ISO 1924-3 Paper and Board - Determination of Tensile Properties - Part 3: Constant Elongation Rate Method (100 mm/min)

Developed by the International Organization for Standardization (ISO), this part of the ISO 1924 standard specifies a method for measuring tensile strength, strain at break, tensile energy absorption, and tensile hardness using a testing machine operating at a constant rate of elongation (100 mm/min). ISO 1924-3 also specifies equations for calculating the tensile index, tensile energy absorption index, tensile stiffness index, and modulus of elasticity.

When determining tensile hardness, greater accuracy is required in the elongation measurement than when determining other tensile properties. If the elongation is determined with less accuracy, the resulting tensile hardness value is not in accordance with this part of ISO 1924.

This part of ISO 1924 applies to all paper and paperboard, including high-extensibility papers such as crepe papers and expandable burlap, but excludes low-density papers such as tissue papers and tissue products to which ISO 12625-4 conforms.

This part of ISO 1924 was developed to specify conditions for determining the tensile properties of paper, including the tensile hardness and tensile hardness index, using a higher elongation rate than that specified in the most widely used ISO 1924-2. tensile strength, tensile strength at break, tensile energy absorption and modulus of elasticity are measured.

In ISO 1924-2, tensile properties are measured at a constant elongation rate of 180 mm/min at a test interval of 20 mm. For the measurement of tensile hardness in this part of ISO 1924, a higher accuracy in the elongation registration is also required compared to ISO 1924-2.

This part of ISO 1924 specifies the fastest of the two methods. In addition to the properties measured in ISO 1924-2, tensile hardness is also measured. The tensile properties are measured at a constant elongation rate of 100 mm/min over a 100 mm test interval, and the elongation is recorded with greater accuracy than the accuracy in ISO 1924-2.

This part of ISO 1924 differs from existing standards for testing tensile properties in that the test gap, ie the distance between the clamping lines, is 100 mm, regardless of the type of sample to be tested. The elongation rate was increased to 100 mm/min to reduce the testing time, so it was possible to test a larger number of samples in a given time.

The results of the tensile tests depend on the elongation rate applied and the test interval. The effect of velocity dependence and test interval may vary with paper quality and differ for tensile strength, strain at break, tensile energy absorption, and tensile stiffness. In a study within the SCAN test, when comparing results using ISO 1924-2 and this part, the elongation rate ranged from 20 mm/min (180 mm at test span length) to 100 mm/min (at a test span length of 100 mm).

It is not possible to predict the exact relationship between the results and this part of ISO 1924 for any paper whose tensile properties are determined using ISO 2-1924. This relationship can only be determined by laboratory experiments.

This part of ISO 1924 uses the same terminology and symbols as in the general literature on materials physics and mechanics.

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