EPDM reclaimed rubber retains the excellent high and low temperature resistance and anti-aging properties of EPDM rubber. The ordinary molded products produced are low in cost and stable in performance, and are widely used in automobiles, industrial manufacturing and other fields. When using EPDM reclaimed rubber to produce ordinary EPDM molded products, the design of the vulcanization system directly affects the quality and vulcanization efficiency of the vulcanized rubber. Rubber product manufacturers need to consider the performance requirements, production efficiency, cost and other aspects to choose a suitable vulcanization system.
1. Recommended curing system
(1) Sulfur vulcanization system
When using sulfur-accelerator for vulcanization of EPDM reclaimed rubber molded products, vulcanization systems with different sulfur content are generally selected according to the processing method and performance requirements of the molded products. When the common vulcanization system with high sulfur content (1.5-2.5 parts) is used for vulcanization, the vulcanized rubber is mainly composed of polysulfide cross-linked bonds. Before aging, the rubber has good physical and mechanical properties but poor heat resistance and poor high-temperature permanent deformation. When low-sulfur compounding (sulfur content is less than 1 part) or sulfur donor and other effective vulcanization systems are used, the vulcanized rubber will only form a single-sulfur cross-linked network, which has good heat resistance and high temperature permanent deformation performance but low mechanical strength.
The vulcanized EPDM reclaimed rubber vulcanized with a semi-effective vulcanization system has the middle sulfur content and vulcanized rubber performance. The vulcanized rubber has higher mechanical strength, better heat resistance and high temperature permanent deformation, which can meet the needs of more rubber 2YLYY323 products. It should be noted that when selecting an effective vulcanization system for EPDM reclaimed rubber, the solubility limit of the accelerator in the EPDM reclaimed rubber must be considered, especially when it is used with EPDM raw rubber.
(2) Peroxide curing system
The peroxide-vulcanized EPDM reclaimed rubber vulcanizate generates carbon-carbon cross-linked bonds, with high bond energy, good heat aging resistance, compression set, and relatively low physical and mechanical properties. In actual production, many manufacturers who use EPDM reclaimed rubber to produce ordinary molded products choose to use sulfur and peroxide together to prepare products with better comprehensive performance.
2. Vulcanization system not recommended
When vulcanizing EPDM raw rubber, quinone oxime vulcanizing agent and metal oxide activator system are also used. The vulcanized rubber has good aging resistance but poor mechanical strength, high hardness, and high cost. EPDM reclaimed rubber is not recommended to produce ordinary molded products. use. When choosing a reactive resin vulcanization system such as phenolic resin, the carbon-carbon cross-linked network formed by EPDM vulcanizate can give the rubber good heat resistance and compression set resistance, but the vulcanization speed is slow during vulcanization and the hardness of the vulcanizate is low , The elongation at break is too low, so it is not recommended.
In actual production, sulfur curing system and peroxide curing system are commonly used curing systems for EPDM reclaimed rubber products. Different vulcanization systems have different vulcanization characteristics. When using EPDM reclaimed rubber to produce cost-effective ordinary molded products, the rubber product manufacturer must choose a suitable vulcanization system according to actual needs, and appropriately adjust the variety and dosage of the reinforcing system, softening system, and anti-aging system in the formula. Optimize the quality of finished products and reduce more raw material costs.
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