Three methods to test the goodness of rubber flexible joints
If you want to check the goodness of the rubber joint, there are three methods.
Low temperature method: take a small sample of rubber joint from the finished product and create a suitable low temperature environment with dry ice and alcohol. Soak the rubber joint sample in the low temperature environment for 2-5 minutes and feel the softness at the selected temperature. For example, if you compare silicone and fluorine rubber, which are also good at high temperature and oil resistance, with -40 degrees, silicone is softer.
Hot air aging test: take out the small sample of rubber joints from the finished product, put it in the aging box for a day, and observe the phenomenon of rubber joints after aging. The aging can be graded by gradually increasing the temperature. For example, under 150 degrees, CR, NR and SBR will be brittle and broken, but NBR EPDM is still elastic. Under 180 degrees, the ordinary NBR will be brittle and break; under 230 degrees, HNBR will be brittle and break, but fluorine rubber and silicone still have good elasticity.
Measure specific gravity: use electronic scale or analytical balance, accurate to 0.01g, plus a glass of water, a hair can be. Generally speaking, the specific gravity of fluorine rubber is larger, more than 1.8, CR ECO is also more than 1.3 specific gravity can be considered as these gums.
