DETERMINATION OF CARBON-BLACK FILLERS IN VULCANIZATES OF NATURAL-RUBBER BY METATHESIS DEGRADATION

A method for the determination of carbon black fillers in peroxide vulcanizates or sulfur vulcanizates of natural rubber (NR, cis- 1,4-polyisoprene) by metathesis degradation with 1-octene was developed using the catalyst WCl6-(C2H5)3AlCl3. The carbon black was separated from the reaction mixture by centrifuging and determined by weighing. In this connection, investigations were also performed with the catalyst WCl6-C2H5AlCl2 which was less suitable for filler determination. The rate of degradation of crosslinked NR with (E)-4-octene was measured. Metathesis reactions of 2-methyl'-2-pentene (low-molecular-weight model compound of NR) with 7-tetra-decene showed the importance of double bond shift for the degradation of NR.