Water Absorption Testing of Plastic Materials - A Guide

 

1. Sample Preparation: Cut and prepare a good specimen from the material to be tested, making sure that the size of the specimen meets the requirements of the test. The size and shape of the specimen may vary depending on the type of material and intended application.

 

2. Conditioning: The specimen is placed in a controlled environment and dried or wetted appropriately to bring the specimen to a moist equilibrium state. This step is to ensure a consistent starting point for testing.

 

3. Initial Weighing: The conditioned specimen is weighed using a precision balance to determine the initial weight.

 

4. Immersion: The specimen is placed in a water medium at a specified temperature, either fully immersed or in surface contact only, depending on the needs of the test and the properties of the material.

 

5. water loading: the specimen is immersed in an aqueous medium for a specified period of time. The normal test time is 24 hours, but this can vary depending on the material and the purpose of the test.

 

6. Drying: At the end of the immersion time, the specimen is removed from the aqueous medium and the surface of the specimen is gently wiped with an absorbent material, avoiding excessive squeezing or wiping to prevent the removal of inhaled water.

 

7. Final weighing: The specimen is quickly removed from the water and weighed immediately before significant evaporation occurs to accurately determine the final weight.

 

8. Calculation: A ratio is obtained by subtracting the initial weight from the final weight and dividing the result by the initial weight. This ratio is then multiplied by 100 to express water absorption as a percentage.

 

When performing a water absorption test, be sure to refer to the specific ASTM standard or method associated with the material being tested to ensure an accurate and precise testing procedure. In addition, there may be other available test methods depending on the type of material being tested and industry requirements.