Unvulcanized EPDM rubber on the market, waste EPDM rubber products, such as washing machine seals, processed EPDM reclaimed rubber has the characteristics of high and low temperature resistance, ozone resistance, weather resistance, high insulation, etc., can be used separately Or it can be used with EPDM virgin rubber to produce EPDM rubber products, effectively reducing the cost of raw materials. In actual production, peroxide curing system and sulfur curing system are two commonly used curing systems for EPDM reclaimed rubber. What is the difference among the two, can they be used together, and how to choose?
1. Vulcanization characteristics
Peroxide vulcanization produces CC cross-linked bonds. The initial decomposition temperature is high, and a higher vulcanization temperature must be used; but at the vulcanization temperature, the scorch time of peroxide is very short, the vulcanization rate is low, and the vulcanization time is long. The oxide system is a typical "fast start, slow speed" vulcanization system, which is not conducive to improving the production efficiency of vulcanization of EPDM reclaimed rubber. In actual production, peroxide-vulcanized EPDM reclaimed rubber has a small vulcanization reaction and does not produce nitrosamines, but the adjustment of vulcanization parameters is poor.
When the EPDM reclaimed rubber is vulcanized with sulfur, a varying number of sulfur bonds will be generated. During the vulcanization process, the vulcanization parameters can be adjusted well, the scorch safety is high, the vulcanization speed is faster, the vulcanization curve is flat, and the heat Air continuous vulcanization 2YLYY1118 has good adaptability, but vulcanization reaction may occur during the vulcanization process, and the co-vulcanization among rubbers of different polarities is poor, and nitrosamines may be produced during vulcanization. The sulfur vulcanization system is highly adjustable and adaptable to different processing conditions.
2. Physical properties of rubber
The physical properties of the EPDM reclaimed rubber peroxide vulcanizate: R-EPDM vulcanizate vulcanized with peroxide has good heat resistance, good resilience, small compression set, good electrical insulation, and stable color of the vulcanizate. Advantages such as good performance, less possibility of electrical leakage during use, low metal corrosion, low extractive content in the medium; in addition, the peroxy vulcanizate has poor tearing performance, low tensile strength, and wear resistance Relatively poor.
The physical properties of EPDM reclaimed rubber sulfur vulcanizate: After the EPDM reclaimed rubber is vulcanized with sulfur, the vulcanized rubber has good tear resistance, especially hot tear performance, high tensile strength, and good wear resistance; EPDM sulfur Vulcanizates have relatively poor heat resistance, resilience, and electrical insulation, and are more likely to have compression set, metal corrosiveness, and rubber frosting, and vulcanizates have poor color stability.
3. Significance of combined use of peroxide and sulfur
In the production of EPDM reclaimed rubber products, many manufacturers use peroxide and sulfur (sulfur-accelerator system) together. When the two vulcanization systems account for a large proportion, the sulfur crosslinks in the rubber compound and CC crosslinks The ratio of the linkage is high, so that the rubber has better tear resistance and fatigue resistance. The vulcanized rubber has higher tensile strength and elongation at break, aging resistance, and the rubber compression permanent deformation and pure peroxide. The physical vulcanization system is slightly worse than that.
EPDM reclaimed rubber is currently the mainstream raw material to reduce the raw material cost of EPDM rubber products on the market. Choosing a suitable vulcanization system can further optimize the quality of the finished product while reducing the cost. The follow-up editor will discuss related issues with you in detail.
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