How to improve the temperature resistance of rubber?
Resistance to hot air aging or heat aging is becoming increasingly important, especially in automotive applications where rubber parts are mostly used in covered spaces with high ambient temperatures. Automotive manufacturers have felt increasing pressure to commit to longer service lives for their rubber parts. Anaerobic heat aging properties and heat and air aging properties are different. The rubber has better heat resistance, but may still not withstand oxygen attack.
Note: These general test protocols may not be applicable to each specific case. Any one of the variables that can improve air-aging resistance or heat-aging resistance will definitely affect other properties, either for better or worse.
1. Perfluoroelastomer
If the rubber material is required to have excellent heat resistance, you should choose perfluorinated rubber. It is reported that the use temperature of perfluoroelastomer is up to 316℃.
2、 Fluorine rubber
Fluorine rubber FKM has excellent heat resistance, and it can be used at temperatures up to 260℃. In order to further strengthen the high temperature resistance of fluorine rubber, you need to choose the right acid acceptor (acid absorbent), such as low activity magnesium oxide, high activity magnesium oxide, calcium oxide, calcium hydroxide, zinc oxide, etc. Fluoroelastomer's heat resistant air aging performance is also very good, and the use temperature can be as high as 200℃. By choosing bisphenol AF as the vulcanization system, the heat aging resistance of the rubber will be better. Used in harsh engine oil environment, the heat aging resistance of ternary fluoroelastomer made from vinylidene fluoride, tetrafluoroethylene and propylene is better than the general fluoroelastomer. This is due to the replacement of hexafluoropropylene by propylene in the polymerization process.
3、 HNBR
The higher the degree of hydrogenation, the better the heat resistance of HNBR, because there is almost no unsaturated double bond on the main chain that is unstable. Some HNBRs can still be vulcanized with sulfur because they still have some unsaturated double bonds. However, if vulcanized with peroxide, the heat resistance of the compound will be improved. For HNBR rubber, TOTM can give better heat resistance than DOP because of the low volatility and high molecular weight of these trioctyl plasticizers.
4. Neoprene
W-type neoprene has better heat aging resistance than G-type neoprene. Diphenylamine octanoate is a better antioxidant for neoprene, which can effectively improve the heat resistance.
5、 EPDM
EPDM will still have good heat resistance at 125℃ after suitable fit. The use of peroxide vulcanized EPDM, can make the rubber has better heat resistance.
6、 Low viscosity vapor phase method EPDM
High ethylene content and ultra-low viscosity vapor phase EPDM, can be filled with a large number of fillers, because of the high ethylene content, processing does not need to join the processing of heat-resistant air aging unfavorable and resin, still can make the rubber with good processing properties, so the actual heat resistance of the rubber is improved.
7、 Avoid using high styrene resin
Avoid adding high styrene resin to the rubber used in high temperature.
8、 Talcum powder
In EPDM hose rubber, replace 40% of carbon black with talcum powder, which can improve the heat aging resistance of the rubber. Some grades of talcum powder have more outstanding advantages than treated or untreated clay in this regard.
9、 High viscosity plasticizer
Among plasticizers, high viscosity plasticizers can give better heat aging resistance than low viscosity plasticizers. Because the high viscosity plasticizer usually has high molecular weight, not easy to volatilize, thus good stability and good heat resistance.
10、Rape seed oil for neoprene
In order to make neoprene have better resilience, canola oil is needed because it has low viscosity, which makes the rubber have low hysteresis and low volatility, which can make the rubber have good aging resistance.
11、Effective EV/semi-effective SEV vulcanization system
In the effective or semi-effective vulcanization system, the ratio of accelerator and sulfur is high, that is, "high promotion and low sulfur" system, with "sulfur to the body" instead of single sulfur, in this vulcanization system, the proportion of single sulfur bond and double sulfur bond in the vulcanized rubber is higher, because of its stability In this vulcanization system, the ratio of single sulfur bond and double sulfur bond is higher than that of multi-sulfur bond, therefore, the heat resistance stability of the rubber is improved and the heat aging resistance is improved.
12、Zinc oxide
Vulcanization / sub-sulfuramide vulcanization system of the rubber, filled with more zinc oxide, can give the rubber better heat aging properties and better resistance to post-sulfur.
13、Peroxide vulcanized EPDM rubber
In the peroxide vulcanized EPDM compound, ZMTI is chosen as the antioxidant, which can give the compound higher modulus and heat aging resistance.
