Results and discussion
3.1. Curing characteristics
Figs. 1–3 show the effect of chitosan loading on the
curing characteristics of chitosan-filled rubber compounds
as determined with a Monsanto Rheometer. It can be
observed from Figs. 1 and 2 that there is a significant
decrease in scorch and cure times with the addition of
chitosan in all three types of rubber, and the values further
decrease as chitosan loading increases. The observed
reduction in scorch and cure times is an indication of the
enhancement of the cure rate. In most cases, cure
enhancement is a consequence of filler parameters such as
surface area, surface reactivity, particle size, moisture
content and the presence of metal oxides [18]. However, in
this study, the cure enhancement was possibly attributed to
the formation of bonds due to the interaction between the
chitosan functional groups (–OH and –NH2 groups in chitosan)
and the compounding additives. Such observation
has been reported by El-Helfian et al. [19] in their studies of
chitosan and agar.