A Novel Reactive Hindered Amine Light Stabilizer for In Situ Grafting in POE Photovoltaic Encapsulation Films during Cross-Linking

Abstract

Conventional hindered amine light stabilizers (HALS) often fail to meet the antiphotoaging requirements for Polyolefin Elastomer (POE) photovoltaic encapsulation films under harsh environmental conditions due to migration and leaching. In this research, a novel reactive hindered amine light stabilizer (rHALS) for in situ grafting during cross-linking of POE photovoltaic encapsulation films was synthesized and its performance in enhancing the photoaging resistance of POE encapsulation films was investigated. First, the successful synthesis of rHALS was confirmed by Fourier Transform Infrared Spectroscopy (FTIR) and H Nuclear Magnetic Resonance spectroscopy (1H NMR). Subsequently, rHALS was employed to enhance the photoaging resistance of POE encapsulation films. FTIR analysis after photoaging revealed that rHALS effectively reduced the formation of carbonyl species (with a 42% reduction in carbonyl peak area), indicating significant inhibition of photoaging. Rheological studies further demonstrated that rHALS more effectively mitigated the decline in the storage modulus induced by photoaging compared to conventional HALS with similar structures, indicating enhanced resistance to cross-linked network degradation and thus enhanced antiphotoaging performance. Finally, the mechanism responsible for the enhanced antiphotoaging property of rHALS was investigated. Both FTIR and X-ray photoelectron spectroscopy (XPS) results confirmed that rHALS was grafted onto the POE backbone during cross-linking. This chemical bonding rendered rHALS more resistant to migration and leaching. XPS analysis revealed that after prolonged thermal treatment, the surface nitrogen content (indicative of HALS leaching) increased by 33% in POE films using conventional HALS, whereas those with rHALS showed only a 4% increase. These results demonstrate that rHALS possesses a stronger antiphotoaging performance due to its significantly reduced migration and leaching. This study offers a new technical strategy for designing POE encapsulation films with enhanced antiphotoaging properties, thereby broadening their potential applications under severe service conditions.