Study of the Structure and Elastic Properties of Ethylene‒Propylene‒Diene Elastomers by Atomic Force Microscopy

The structure and local elastic properties of synthetic ethylene‒propylene‒diene elastomers, unplasticized and plasticized with paraffin oil during synthesis, are studied by atomic force microscopy. The elastomers are subjected to high-temperature vulcanization by a sulfur-containing system with varying sulfur concentration. For vulcanizates of different degrees of crosslinking a quantitative comparative analysis of macroscopic elastic moduli measured in uniaxial tension and local elastic moduli determined by the nanoindentation technique based on atomic force microscopy is performed. To quantify the elastic modulus through the nanoindentation procedure a complete calibration of the system is done and elements of probe apex geometry characterization are implemented using the piecewise linear interpolation approach. The Sneddon model is used as a contact mechanics model to quantify the values of the elastic modulus.