Overview of rubber:
The rubber latex, rubber grass and other plant latexes are extracted and processed to produce materials with elasticity, insulation, impermeability to water and air. High elasticity polymer compound. Divided into two kinds of natural rubber and synthetic rubber. Natural rubber is made by extracting gum from rubber trees, rubber grass and other plants, and processed; synthetic rubber is obtained by polymerization of various monomers. Rubber products are widely used in various aspects of industry or life
Classification of rubber:
Rubber is divided into natural rubber and synthetic rubber according to raw materials. According to the shape, it can be divided into block raw rubber, latex, liquid rubber and powder rubber. Latex is a colloidal water dispersion of rubber; liquid rubber is an oligomer of rubber, which is generally a viscous liquid before being vulcanized; powdered rubber is processed into powder form by latex to facilitate ingredients and processing. The thermoplastic rubber developed in the 1960s did not require chemical vulcanization, but was formed using thermoplastic processing methods. Rubber is divided into general type and special type according to the use.
Rubber identification method:
1 Medium weight gain test
Samples can be taken from the finished product, soaked in the selected medium or several media, weighed after a certain temperature and time, and the type of material can be inferred according to the rate of change in weight and hardness.
For example, immersed in 100 degrees engine oil for 24 hours, NBR, fluorine rubber, ECO, CR quality and hardness change rate is very small, while NR, EPDM, SBR more than doubled the weight and hardness changes greatly, the volume expansion is obvious.
2 Hot air aging experiment
Take a sample from the finished product and put it in an aging box for one day to observe the phenomenon after aging. Can be graded aging and gradually heated up. For example, CR, NR, SBR will be brittle at 150 degrees, and NBR EPDM is still elastic. Normal NBR will break brittlely when it rises to 180 degrees; while HNBR will brittlely break when it is 230 degrees, fluorine rubber and silicone still have good elasticity.
3 Combustion method
Take a little sample and burn it in the air. Observe the phenomenon.
Generally speaking, fluoroelastomer, CR, CSM are self-sustaining from fire, even if burning flames, it is much smaller than that of NR and EPDM. Of course, if you look closely, the burning status, color, and smell will also provide us with a lot of information. For example, when NBR / PVC is used in combination with glue, when there is a fire source, the fire splashes and spatters. It seems to be water-like. It extinguishes from the fire, and the smoke is thick and sour. It should be noted that sometimes the flame retardant but halogen-free glue will also extinguish itself from the fire, which must be further inferred by other methods.
4 Test specific gravity
Use an electronic scale or analytical balance, accurate to 0.01 grams, plus a glass of water, a hair strand.
Generally speaking, fluorine rubber has the largest specific gravity, above 1.8, and CR ECO is more than 1.3, and the specific gravity is obviously larger. These adhesives can be considered.
5 Cryogenic method
Take samples from the finished product 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 degrees Celsius, silica gel and fluorine rubber, which are also resistant to high temperature and oil, are softer.
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