1. Resistance to weight gain experiment

Samples can be taken from the finished product, soaked in one or more selected media, weighed after a certain temperature time, and the type of material can be inferred based on the rate of change in weight and hardness. For example, when immersed in 100 ° C engine oil for 24 hours, the change rate of NBR, fluorine rubber, ECO, CR quality and hardness is very small, while NR, EPDM, SBR have more than doubled the weight and the hardness changes greatly, and the volume expansion is obvious.

2. Hot air aging experiment

Take a sample from the finished product and place it in an aging box for one day to observe the phenomenon after aging. Can be graded and gradually heated. For example, CR, NR, and SBR are all brittle at 150 ° C, and NBR EPDM is also flexible. Normal NBR will be brittle when it rises to 180 ℃; HNBR will also be brittle when it is 230 ℃. The fluorine rubber and silica gel still have good elasticity.

3. Combustion method

Take a small sample and burn it in the air. Observe the phenomenon. Generally, fluorine rubber, CR, and CSM self-retain from fire. Even if the flame is burned, it is much smaller than ordinary NR and EPDM. Of course, if you look closely, the burning state, color, and smell will also provide us with a lot of information. For example, NBR / PVC is used in combination with glue. When there is a fire source, the fire splashes and splatters. It seems to be water-like. It extinguishes itself from the fire, and the smoke is thick and sour. It should be noted that sometimes flame retardants but halogen-free glues will self-extinguish from the fire, which must be further inferred by other methods.

4. Specific gravity

Use an electronic scale or analytical balance, accurate to 0.01 grams, plus a glass of water, and a hair strand. Generally speaking, the fluorine rubber has the largest specific gravity, more than 1.8, and CR ECO is more than 1.3, and the specific gravity is obviously larger. These rubbers can be considered.

5. Low temperature method

Take a sample from the finished product and make a suitable low temperature environment with dry ice and alcohol. Soak the sample in a low-temperature environment for 2-5 minutes and feel soft and hard at the selected temperature. For example, when the temperature is lower than minus 40 ° C, the same high temperature and oil resistant silica gel and fluorine rubber are compared.