Quantitative characterization of interfacial properties of carbon black/elastomer nanocomposites and mechanism exploration on their interfacial interaction

Carbon black (CB) is widely used as a good reinforcing filler in rubber industry. Due to the complex cluster structure of CB aggregate, it is difficult to clearly visualize its topological morphology and interfacial properties at nanoscale of CB/rubber composites. Thus, the good reinforcing mechanism of CB on rubber is still not fully understood. In this study, the surface topography structure of CB with different specific surface area (SSA) were characterized and their surface roughness were quantified using atomic force microscope (AFM). By using low content of CB and applying strong shear force to minimize the size of CB aggregate, the clear visualization of the bound rubber around CB aggregate was obtained using Quantitative Nanomechanical Mapping (QNM) technique of AFM (AFM-QNM). For the first time, the quantitative characterization of interfacial thickness and nano-mechanical modulus of CB/rubber composites were realized by AFM-QNM. Results show that the higher SSA of CB is mainly attributed to the higher surface roughness caused by the more complex topological structure of CB. And the higher surface roughness results in the higher interfacial thickness and Young's modulus at the nanoscale. Why CB with slightly smaller diameter shows largely increased reinforcing effect on rubber matrix is well explained.