BS ISO 1419:2016 pdf download – Rubber- or plastics-coated fabrics — Accelerated-ageing tests
4 Method A: Loss of volatiles on heating of plasticized-PVC-coated fabrics 4.1 General As a result of natural ageing, PVC-coated fabrics may lose plasticizer by volatilization, and in time this will have an adverse effect on the performance of the coating. The extent to which a particular material will be so affected will depend on the formulation of the coating, so it is desirable to assess this property. The method described is designed to accelerate the loss of volatiles by exposing test pieces to an elevated temperature, followed by determination of the loss in mass of the coating. The procedure shall be in conformance with ISO 188.
4.2.1 Air Oven – It shall have slow circulation of air, providing not less than three and not more than ten air changes per hour. It shall have provisions for controlling and measuring the rate of airflow and for maintaining and measuring the desired temperature and relative humidity, if necessary. There shall be provisions for suspending the test pieces vertically within the oven. During the ageing process, in order to prevent individual test pieces touching each other or the inner walls of the oven and being exposed to higher temperature, the test pieces shall not be within 10 mm of each other or within 50 mm of the inner surfaces of the oven, The incoming air shall be at the temperature specified before coming into contact with the test pieces. Any electric elements used for heating the incoming air shall be shielded to avoid direct radiation on to the test pieces. No copper or copper alloy shall be within the ageing chamber of the oven. The oven shall be of such a size that the total volume of the test pieces does not exceed 10 % of the free air space in the oven. Means shall be provided for suspending the test pieces vertically within the oven so that they are not within 10 mm of each other or within 50 mm of the inner surfaces of the oven.
The temperature of the oven shall be maintained at 100°C with an accuracy of ±1 °C.
4.2.2 Thermometer, or other temperature-indicating device, for monitoring the oven temperature with an accuracy of ±1 °C.
4.2.3 Balance, capable of weighing to an accuracy of 1 mg.
4.2.4 Ruler or other length-measuring device, of accuracy ±0,5 mm.
4.2.5 Desiccator for cooling the specimens after removal from the oven.
4.3 Preparation of test pieces
Cut out six test pieces, each measuring 100 cm 2 ± 1 cm 2 , selected so that, as far as possible, they are evenly spaced across the Sample, but not within 50 mm of a selvedge.
4.4 Conditioning and determination of mass
Condition the test pieces in atmosphere A, B or C as defined in ISO 2231. Determine and record the mass m 1 of each test piece to an accuracy of 1 mg in accordance with ISO 2286-1. Determine the mass per unit area Q AC of the coating of three test pieces in accordance with ISO 2286-2.
4.5 Procedure Select three of the conditioned test pieces, making a note of the conditioned mass of each. Pre-heat the oven to the test temperature of 100 °C ± 1 °C. Place the test pieces in the oven so that they are free from strain and exposed to the free passage of air on both sides. Remove the test pieces from the oven after 16 h and allow to cool. Re-condition the test pieces in accordance with 3.4 and determine and record the mass m 2 of each to an accuracy of 1 mg in accordance with ISO 2286-2.
NOTE If test pieces conditioned as specified in 3.4 after preparation approach equilibrium from the wet side of the hysteresis curve, this may result in an apparent inaccuracy due to the hysteresis loss caused by re- conditioning from the dry side of the hysteresis curve after ageing. This effect will be more marked with highly hygroscopic substrates, and in such cases it is advisable to pre-condition the test pieces in a dry atmosphere, i.e. one having a relative humidity less than 10 %, prior to conditioning as specified in 3.4.