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 sulphur cross-linking work?
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