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Surface photooxidation of polypropylene-based photovoltaic backsheets: A comprehensive spectroscopic investigation
•Studied PP backsheets show general resistance to oxidative degradation with UV aging.•Functional group analysis revealed greatest UV effect on ester and lactone quantity.•Fragmentation testing shows low cracking propensity for co-extruded PP backsheets.•No properties examined showed signs of catast...
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Published in: | Polymer degradation and stability 2025-02, Vol.232, Article 111132 |
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Main Authors: | , , , , , , |
Format: | Article |
Language: | English |
Subjects: | |
Online Access: | Get full text |
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Summary: | •Studied PP backsheets show general resistance to oxidative degradation with UV aging.•Functional group analysis revealed greatest UV effect on ester and lactone quantity.•Fragmentation testing shows low cracking propensity for co-extruded PP backsheets.•No properties examined showed signs of catastrophic degradation or failure.•The greatest chemical and physical changes occurred in initial phase of exposure.
The prospect of cost reduction, enhanced performance, and improved sustainability has been driving innovation in the development of new backsheet materials for photovoltaic (PV) modules. Among the materials of interest, polypropylene (PP) has emerged as a promising alternative to fluoropolymer backsheets. As backsheets serve as a barrier providing electrical insulation and protection for the sensitive electrical components of PV modules, comprehensive understanding of the durability of PP-based backsheets is essential to ensure module reliability in the field.
In this study, free-standing coextruded PP backsheets were subjected to artificial weathering to elucidate the degradation behavior. The UV exposure was performed on the NIST Simulated Photodegradation via High Energy Radiant Exposure (SPHERE) under three environmental conditions: 75 °C and 50 % relative humidity (RH), 75 °C and 20 % RH, and 65 °C and 20 % RH. The total UV dose (295 nm to 400 nm) for each film was ≈1710 MJ/m2, or ≈50 years in Arizona, assuming 10 % albedo. Chemical, optical, and physical changes were monitored throughout exposure. Peak-resolving analysis was applied to attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectra to obtain functional group concentrations with respect to exposure. The greatest chemical and physical changes are seen after initial exposure (100 MJ/m2 to 220 MJ/m2), followed by a saturation point. Spectroscopic results indicate minor accumulation of oxidation products and additive migration. Raman spectroscopy showed a slight increase in crystallinity of the surface layers of the backsheets. Mechanical testing revealed low cracking propensity, with shallow cracks occurring under high strains. |
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ISSN: | 0141-3910 |
DOI: | 10.1016/j.polymdegradstab.2024.111132 |