What are the causes of aging of rubber joints and what are the reasons for preventing aging?
What are the causes of aging of rubber joints and what are the reasons for preventing aging?
As rubber joints are subject to pressure and air oxidation during use, it is an important reason that affects the flexibility of rubber joints. In the process of processing, storage and use of rubber and its products, the physical and chemical properties and mechanical properties of rubber gradually deteriorate and lose their use value due to the joint action of internal and external factors. This change is called rubber aging. Everything is its service life and service life, and so is the rubber joint. Then what are the reasons for aging of rubber joints and the ways to prevent aging?
1. One of the key causes that jeopardize the application of rubber joints is the working pressure and oxidation during the whole process of application. In the production and processing, storage and use of plastic and the whole process, because of the overall effectiveness of the internal and external elements, the physical and chemical properties of plastic and physical properties slowly decline and become more and more useless. This type of transformation is called plastic aging. The surface layer is cracked, sticky, hardened, softened, delaminated, discolored, moldy and other conditions, so it can be bent. Rubber joints should be maintained regularly during the application process. For some that have been used for a period of time, aging is more serious. It must be regularly checked and disassembled and replaced
2. Pay attention to the way when assembling to increase the service life of rubber joints. When assembling rubber joints, they should be in a certain situation, and the assembly should not be deformed by human factors. This will lead to too early destruction and weaken the actual effect of application. If assembled around the entrance and exit of the pump or at the corner of the pipeline threaded joints, and in the air application of high voltage and multi-layer building, the pipeline must have a support frame or fixed bracket, and the bearing force support frame and fixed bracket must exceed the shaft.
3. When assembling the rubber joint with groove, all the strengthening rings on both sides of the ball are stuck into the flange groove body to avoid pulling off the ball and flange when the pipeline is under pressure. When assembling the foot bolts, twist the symmetrical foot bolts at once to ensure that all the balls and flanges are assembled in time. When the rubber joint is connected to the flanged pipe, the unnecessary nut should be widened to one end of the pipe flange to avoid squeezing or puncturing the arc part of the joint when the external thread narrows and expands. Twist the ground bolts symmetrically so that all the ground bolts are tightened. In areas where the actual operating standards are severe, in addition to adding flat washers, self-locking nuts should be installed to avoid loosening of the nuts
4. Oxygen will react with the rubber molecules in the free radical chain in the rubber, resulting in molecular chain breakage or excessive cross-linking, thus causing changes in rubber properties. Therefore, oxidation is one of the important causes of rubber aging.
5. Ozone aging of rubber joints is a surface reaction, and the reaction attempt of unstressed rubber surface is 10-40 molecules thick, or (10-6)^2mm thick. The chemical activity of ozone is much higher +than oxygen and much more destructive. It also acts by breaking molecular chains, but the effect of ozone on rubber varies depending on whether the rubber is deformed or not. When applied to non-deformed rubber (mainly unsaturated rubber), cracks and "ozone cracks" appear perpendicular to the direction of stress. When applied to deformed rubber, only ozone film is formed on the surface without cracking.
6. The role of moisture can be divided into two aspects: when the rubber is damp in humid air or immersed in water, it is easy to destroy, which is due to the water-soluble substances and hydrophilic groups in the rubber by water extraction, dissolution, hydrolysis or absorption. In particular, the alternating effects of water immersion and atmospheric exposure accelerate the damage of rubber. However, in some cases, moisture does not damage the rubber and can even delay aging.
7. If the rubber is in contact with oil medium for a long time during use, the oil will penetrate into the rubber and make it swell, thus reducing the strength and other mechanical properties of the rubber. Oil can make the rubber swell dissolve, which is because after oil penetrates into the rubber, the molecules diffuse each other, thus changing the network structure of vulcanized rubber.
