Mineral coupling, improved mechanical properties

Improved mechanical properties retention - The durability of the coupling agent mediated mineral-polymer bond is essential to the long term retention of composite properties. Because this interface is the destination for absorbed... 

Silane coupling agents are thus an extremely valuable range of compounds that can effectively and economically improve the adhesive bonding of a polymer to a mineral, giving superior hydrolytic stability and enhanced electrical and mechanical properties in composite materials. 

When speaking of ethylene-propylene elastomer, the term coupling agents indicates silanes. These substances, added in suitable quantities to compounds containing mineral fillers, increase interaction with the polymer thereby improving the final mechanical properties. 

Initially, silanes were used in compounds based on EPM containing calcined clay and which were intended for electrically insulating applications. It was noticed that the insulating properties were improved and stabilised, especially in a moist environment mechanical properties were also improved. The same type of improvement was noted with hydrated alumina. The most suitable coupling agent, with peroxide crosslinking, is vinyl tri( 1-methoxy-ethoxy) silane with sulphur and accelerator crosslinking systems mercaptopropyl trimethoxy silane is recommended. Silanes have recently been made available as masterbatches and can be added directly to mineral fillers.The use of silanes has now extended to non-black compounds for applications other than cables when silicas and other types of filler (aluminium and calcium silicates) are used. 

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