1、Medium resistant weight gain test
Samples can be taken from finished products, soaked in one or several selected media, weighed after a certain temperature and time, and the type of materials can be inferred according to the weight change rate and hardness change rate.
For example, after soaking in 100 degree engine oil for 24 hours, the quality and hardness change rate of NBR, fluororubber, ECO and CR are very small, while NR, EPDM and SBR have more than doubled in weight, changed greatly in hardness and expanded significantly in volume.
2、Hot air aging test
Take samples from the finished products and put them in the aging box for one day to observe the phenomenon after aging. Gradual aging can be used to gradually increase the temperature. For example, CR, NR and SBR will be brittle at 150 ° C, and NBR EPDM is still elastic. When the temperature rises to 180 °, ordinary NBR will be brittle; The HNBR will also be brittle at 230 degrees, and the fluorine glue and silica gel still have good elasticity.
3、Combustion method
Take a few samples and burn them in air. Observe the phenomenon.
Generally speaking, fluorine glue, CR and CSM are self extinguishing when they are out of fire. Even if the flame is ignited, it is much smaller than that of ordinary NR and EPDM. Of course, if carefully observed, the combustion state, color and smell will also provide us with a lot of information. For example, NBR/PVC adhesive blends, when there is an ignition source, the fire is splashing, as if there is water, self extinguishing from the fire, with thick smoke and sour taste. It should be noted that sometimes the glue added with flame retardant but without halogen will extinguish from the fire, which should be further inferred by other methods.
- 4 Specific gravity measurement
- Use an electronic scale or analytical balance, accurate to 0.01 g, plus a glass of water, a hair can be.
- Generally speaking, the proportion of fluorine glue is the largest, more than 1.8, and the proportion of CR ECO is more than 1.3. It can be considered that the proportion of these glue is obviously larger.
- 5 Low temperature method
- Take samples from the finished products and create a suitable low temperature environment with dry ice and alcohol. Soak the sample in a low temperature environment for 2-5 minutes, and feel the hardness at the selected temperature. For example, at – 40 ℃, silica gel is relatively soft compared with fluorine gel, which is also good at high temperature and oil resistance.