reported by Ismail et al. [7]. Also, Joly et al. [11] reported
that the addition of inorganic components leads to property
changes physically and mechanically due to different
filler morphology such as particle size, structure, surface
reactivity and degree of dispersion. As demonstrated in a
previous study [5], the porous structure in OPA allowed the
rubber chain to penetrate in and form bound rubber.
However, this is only achievable when a low loading of OPA
is used due to hydrophilic properties of OPA which tends to
agglomerate. Therefore, the OPA could be fully wetted by
the rubber matrix and enable stress transfer from the NR
matrix. As a result, it exhibited comparable strength and
elongation at break to the carbon black-filled vulcanizates.
Figs. 2 and 3 individually present the impact of various
fillers on tensile modulus (M100 and M300) and hardness of