Nanoscale physics

PV encapsulant material mechanical properties     (peculiarities and their microscopic mechanisms)
Kislyuk V.V.1, Shyvaniuk V.M.1, Trachevskij V.V.2, Ostapyuk S.M.3, Kotrechko S.O.1
1 G.V.Kurdyumov Institute of Metal Physics, NAS of Ukraine, 36 Academician Vernadsky Boulevard, UA-03142 Kyiv, Ukraine.
E-mail: viktor.kislyuk@gmail.com
2 Technical Center, NAS of Ukraine, Pokrovsʹka St., 13, UA-04070, Kyiv, Ukraine.
3 Institute of Macromolecular Chemistry, NAS of Ukraine, Kharkivsʹke shose St., 48, UA-02160 Kyiv Ukraine.

The photovoltaic (PV) module encapsulant material (which is ethylene vinyl acetate (EVA) in ca. 80% cases) is subjected to the complex cumulative impact of severe factors destroying (while its operation) its mechanical integrity due to dramatic transformations in its content and structure, which is to be taken into account for predicting service life of a material [1,2]. A detailed analysis is proposed for the explanation of the mechanical properties of EVA films exposed to various thermo-mechanical loads and ultraviolet irradiation. The «true stress-true strains» diagrams (the only correct representation for these materials [3]) are studied in comparison with spectra of nuclear magnetic resonance (NMR) and infrared absorption (IR) that contain features characteristic for viscous component of the polymer structure. 
A microscopic model is developed for the underlying nanoscale processes to describe the macro- behavior of the EVA films both as prepared and deteriorated after the exposal to the above factors.

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2.	Kotrechko S. Embrittlement of RPV metal under long-term irradiation: state of- the-art // Structural Integrity Procedia – 2018. – 13. – P. 11–21.
3.	Kislyuk V.V., Shyvaniuk V.M., Trachevskij V.V., Polushkin Yu.O., Kotrechko. S.O. Novel approach to analysis of PV encapsulant material properties // Abstract book of Int. workshop on “Functional materials for innovative Energy”, Kyiv. – 2021. – P 48.