How do you measure tearing strength of paper?

 

1. Sample Preparation: A few representative samples are cut from the paper to be tested. The samples should be rectangular in shape and sized according to the applicable standards (e.g. ASTM D689, ISO 1974). The samples should be free of any visible defects or damage.

 

2. Testing Instrument: The Elmendorf Tear Strength Tester is commonly used to measure the tear strength of paper. The tester consists of a device with a swinging arm and swinging arm fixture, a sample fixture, and a cutting knife.

 

3. Test Procedure:

   a. Set up the Elmendorf Tear Tester according to the manufacturer's instructions, making sure that the test instrument has been properly calibrated.

   b. Place a sheet of sample to be tested securely in the sample fixture, ensuring that the tear path is aligned with the pendulum fixture.

   c. Swing the pendulum arm to its initial position and release it, allowing it to swing down and tear the sample.

   d. The arm stops swinging after tearing the sample. The angle at which the arm swings from the initial position indicates the tear strength of the paper.

   e. Repeat the test with multiple samples to ensure accuracy and reliability.

 

4. Calculation: The tear strength of paper is expressed as Elmendorf Tear Resistance and is usually reported in units such as mN (milli-Newton) or gf (gram-force). The exact calculation depends on the specifications of the tear test method used.

 

5. Reporting of results: The tear strength results are reported, including the average tear resistance value and any other relevant information, such as test conditions and standards followed.

 

It is important to note that different standards may have slight differences in test set-up and calculation methods. It is therefore important to refer to the specific standard (e.g. ISO, ASTM) for a detailed description of the methodology and reporting requirements, depending on the paper material being tested.