Influence of sizes of rubber particles in latex on mechanical properties of natural rubber filled with carbon black

The structures and properties of natural rubber (NR) obtained from latex with small and large rubber particles (SRP and LRP) are obviously different, while carbon black (CB)/SRP or CB/LRP composites have rarely been reported. In this work, SRP and LRP are separated from natural rubber latex (NRL). The properties of obtained NR/CB composites are systematically investigated as a function of SRP and LRP mass ratios. It shows that the nitrogen content of SRP (1.32%) is much higher than that of LRP (0.10%). Mechanical properties increase with the increase of LRP content because plenty of agglomerates exist in SRP/CB composite whereas LRP/CB composite shows a homogeneous dispersion. Furthermore, a possible model is proposed to illustrate the transformations of agglomerates during stretching and dynamic compressing process. This study provides a new perspective for the design of NR materials through the selection of rubber particles in NRL.