Fig. 9 shows the effect of ALK on the resilience of the
silica-filled NR vulcanisates. Resilience is the ratio of energy released by the recovery from deformation to that required
to produce the deformation [26]. According to Hofmann
[27], and Ignatz-Hoover & To [24], the rebound resilience is enhanced to some extent as the crosslink density rises, and the resilience is related to the flexibility of the molecular
chains; the more flexible the molecular chains, the better
the resilience. The incorporation of ALK into the silica-filled
NR compound enhanced the resilience of the silica-filled NR
vulcanisates. Again, this can be attributed to the functions of
the ALK as an accelerator and filler dispersant which enhances
the total crosslink density, and as a plasticizer which
improves the flexibility of the filled rubber chains.