Quantitative Metathetic Degradation of Rubbers and Sulfur Crosslinked Rubbers—Including Tires

Abstract

Abstract Unsaturated polymers can be converted metathetically to fragments of low molecular weight by adding monoolefins. Since the scission of the polymer backbone always occurs at the double bonds, analysis of the degradation products enables a conclusion about the polymer microstructure. Our earlier works have shown that in case of polybutadienes and styrene-butadiene copolymers, the catalyst system “tungsten hexachloride/tetraalkyltin/diethylether” allows a selective degradation and detailed determination of the microstructure. On the other hand complete degradation of polyisoprenes and sulfur crosslinked rubbers failed using conventional metathesis catalysts. Our latest investigations show that using stable transition metal carbenes as catalysts, degradation of polyisoprenes and sulfur-crosslinked rubbers (including tires) proceeds quantitatively. This opens up a method of microstructure determination of crosslinked rubbers, including tires. Results obtained using well denned transition metal carbenes will be compared with those gained employing conventional catalyst systems.