What is sulphur cross-linking?
Sulphur crosslinking is the most common process for Vulcanisation of elastomers in which sulphur is used as Cross-linking chemical is used. It is the standard process for unsaturated elastomers such as natural rubber (NR), SBR, NBR and other unsaturated gum types.
How does sulfur crosslinking occur?
At temperatures between 140°C and 180°C, the sulphur reacts with the double bonds in the polymer chains of the Rubber. Supported by accelerators and activators (e.g. zinc oxide), sulphur bridges (mono-, di- or polysulphide bridges) are formed between the chains. The type of bridges influences the hardness, flexibility and Heat resistancePolysulphide bridges lead to softer, more elastic material - monosulphide bridges to higher temperature resistance.
Advantages:
- Economical process
- High elasticity
- Properties easily controllable through process control
Disadvantages:
- Low Heat resistance (typically up to +120°C, depending on the recipe)
- Low Ageing- and media resistance (e.g. oils, solvents)
- Not suitable for saturated polymers such as EPDM or FKM
Typical applications:
- Seals, Damping elements, Suspension elements
- Technical rubber parts for construction, industry and transport
- Tyres, tubes, conveyor belts
