What are crosslinking chemicals?
Crosslinking chemicals are reactive additives that are used in Compounds from Rubber to be used during the Vulcanisation chemical bridges between the Polymer chains to produce. This cross-linking turns a plastically deformable material into an elastic, dimensionally stable material with significantly improved mechanical, thermal and chemical properties.
Function of crosslinking chemicals
During the crosslinking process, the crosslinking chemicals react with the functional groups of the polymer chains. The type of crosslinking significantly determines the final properties:
- Sulphur crosslinking - Linking the polymer chains using chains of up to eight sulphur atoms - a classic process for many elastomers such as NR, SBR or EPDM; results in good elasticity and dynamic load capacity
- Peroxide crosslinking - Direct connection between individual carbon atoms of the polymer chains - for high temperature resistance and good ageing resistance, e.g. in the case of FKM or heat-resistant EPDM-Compounds
- Metal oxide crosslinking - Formation of metal complexes with functional groups of the polymer chains - typically with CR or IIR, often with zinc oxide
- Silane crosslinking - Connection of the polymer chains through Si-O-Si chains - for moisture-reactive polymers such as polyolefin or EPDM-based systems
- Azo and urea compounds - Special crosslinkers for individual properties
Influence on the material properties
The type and quantity of crosslinking chemicals influence Hardness, elasticity, Tensile strength, elongation at break, compression set, hysteresis as well as temperature and media resistance. Too low a cross-linking density can lead to reduced mechanical properties, while too high a cross-linking density makes the material brittle.