Every year, China produces a large number of used tires, of which a part of the waste tires are processed in fine powder tires for various uses. The use of EPDM rubber/reclaimed rubber to produce rubber products can also add appropriate amount of tire rubber powder, which can reduce the raw material cost of rubber products and improve the process performance of EPDM rubber products.
1. Why do some people think that EPDM cannot be added with rubber powder
The saturation of waste tire rubber powder and EPDM rubber is very different. The solubility of vulcanizing agent in tire rubber powder with low saturation is high and the cross-linking speed is high. Therefore, the vulcanizing agent of EPDM rubber products will be from three yuan. Ethylene-propylene rubber migrates in the tire rubber powder, resulting in over-curing of sulfur in the tire rubber powder. The sulfur curing agent in the EPDM rubber material reduces the occurrence of sulfur deficiency. The two co-vulcanization properties are poor, resulting in the vulcanizing agent performance. As the amount of tire rubber powder increases, it decreases.
2. The performance of EPDM rubber products changes with the increase of waste tire rubber powder
When EPDM rubber/reclaimed rubber is used in the production of rubber products, the tensile strength and the settling stress of the rubber compound will decrease with the increase of the amount of waste tire rubber powder; the elongation at break, the tear strength and Compression set will change with the increase of the amount of tire rubber powder, and then increase first and then decrease. Generally, the peak value of rubber powder is about 10 parts. The peak value of the elongation at break and the tear strength of the EPDM rubber material is the result of the impediment effect of the scrap tire rubber powder on the crack and the energy dissipation effect of the interface. Reasonably design the EPDM rubber/recycled rubber product formula with tire rubber powder and adjust the tire rubber powder dosage to find a balance between the performance and cost of EPDM rubber products.
3. Formulation skills for EPDM rubber products with tire rubber powder
When adding tire rubber powder to the EPDM/recycled rubber product formulation, the EPDM rubber/recycled rubber product vulcanization system design, rubber powder modifier selection, tire rubber powder fineness will affect the EPDM rubber products. performance.
(1) Because the co-vulcanization properties of waste tire rubber powder and EPDM rubber products are poor, the design of the vulcanization system is particularly important. Generally, the sulphur and peroxide compounding vulcanization system is generally used in the EPDM rubber compound. The high solubility reduces the difference in the vulcanization reaction speed between EPDM rubber and waste tire rubber powder. The vulcanization rate in the peroxide/sulfur shared vulcanization system is not completely dependent on the EPDM rubber saturation as in the sulfur vulcanization system, and the EPDM phase and the tire rubber powder phase have relatively better co-crosslinking properties. The tensile strength, elongation at break, tensile stress and tear strength of EPDM rubber products vulcanized with a sulphur/peroxide vulcanization system do not change much with the increase in the amount of tire rubber powder. The ethylene propylene diene rubber product obtained when the amount of powder is 30 parts has better performance.
(2) Select thermosetting phenolic resin as tire rubber modifier. Thermosetting phenolic resin is a kind of resin with good stability, heat resistance, flame retardancy and electrical insulation. It can be used as tire rubber powder surface modifier and co-crosslinking agent with ethylene propylene diene rubber. The ethylene-propylene rubber and tire rubber co-vulcanizability.
(3) In practical production, the smaller the particle size of the tire rubber powder, the greater the contact area with the EPDM rubber and various compounding agents, the smaller the local stress, the greater the interface force, and the EPDM adhesive. The greater the tensile strength and the settling stress of the material, the better the physical and mechanical properties of the EPDM rubber products; but the excessively large fineness of the rubber powder will also affect the tear strength of the EPDM rubber compound. Adding tire rubber powder to EPDM rubber/recycled rubber products, the fineness of tire rubber powder is controlled to be about 60 mesh.
With the continuous development of tire rubber powder production technology and continuous updating of equipment, tire rubber powder performance is getting better and better. In rubber products, it can not only be used as a filler material, but also can have more range of use. Extending the application fields of tire rubber powder is of great significance for solving the environmental pollution of waste tires and alleviating the shortage of rubber resources.
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