An In Situ Method for Deciphering Nanomechanical Behavior in Elastomer Nanocomposites under Large Deformation

The optimization of mechanical properties and the expansion of applications for elastomers such as rubber and hydrogels have been longstanding focal points in materials science research. This study investigates the mechanical behavior and deformation mechanisms of elastomer nanocomposites under large strains, focusing on the reinforcing effect of nanofillers such as carbon black (CB) and carbon nanotube (CNT). Using a nanoscale visualization method based on atomic force microscopy (AFM) integrated with a microprecision-controlled uniaxial tensile device, we achieved in situ tracking of microscopic deformation behavior and stress distribution within a 200% strain range. The study reveals that the stress transmission and distribution mechanisms in nanocomposites vary significantly with the type and morphology of the nanofillers. CB composites form stress chains under strain, which interact with CB fillers to create a stress network structure, leading to significant reinforcement. In contrast, CNT composites exhibit a different mechanism due to their high aspect ratio and orientation behavior. These findings provide crucial insights into the design of nanocomposite rubber materials with tailored mechanical properties, contributing to advancements in biosensors, carbon-neutral technologies, and aerospace engineering.