The Smallest Ingredient Can Make Something Great. We are certain PEX-b is the best form of crosslinking

The crosslinking of polyethylenes for cables and pipes, using peroxide, silanes or irradiation, has been a standard process for decades. When crosslinking polyethylenes with silanes - the PEX-b procedure - these almost literally represent the salt in the soup - except, though just as important, they are considerably more versatile.

There is no doubt that the use of even small amounts of silane guarantees the quick and cost-effective crosslinking of polyethylenes. Only then is the mechanical and thermal stability of pipes and cables made possible. Less known is just how important the perfect match of silane to polyethylene is for the end product.

Market leader in the field of speciality chemical solutions, Evonik, with its brand Dynasylan^®, is the only silane manufacturer in the world to develop, test and produce in collaboration with its customers silane products designed specially for the customer. These customers currently have access to almost one hundred different products of the brand family Dynasylan^® SILFIN. Furthermore, in many countries Dynasylan^® products have also been officially authorized for use in drinking water pipes.

In the last 30 years, silane crosslinking (PEX-b) has proven to be the most economic way to crosslink polyethylene for cables and pipes. Against other crosslinking technologies, such as peroxide (PEX-a) or radiation (PEX-c) curing, crosslinking by means of organofunctional silanes has the following major advantages:

• Well-established and economical process
• Environmentally-friendly technology
• Crosslinking occurs outside the extruder
• Low investment costs
• High flexibility due to a broader processing window
• High throughput rates
• Small amounts of silane result in excellent properties

The crucial difference between silane technology and peroxide or electron beam processes is that the polymer is chemically modified in the first step. Generally, this reaction is carried out by grafting a vinylsilane onto the polymer chain with small amounts of peroxide. After grafting, the polymer is still thermoplastic and can be used in many ways. Crosslinking itself always takes place outside the extruder and is initiated by water, for example as water bath, steam chamber, or at ambient conditions. Silane technology has proven to be the most economical way to crosslink polyethylene.