ISO 9073-4-2021 pdf free download – Nonwovens — Test methods — Determination of tear resistance by the trapezoid procedure.
4Principle
Marking of a trapezoid on a test specimen.Clamping of the non-parallel sides of the trapezoid in the jawsof a tensile testing machine.Application of a continuously increasing extension to the test specimenin such a way that a tear propagates across its width. The force to continue the tear over a specifieddistance is recorded.The arithmetic mean of the maximum force of specimens is taken as the result oftesting.
5 Apparatus
5.1 Tensile testing machine, metrological confirmation system of which shall be in accordance withISO 10012.The constant rate of extension testing machine (CRE testing machine) having the followingcharacteristics:
a)capable of operating at a constant rate of extension of (100 ± 10) mm/min;b)capable of gauge length to be set to (25± 1) mm;
c) provided with means for recording the force applied to the test specimen during the tear test;d) under conditions of use, accuracy of the apparatus shall be class 1 of lSO 7500-1.The error of the
indicated or recorded maximum force at any point in the range in which the machine is used shallnot exceed ± 1 %,and the error of the indicated or recorded jaw separation shall not exceed ± 1 mm;e) if recording of force and extension is obtained by means of data acquisition boards and software,
the frequency of data collection shall be at least 8 per second.
lf a class 2 tensile testing machine according to ISO 7500-1 is to be used, this shall be stated in thetest report.
NOTE_ Constant rate of traverse type (CRT) tester can also be used when agreed upon between interestedparties.There can be no overall correlation between the test results obtained with the CRT-type machine andCRE-type machine.
5.2 Clamping device, comprising the two jaws of the machine, the central points of which are in theline of applied force, the front edges at right angles to the line of applied force and the clamping faces inthe same plane. The jaws shall be capable of holding the test specimen without allowing it to slip anddesigned so that they do not cut or otherwise weaken the test specimen. The width of the jaws shouldpreferably be 100 mm, but shall not be less than the width of the test specimen.
5.3 Isosceles trapezoid template, having dimensions with a tolerance of±0,5 % as shown in Figure1.5.4 Equipment, in which test specimens can be immersed in water preparatory to wet testing.
5.5Grade 3 water, in accordance with ISo 3696 for wetting test specimens.
5.6Nonionic wetting agent.
6Sampling
Carry out sampling in accordance with ISO 186, ensuring that the areas from which the specimens aretaken have no visible flaws and are not creased.
7 Preparation and conditioning of test specimens
7.1Unless otherwise specified, cut five test specimens in the machine direction and five in the cross-machine direction.
NOTE The edge of the sample cannot normally form part of the test specimen
7.2 Cut test specimens (75 ± 1) mm x (150 ± 2) mm. Mark each test specimen with an isoscelestrapezoid using the template (5.3).Make a preliminary cut of 15 mm in the centre of the trapezoid shortside as shown in Figure 2.
NOTE Other dimensions, respecting the general proportions of the original test specimen, can be agreedbetween interested parties, especially in order to reproduce some in-use conditions of nonwovens, and can benoted in the test report.T’he values measured with different test specimen dimensions cannot be compared.ISO 9073-4 pdf download.