Natural rubber/carbon black/carbon nanotubes composites prepared through ultrasonic assisted latex mixing process

Carbon black (CB) and carbon nanotubes (CNTs) filled natural rubber (NR) composites were prepared through an ultrasonic assisted latex mixing process. Carbon nanotubes were dispersed into NR latex by ultrasonic irradiation and then the mixed latex were co-coagulated to obtain the CNTs/NR masterbatch. The structure and properties of the composites were characterised. The results show that the ultrasonic assisted latex mixing process disperses CNTs more uniformly in the matrix than the conventional mixing methods. The well dispersed CNTs and CB exhibited a synergistic reinforcing effect. When the weight ratio of CB/CNTs was 20∶5 (parts per hundred of rubber), the mechanical properties reached the maximum. Dynamical mechanical analysis revealed that with increasing CNT contents, the elastic modulus of composites at room temperature increased, while the maximum loss tangent decreased. Dynamic rheological measurement showed the storage modulus and complex viscosity of rubber composites increased and the shear thinning index decreased with increasing CNT contents.