Electron Emission as a Tool for Detecting Fracture and Surface Durability of Tensile-Loaded Epoxy Polymers Modified with SiO2 Nanoparticles

Epoxy polymers modified with nanoparticles are increasingly employed due to their enhanced performance in aggressive environments, characterized by mechanical stress, radiation exposure, and extreme temperatures. The mechanical failure of these polymers is attributed to the fracturing of atomic and molecular bonds, that subsequently excites electrons having the capability to be emitted from the nanolayer of the material. The present study demonstrates that the relationship between mechanical loading and electron emission over time serves as an indicator of surface loading and durability. By utilizing the Kinetic Nature of Solid Material Strength (KSMS) theory alongside near-threshold electron emission measurements, the article presents the behavior of epoxy polymers modified with SiO2 nanoparticles under tensile loading. The results indicate that as mechanical load is applied, photoelectron emission (PE) pulses emerge. Notably, the pulse spectrum highest frequency (fmax) correlates with the time of atomic fluctuations (τ), defined by τ = 1/fmax. Furthermore, ultraviolet (UV) irradiation of the nanoparticles prior to mixing with the polymer is shown to influence the parameter of KSMS responsible for local stress concentration. This suggests that PE is connected with the homogeneity of the composite too. The achieved results demonstrate that PE contactless measurements can be used to detect mechanical destruction of the epoxy polymer composite surface nanolayer, as well as to assess its durability and corresponding activation energy. The results presented in the article may contribute to the development of more reliable epoxy polymer composites and durability measurements of their mechanically loaded surface layer or nanofilms.