ISO 6133 Rubber and Plastics - Analysis of Multiple Peak Traces Obtained for Determination of Tear Strength and Adhesion Strength

The International Organization for Standardization (ISO) standard "ISO 6133 Rubber and plastics - Analysis of multiple peak traces obtained in the determination of tear strength and adhesion strength" describes five test methods used to calculate the tear strength and adhesion strength of vulcanized rubber or fabrics coated or bonded with rubber or plastics after testing. The results are calculated by determining the median and range of peak values ​​from a graphical plot of force versus time recorded during the test.

A trace for an adhesive strength test or a tear strength test may show several or many force peaks, depending on the material being investigated. The choice of calculation method depends on the number of peaks in the trace. The aim of this standard is to achieve greater uniformity in the evaluation and presentation of test results. However, these methods may only be applied when specified in another international standard. The requirements given in the relevant standard for apparatus, test piece preparation, conditioning, procedure and other similar details apply.

In certain cases, the given analysis methods may not be sufficient, for example for peak values ​​that show a trend over time. In cases where minimum force values ​​are of interest, the same calculation methods used for determining the range of peak values ​​can be used.

For the purposes of this standard, the following terms and definitions apply:

• A peak is the point at which the slope of the trace changes from positive to negative. For example, a peak occurs when the instantaneous maximum force occurs.
• The range expresses the difference between the largest and smallest observed values ​​of the observed force peaks.
• The full trace is a section of a graphical plot of force versus time between the time the first peak occurs and the time the test is terminated.

In carrying out tests, the median peak force and the range of peak force values ​​are generally determined from the peak force values ​​of the allowance for adhesion strength or tear strength by the appropriate method specified. A peak is considered valid only if the difference in force between the maximum and the following minimum is greater than 2 percent of the maximum force. In applying the methods described in this standard, the allowance being evaluated is assumed to be a time record of the force change during the test period. When analysing the allowance with a computer, the signal is filtered to prevent too many small peaks. This can be done by allowing the measured force to fall by a certain percentage and allowing a certain amount of time to elapse before a new peak is recorded. It may be necessary to adjust these factors when testing different materials to obtain approximately the same number of peaks as can be seen on a chart recorder.

The test methods were determined as follows:

• Method A: For traces with less than five peaks. The median, range, minimum and maximum of the force peak values ​​in the trace are determined. If there is only one force peak, its value is considered as the median.
• Method B: For traces with five to 20 peaks or where peak values ​​are calculated automatically. Only the peak values ​​of the central 80 percent of the full trace are considered and the median peak strength, range, minimum, and maximum of these values ​​are determined. Although it is possible to use this method for traces with more than 20 peaks, it is not recommended for manual calculations.
• Method C: For traces with more than 20 peaks that are clearly defined and easily measured and are not automatically calculated. A series of nine vertical lines are drawn starting from the exact centre of the trace and four more lines are drawn to the nearest 1 mm at equal distances of one tenth of the trace length on either side. Only the peak value located closest to each of the vertical lines is taken into account. The median peak strength and the range, minimum and maximum of these nine values ​​are determined.
• Method D: For wavy traces. When peaks are not clearly defined but form a wavy curve, only the arithmetic mean value is reported. This arithmetic mean value is reported as the midpoint between the maximum and minimum deviations of the trace, ignoring the initial rise at the beginning of the test.
• Method E: For traces that are too close to count. When peaks are not clearly defined but form a wavy curve, only the arithmetic mean value is reported. This arithmetic mean value is reported as the midpoint between the maximum and minimum deviations of the trace, ignoring the initial spike at the beginning of the test.

The trace analysis report should include the following information:

• Reference to this standard (ISO 6133)
• Reference to the test on which the calculation was made
• Calculation method used (A, B, C, D or E)
• Median peak force or average value for methods D and E
• Range of peak values
• Date of calculation

Our organization, which has been trying to support businesses from every sector with its testing, measurement, analysis and evaluation studies carried out in a wide range for years, has a strong staff that closely follows the developments in the world in the field of science and technology and constantly improves itself. In this context, testing services in accordance with the standard “ISO 6133 Rubber and plastics - Analysis of multiple peak traces obtained in the determination of tear strength and adhesion strength” are also provided to businesses.