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Crack-resistant pipes

Water is our number one nutrient. If drinking water is to reach private homes safely, the pipes that carry it have to meet high standards of quality. An Evonik crosslinker makes pipes robust, resistant to cracking, lightweight, and long-lasting.

Even though just four percent of Germany’s drinking water is actually drunk, the water still has to meet high standards of quality. After all, drinking water is our number one nutrient. And whether water is transported safely from providers to private households is largely dependent on the quality of the pipes.

One material used for drinking-water pipes is polyethylene, an extremely dense plastic. If these pipes are to remain stable underground at high pressures and temperatures, the plastic has to be crosslinked. Its molecules, in other words, have to undergo a chemical reaction that links them to each other to form a three-dimensional network. It sounds complicated, but to put it simply, the process makes the pipes harder and tougher, and raises their melting point.

Pipe manufacturers use a number of different methods to achieve this. While some irradiate the plastic, others use peroxides to form strong, short carbon-carbon single bonds between the polyethylene chains. Manufacturers who choose Dynasylan® SILFIN 50 from Evonik take the process a step further. Vinylsilane is a chemical compound that creates relatively large gaps between polyethylene chains, which makes the polymer more flexible and elastic.

To make that easier to understand, it helps to picture a bridge: the links that peroxides produce are like concrete overpasses—rigid and strong, the shortest distance between two points—but the connections made by Dynasylan® SILFIN 50 move as easily as rope bridges. In terms of a drinking-water pipe, that means that the material can expand more under pressure, it is more resistant to cracking, and its relaxed structure makes it lighter too—effects that can be achieved in 100 kilograms of polymer by mixing in Dynasylan® SILFIN 50 at an approximate concentration of just 1.5 percent.