” >Characteristics of acrylic rubber The saturation of the acrylic rubber structure and the polar ester side chain determine its main application properties , that is, it has excellent thermal oxygen aging resistance and oil resistance, but poor cold resistance, water resistance, and solvent resistance.
” >1. Resistance to heat, oxygen aging and oil resistanceAcrylic rubberThe main chain is composed of saturated hydrocarbons and has carboxyl groups, which are larger than those on the main chain. Diolefin rubber with double bonds is stable, especially resistant to heat and oxygen aging. Its service temperature can be 30~60℃ higher than that of nitrile rubber. The maximum service temperature is 180℃. It can be used intermittently or for a short period of time. Reaching about 200℃, there is no obvious change after aging in hot air at 150℃ for several years.
” >
” >Several kinds of rubber 8 hours Aging, the temperature at which the tensile strength decreases by 25% (with carbon black) is compared as follows: Silicone rubber 279℃ Styrene-butadiene rubber 134℃Acrylate rubber 218℃ Natural rubber 102℃ Neoprene rubber 155℃ Acrylate The thermal aging behavior of rubber is different from both the thermal degradation type and the thermal hardening type, but is somewhere in between, that is, when aging in hot air, the tensile strength and elongation at break of the rubber first decrease, and then the The tensile strength increases, gradually becomes hard and brittle and ages.
” >Because the main chain of the macromolecule is stable, the thermal stability of the side chain is poor in comparison, resulting in stress relaxation and deformation when the rubber is subjected to elongation or compression deformation at high temperatures. The deformation phenomenon is significant. Although some new acrylic rubbers have greatly improved this performance, acrylic rubber is not very suitable for products that are required to withstand large tension at high temperatures or be used in a compressed state.
” >The thermal and oxygen aging resistance of different varieties of acrylic rubber varies depending on the activity of the cross-linking monomers contained and the types of cross-linking agents used. The difference is that the chlorine-containing polyamine cross-linked type is the best and the soap cross-linked type is the worst.
” >But these differences do not make them more heat-resistant Level up. The polar ester side chain of Acrylic rubber makes its solubility parameters consistent with a variety of oils. In particular, mineral oils are far apart and therefore exhibit good oil resistance, which is an important characteristic of acrylic rubber. Its oil resistance at room temperature is generally similar to that of nitrile rubber with medium and high acrylonitrile content, and is better than chloroprene rubber, chlorosulfonated polyethylene, and silicone rubber. But in hot oil, its performance is far superiorFor nitrile rubber, see Table 15-3.
” >Acrylic rubber has been immersed in hot oil for a long time. Ozone and oxygen are blocked, so its performance is more stable than in hot air. It can be established that in oils with temperatures below 150°C, acrylic rubber has oil resistance similar to that of fluororubber; in oils with higher temperatures, it is second only to fluororubber. In addition, it is resistant to animal and vegetable oils. , synthetic lubricants, and silicate hydraulic oils have good performance.
微信扫一扫打赏
Chinese