EPDM recycled rubber has excellent high temperature resistance, ozone resistance, weather resistance, can be used alone or in combination with EPDM rubber to produce automotive seals, industrial hoses, building seals, waterproof materials, wires and cables and other fields, some products require good high-temperature compression set performance of rubber materials, rubber product manufacturers can improve the high-temperature compression set performance of rubber materials by reasonably designing EPDM recycled rubber formulas.
1. Selection skills of EPDM recycled rubber and EPDM rubber
When using EPDM recycled rubber to produce rubber products with strict requirements for high-temperature compression set performance, it is recommended to choose EPDM recycled rubber with high EPDM content, and if necessary, use it with EPDM rubber with low ethylene content E5LYY1027 and high Mooney viscosity. In actual production, EPDM compounds with low ethylene content can give rubber products better heat resistance and aging resistance, while high Mooney viscosity helps to improve the entanglement of rubber molecular chains and form a more stable cross-linking network.
2. How to design a vulcanization system to improve the high-temperature compression set performance of EPDM recycled adhesives
It is recommended to choose a peroxide vulcanization system, such as DCP+TAIC(HVA2)+TMPMA (trihydroxymethylpropane triacrylate), which can form heat-resistant cross-linked bonds dominated by C-C bonds, with higher bond energy and stronger thermal stability, which can effectively avoid the fracture and recombination of cross-linked bonds at high temperatures, and significantly reduce the permanent deformation of rubber after compression. TAIC and TMPMA as co-crosslinking agents can promote the crosslinking efficiency during peroxide vulcanization, and improve the crosslinking density and network uniformity.
3. How to design a reinforcement filling system to improve the high-temperature compression set performance of EPDM recycled adhesive
To improve the high-temperature compression set performance of EPDM recycled rubber, it is recommended to choose N330, N550, N990 and other varieties of carbon black reinforcement, which can be evenly dispersed in the recycled rubber and form a tight physical bond of rubber molecular chains.
N330 can significantly improve the tensile strength, tear resistance, wear resistance and elasticity of the compound; N550 is easy to disperse, which can give the rubber high stiffness, and the high temperature resistance and thermal conductivity of vulcanized rubber are good. N990 has weak reinforcement but has little effect on compression set. Reasonably control the amount of carbon black, appropriately increase the glue content, increase the proportion of rubber molecular chains, reduce the obstruction of fillers to the movement of molecular chains, and further improve the elastic recovery ability of EPDM recycled rubber vulcanized rubber at high temperatures.
4. How to design an anti-aging system to improve the high-temperature compression set performance of EPDM recycled glue
In the high-temperature environment, rubber is prone to molecular chain degradation due to oxidation, which in turn intensifies the compression set and improves the high-temperature compression set performance of EPDM recycled rubber.
The reactive anti-aging agent MC can chemically bond with the rubber molecular chain, is not easy to precipitate at high temperature, and maintains the antioxidant effect for a long time. The heat-resistant anti-aging agent 445 and RD+MB composite system have excellent thermal and oxygen stability properties, which can effectively inhibit the free radical chain degradation reaction at high temperature and maintain the integrity of the cross-linked structure.
5. How to design a softening system to improve the high-temperature compression set performance of EPDM recycled adhesive
Excessive softener dosage will lead to the migration or volatilization of softener at high temperature, destroy the cross-linked network structure, and increase compression set set. To improve the high-temperature compression set performance of EPDM recycled adhesive, it is necessary to minimize the amount of softener. When softeners must be used, give priority to softeners with good compatibility and heat resistance, such as liquid EPDM or paraffin oil, and the dosage is strictly controlled at about 5 parts.
Rationally designing the formula of recycled rubber products and improving the high-temperature compression set performance of EPDM recycled rubber can further expand the application scope of recycled rubber and reduce more costs under the premise of ensuring the performance of rubber products.
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