logarithm of the resistance (Log R).AATCC 84 pdf download.
