Lanxess showcased its broad range of additives for the rubber processing industry at DKT. These include pre-dispersed chemicals, processing promoters as well as vulcanisation and filler activators. In the spirit of advancing sustainability, the focus was not only on rubber production but also the manufacture of long-lasting rubber products. The lifetime is an important indicator for the performance of rubber products. The S-SBR/BR–silica mixtures used in passenger car tyres, for example, can cause the tread to start “post-vulcanising” during its service life, leading to changes in the molecular network and gradual hardening. Additives such as Perkalink and Vulcuren allow tyre manufacturers to develop and produce mixtures for tyres designed to deliver high performance over their entire service life. On day one of the conference, Dr. Hermann-Josef Weidenhaupt – a specialist in rubber additives at Lanxess – held a presentation entitled “Perkalink 900 – The Smart Solution for Sulfur and Peroxide Crosslinking”, in which he explained the specific qualities of this anti-reversion agent in relation to cross-linking.

Another highlight at the fair was the topic of recycling through devulcanisation. When precursors are recovered from rubber products, the extreme heat in combination with the mechanical or chemical stress break up the polymer chains, leading to a significant deterioration in the mechanical properties. Therefore a special process is required during devulcanisation in which only the sulfur bridges formed during vulcanisation are destroyed. This is based on the lower binding energy of the S–S and C–S bridges (S = sulfur; C = carbon). The mechanical properties remain largely unaffected here. During devulcanisation, it is important that not too many C–C bonds of the polymer backbone are broken. Steps must also be taken to prevent broken C–S and S–S bonds – i.e., radicals – from re-bonding with the sulfur contained in the mixture. The processing agent Aktiplast 79 is used in this final step, effectively blocking the radicals by reacting with them and, in turn, preventing the broken bond from reforming.

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