Effect of grafted carbon black on properties of vulcanized natural rubber

To modify carbon black (CB) surface, in situ grafting of natural rubber (NR) onto the CB surface by solid-state method was used to get grafted carbon black (GCB). The vulcanization characters of NR compounds employed CB and GCB were investigated. Crosslinking density of vulcanized NR was measured by equilibrium swelling method. As a result, it was found that GCB could improve both cure rate and crosslinking density. Moreover, the mechanical properties of vulcanized NR filled with GCB were enhanced to a large extent compared with vulcanized NR filled with CB. No Payne Effect was observed in GCB filled NR compounds during dynamic properties testing, indicating that there was no filler network and GCB was dispersed uniformly in NR matrix, which was proved by SEM micrographs. Based on above results, it was considered that the grafting modification weakened filler-filler interaction and enhanced filler-polymer interaction.