Fig. 8 shows the storage modulus (G0) as a function of
strain of the PSi-filled NR compounds. Clearly, G0 decreases
with increasing strain amplitude. This is attributed simply
to the disruption of the filler transient network [2,3]. At low
strains where the filler network still exists, the UMS-filled
NR exhibits the highest G0. Apparently, the G0 at low
strain reduces dramatically with increasing degree of
xanthation. This result suggests that the surface treatment
of PSi via the xanthate reaction could successfully reduce