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Rubber Quality Inspection
- Dec 29, 2018 -

There are strict quality requirements in rubber materials and products, such as tensile strength, modulus of elasticity, elongation, and aging resistance. Rubber products are used in high precision areas and these parameters are often demanding.


At the beginning of China's rubber development, the Rubber Products Committee was established, responsible for rubber research and development, academics, and quality supervision.


1. Resistance to medium weight gain experiment


The sample can be sampled from the finished product, immersed in one or several selected media, and weighed after a certain temperature time, and the type of the material is inferred according to the rate of change of the hardness change rate.


For example, immersing in 100 ° C oil for 24 hours, NBR, fluorine rubber, ECO, CR quality and hardness change rate is small, while NR, EPDM, SBR gain more than double the hardness and change greatly, volume expansion is obvious.


2. Hot air aging experiment


Sampling from the finished product, aging in an aging tank for one day, observing the phenomenon after aging. It can be graded and gradually warmed up. For example, CR, NR, SBR will be brittle at 150 °C, and NBR EPDM is also elastic. When it is raised to 180 °C, ordinary NBR will be brittle; at 230 °C, HNBR will also be brittle, and fluorine rubber and silica gel still have good elasticity.


3. Combustion method


Take a few samples and burn in the air. Observe the phenomenon.


In general, fluorine rubber, CR, CSM are at a loss from fire, even if the flame is burning, it is much smaller than the general NR and EPDM. Of course, if you look closely, the burning state, color, and smell will provide us with a lot of information. For example, NBR/PVC is glued together. When there is a fire source, there is a splash of fire. It seems to have water. It is self-extinguishing from the fire, and the smoke is rich and sour. It should be noted that sometimes the flame retardant but halogen-free glue will also be self-extinguishing from the fire, which is further inferred by other means.


4. Measuring specific gravity


Use an electronic scale or analytical balance, accurate to 0.01 grams, plus a glass of water, a hair can be.


In general, the specific gravity of fluorine rubber is 1.8 or more, and CR ECO is also more than 1.3.


5. Low temperature method


Sampling from the finished product, using dry ice and alcohol to create a suitable low temperature environment. The sample was soaked in a low temperature environment for 2-5 minutes and felt soft and hard at the selected temperature. For example, below 40 ° C, the same high temperature and oil resistance is very good contrast between silica gel and fluorine rubber, silica gel is relatively soft.