Figs. 1 and 2 show the results for scorch time, t2 and
cure time, t90 for bamboo fibre reinforced natural rubber
composites with and without bonding agents. It can beseen that both properties decrease with increasing filler
loading. The trend might be due to the longer time the
rubber composites remain on the mill during mixing.
According to Geethamma et al. [13], as the filler loading
increases, the incorporation time of filler into rubber
matrix also increases and consequently generates more
heat due to additional friction. The Mooney scorch time,
t5 obtained from the Mooney viscometer at 120°C also
exhibit a similar trend (Fig. 3). However, at similar filler
loading, the scorch and cure times of composites with
bonding agent are shorter than for the composites without
bonding agent, which is attributed to adhesion
between the fibre and the rubber matrix being enhanced
and more energy needed to incorporate the fibres due to
increased viscosity.