BS EN ISO 9073-4:2021 pdf free.Nonwovens – Test methods Part 4: Determination of tear resistance by the trapezoid procedure.
Marking of a trapezoid on a test specimen. Clamping of the non-parallel sides of the trapezoid in the jaws of a tensile testing machine. Application of a continuously increasing extension to the test specimen in such a way that a tear propagates across its width. The force to continue the tear over a specified distance is recorded. The arithmetic mean of the maximum force of specimens is taken as the result of testing.
5 Apparatus
5.1 Tensile testing machine, metrological confirmation system of which shall be in accordance with ISO 100 12.The constant rate of extension testing machine (CRE testing machine) having the following characteristics:
a) capable of operating at a constant rate of extension of (100 ± 10) mm/mm;
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 ISO 7500-1. The error of the indicated or recorded maximum force at any point in the range in which the machine is used shall not 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.
If a class 2 tensile testing machine according to ISO 7500-1 is to be used, this shall be stated in the test report.
NOTE Constant rate of traverse type (CRT) tester can also be used when agreed upon between interested parties. There can be no overall correlation between the test results obtained with the CRT-type machine and CRE-type machine.
5.2 ClampIng device, comprising the two jaws of the machine, the central points of which are in the line of applied force, the front edges at right angles to the line of applied force and the clamping faces in the same plane. The jaws shall be capable of holding the test specimen without allowing it to slip and designed so that they do not cut or otherwise weaken the test specimen. The width of the jaws should preferably 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 Figure 1.
5.4 Equipment, in which test specimens can he immersed in water preparatory to wet testing.
5.5 Grade 3 water, in accordance with ISO 3696 for wetting test specimens.
5.6 Nonionic wetting agent.
6 Sampling Carry out sampling in accordance with ISO 186, ensuring that the areas from which the specimens are taken have no visible flaws and are not creased.
7 Preparation and conditioning of test specimens
7.1 Unless 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 isosceles trapezoid using the template (). Make a preliminary cut of 15 mm in the centre of the trapezoid short side as shown in Figure 2.
NOTE Other dimensions, respecting the general proportions of the original Lest specimen, can be agreed between interested parties, especially in order to reproduce some in-use conditions of nonwovens, and can be noted In the test report. The values measured with different test specimen dimensions cannot be compared.
7.3 Condition the test specimens in the standard atmosphere as specified in ISO 139.
The test specimens do not need to be conditioned when the tear force is measured in wet state.It is recommended that test specimens be conditioned for at least 24 h in relaxed state.
7.4 If the tear force of test specimens in wet state is required, immerse the test specimens for a period of one hour in grade 3 water (5.5) at a temperature of 20 °C ± 2 °C. For specimens not readily wet out with water, such as those treated with water-repellent or water-resistant materials, an aqueous solution containing not more than I g of a nonionic wetting agent per litre may be used instead of water.
NOTE For tropical regions, temperature according to ISO 139 can be applied.
8 Procedure
8.1 Carry out the test in the standard atmosphere for testing (see ISO 139).
8.2 At the start of the test, set the gauge length of tensile-testing machine to (25 ± 1) mm and set the rate of extension to 100 mm/mm. Select the force range of the testing machine so that the break occurs between 15 % and 85 % of full scale.
8.3 Secure the test specimen in the machine, clamping along the non-parallel sides ol the trapezoid with the cut halfway between the clamps. Hold the short edge taut and let the long edge lie in folds.
8.4 Start the machine and record the tearing force on the recording device.
8.5 The tearing force will be a single value or appear as a series of maxima and minima. Two typical tearing curves are as shown in Eigur3.
8.6 If the test specimen does not tear at the cut or the specimen slides out from the clip, no result shall be registered. The specimen should be cut again on the original sample to obtain five normal results for each direction.
NOTE For specimens with strong tear force or easy to slip, special pincers can be replaced or pincers holding surface can be added with liner material. which can be explained in the test report.
8.7 For wet specimens, perform the test according &1. to immediately after removal of a test specimen from liquid (see ZA) and briefly placing it on blotting paper to remove excess water.
9 Calculation and expression of results
Maximum force is taken as the result of individual specimen, and round it to the nearest 0,1 N.
Calculate the arithmetic mean of the maximum force of the five specimens in both the machine and cross-machine directions respectively, round the arithmetic mean to the nearest 0,1 N, the results are expressed as the arithmetic means.
If required, calculate the coefficient of variation to the nearest, 0,1 %.
10 Test report
The test report shall include at least the following information:
a) a reference to this document, i.e. ISO 9073-4:202 1;
b) all details necessary for the identification of the material;
c) the arithmetic mean of the tests in both the machine direction and cross-machine direction. If five normal results for each direction cannot be obtained, state the maximum force for the individual test specimens only (see Clause 9)
d) the conditioning atmosphere used;
e) if required, the arithmetic mean of the wet state in both the machine direction and cross-machine direction. If live normal results for each direction cannot be obtained, state the maximum force for the individual test specimens only (see Clause 9)
f) if required, the coefficient of variation;
g) numberoftestspecimensand number of tests rejected and reasons for this;
h) any unusual features noted during the testing, or deviations from the standard procedure;
i) the date of test.BS EN ISO 9073-4 pdf free download.nonwovens

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