Testing method for tear strength of rubber products

The test for rubber tear strength is determined through a tear test, with specimens in the shape of pants, Delft, crescent, and right angle. The preparation of specimens is similar to that of tensile specimens, with the following main points to be noted:

(1) When cutting the sample, the direction of the tear angle bisector of the cutting blade (tear direction) should be consistent with the rolling direction.

(2) The number of samples shall not be less than 5.

(3) Measure the thickness of at least 3 points in the test area of the sample using a thickness gauge with an accuracy of 0.01mm, and take the median as the sample thickness. The thickness value shall not deviate by 2% from the selected value. When comparing multiple groups of samples, the average thickness of each group of samples shall be within 7.5% of the average thickness of each group of samples.

The steps for testing tear strength are as follows:

(1) Check equipment and instruments, prepare equipment and instruments, related tools, and clean the environment;

(2) Power on and set relevant parameters (such as speed, mode, etc.);

(3) Clamp the sample in the upper and lower clamps to determine the scale and evenly clamp it in parallel positions. When conducting tests on right angle or crescent shaped specimens, align the axial direction of the specimen with the tensile direction and clamp it into upper and lower clamps to determine the scale, in order to ensure sufficient and uniform clamping in parallel positions;

(4) After placing the sample on the clamp of the tensile testing machine, adjust the tensile machine (such as using a computer tensile machine, starting the software to select the test method, setting the parameter input size, etc.), start the testing machine, stretch the sample at the specified speed until the sample tears, and record the larger value.

Tear strength calculation: T (SZ)=F/d; In the formula, "F" represents the force acting on the sample during tearing (calculated according to the provisions of GB/T12833, taking the median, unit: N), "d" represents the thickness of the sample (mm or cm), and T represents the tear strength (N/MM or N/cm).

At least 5 samples are required for each test sample, and the test results are represented by the median and larger/smaller values of the samples in each direction, with data accurate to whole digits. The individual value and average value of each sample shall not exceed 15%, and the number of samples after selection shall not be less than 3.