The performance of silicone rubber products is critically dependent on the choice of crosslinking agent. Among the various curing chemistries available, peroxide crosslinking is widely favored for its ability to impart excellent thermal stability and good mechanical properties to silicone elastomers. NINGBO INNO PHARMCHEM CO.,LTD. understands that selecting the right peroxide agent is a crucial decision for manufacturers. This guide provides insights into key considerations when choosing a crosslinking agent for silicone rubber applications.

The primary function of a crosslinking agent is to create a three-dimensional network within the silicone polymer, transforming a soft, pliable material into a strong, elastic rubber. Peroxide crosslinking agents operate through a free-radical mechanism, initiated by heat. The effectiveness of a peroxide agent is typically measured by its decomposition temperature range and the radicals it generates, which directly influence the curing speed, scorch safety, and the final properties of the silicone rubber. For instance, formulations based on 2,5-Dimethyl-2,5-di(tert-butylperoxy)hexane are known for their bifunctional nature, meaning they can create a dense network of crosslinks efficiently.

When selecting a peroxide crosslinking agent, two critical factors should be evaluated: scorch safety and thermal stability. Scorch safety refers to the compound's resistance to premature curing during processing. A higher degree of scorch safety provides manufacturers with a more extended processing window, allowing for easier molding and extrusion without the risk of the material becoming unworkable. This is achieved by peroxides that decompose more slowly at typical processing temperatures, delaying the onset of curing. For example, a safe processing temperature of 135°C with a long scorch time (ts2 > 20 minutes) is highly desirable.

Thermal stability is equally important, especially for silicone rubber products intended for use in high-temperature environments. The crosslinks formed by the peroxide agent must be robust enough to withstand prolonged exposure to heat without degradation. Peroxide-cured silicones generally offer excellent thermal stability, maintaining their mechanical properties and dimensional integrity at temperatures where other elastomers might fail. The typical crosslinking temperature, for example, around 175°C, indicates the temperature at which the peroxide efficiently catalyzes the formation of these durable crosslinks, ensuring long-term performance.

Other considerations include the physical form of the peroxide (e.g., paste, liquid, powder), its active oxygen content, and its compatibility with other additives in the silicone compound. NINGBO INNO PHARMCHEM CO.,LTD. offers a range of silicone rubber crosslinking agents tailored to meet diverse application needs. Our expertise in chemical auxiliaries and rubber additives ensures that our clients receive products that not only meet but exceed performance expectations. By carefully considering scorch safety, thermal stability, and specific application requirements, manufacturers can confidently select the optimal peroxide crosslinking agent to achieve superior silicone rubber products.