it is evident that the increment or decrement in the
values of flex temperature is marginal with RR content. Thus, the
incorporation of RR into fresh NR–PBR does not affect the low temperature flexibility of the vulcanizates in its storage modulus region. This is due to the fact that low temperature flexibility is
affected if the molecular structure of the network contains unsubstituted long chain, which ultimately enhances the low temperature flexibility. In our present study, it is clear that the
incorporation of RR into NR–PBR blend system, although it improves the mechanical property of the blend vulcanizates, does
not improve the low temperature flexibility. This indicates that
the network structure of RR is very much similar to that of the pure
NR–PBR system. Here RR is obtained from the tire tread, which also
contains NR. Thus, due to structural similarity in the back bone, the
low temperature flexibility is not observed