Several common rubber identification methods

2022/07/15 09:12

1. Resistance to medium weight gain test

The finished product can be sampled, soaked in one or several selected media, weighed after a certain temperature and time, and the type of material can be inferred according to the weight change rate and the hardness change rate.

For example, immersed in 100 degree oil for 24 hours, NBR, fluorine rubber, ECO, CR has a small change in quality and hardness, while NR, EPDM, SBR more than doubles in weight and changes in hardness greatly, and the volume expansion is obvious.

2. Hot air aging test

Take samples from the finished products, put them in the aging box for one day, and observe the phenomenon after aging. Gradual aging can be gradually increased. For example, CR, NR, and SBR will be brittle at 150 degrees, while NBR EPDM is still elastic. When the temperature rises to 180 degrees, the ordinary NBR will be brittle; and the HNBR will also be brittle at 230 degrees, and the fluorine rubber and silicone still have good elasticity.

3. Combustion method

Take a small sample and burn it in the air. observe the phenomenon.

Generally speaking, fluorine rubber, CR, CSM are free from fire, and even if the flame is burning, it is much smaller than the general NR and EPDM. Of course, if we look closely, the state of combustion, color, and smell also provide us with a lot of information. For example, when NBR/PVC is combined with glue, when there is a fire source, the fire splashes and seems to be like water. It should be noted that sometimes the flame retardant but halogen-free glue will also self-extinguish from the fire, which should be further inferred by other means.

 4. Measuring specific gravity

Use an electronic scale or analytical balance, accurate to 0.01 gram, plus a glass of water and a hair.

Generally speaking, fluorine rubber has the largest specific gravity, above 1.8, and most of CR ECO products have a large proportion above 1.3. These glues can be considered.

5. Low temperature method

Take a sample from the finished product and use dry ice and alcohol to create a suitable cryogenic environment. Soak the sample in a low temperature environment for 2-5 minutes, feel the softness and hardness at the selected temperature. For example, at -40 degrees, the same high temperature and oil resistance silica gel and fluorine rubber are compared, and the silica gel is softer.