Five Methods for Material Judgment of Rubber Products
1 Medium Resistance Weight Increase Test
Sampling from the finished product, soaking in one or several selected media, weighing after a certain temperature and time, and deducing the type of material according to the change rate of weight and hardness.
For example, after soaking in 100 degree oil for 24 hours, the mass and hardness of NBR, fluorine gum, ECO and CR changed little, while the weight of NR, EPDM and SBR increased more than twice and the hardness changed greatly, and the volume expansion was obvious.
2 Hot Air Aging Test
Sample from the finished product and put it in the aging box for one day to observe the aging phenomenon. Graded aging can be gradually warmed up. For example, CR, NR, SBR will be brittle fracture, NBR EPDM and elasticity. Normal NBR will be brittle at 180 degrees, while HNBR will be brittle at 230 degrees, fluorine and silica gel still have good elasticity.
3 combustion method
Take a few samples and burn them in the air. Observation phenomenon.
Generally speaking, fluorine gum, CR, CSM are self-reliant from fire, even if the fire is ignited, it is much smaller than the general NR, EPDM. Of course, if you look carefully, the burning state, color and smell will also provide us with a lot of information. For example, NBR/pvc blend, when there is a fire source, splashes like water, extinguishes itself from the fire, smoke is strong and sour. It should be noted that sometimes flame retardants are added but halogen-free gums also extinguish themselves from fire, which needs to be further inferred by other means.
4. Measuring specific gravity
Electronic scales or analytical scales, accurate to 0.01 grams, plus a glass of water, a hair can be.
Generally speaking, the proportion of fluorine gum is the largest, more than 1.8, and CR ECO is obviously larger than 1.3. Consider these gums.
5 cryogenic method
Sample from the finished product and use dry ice and alcohol to create a suitable low temperature environment. Soak the sample in a low temperature environment for 2-5 minutes and feel soft and hard at the selected temperature. For example, at - 40 degrees, silica gel, which also has good heat and oil resistance, is soft compared with fluorine gel.