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Eumelanin for Nature‐Inspired UV‐Absorption Enhancement of Plastics
摘要： In the human body, the black-brown biopigment eumelanin blocks the harmful ultraviolet (UV) radiation. In the plastics industry, additives are often added to polymers to increase their UV-absorption properties. We herein report an assessment of the biopigment eumelanin as a nature-inspired additive for plastics to enhance their UV-absorption. Since eumelanin is produced by natural sources and is non-toxic, it is an interesting candidate in the field of sustainable plastic additives. In this work, eumelanin-including films of commercial ethylene-vinyl acetate copolymer (EVA), a plastic used for packaging applications, were obtained by melt-compounding and compression molding. The biopigment dispersion in the films was improved by means of the Melanin Free Acid treatment (MFA). It was observed that eumelanin amounts as low as 0.8% wt. cause an increase of the UV absorption, up to one order of magnitude in the UVA range. We also evaluated the effect of eumelanin on the thermal and photostability of the films: the biopigment proved to be double-edged, working both as UV-absorption enhancer and photo-prooxidant, as thermogravimetric analysis (TGA) and infrared (IR) spectroscopy revealed.
关键词： Eumelanin,Packaging,Melanin Free Acid,UV-absorbers,Ethylene-vinyl acetate copolymer,UV-aging
更新于2025-10-22 19:40:53
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[IEEE 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Chicago, IL, USA (2019.6.16-2019.6.21)] 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Determination of Crystallinity and Thermal Stability of Newly Developed Thermoplastic Polyolefin Encapsulant for the c-Si PV Module Application
摘要： Thermoplastic polyolefin (TPO) is a newly developed non-crosslinking encapsulant for the crystalline silicon PV modules lamination. The degree of crystallinity and thermal stability of TPO have been studied and compared with the most commonly used ethylene vinyl acetate (EVA) copolymer encapsulant. The peak melting point and the degree of crystallinity have been determined with the help of differential scanning calorimeter (DSC) analysis. The crystallinity of both the encapsulant also studied with x-ray diffraction. DSC results show that there is no crosslinking reaction involved in the TPO encapsulant. Thermogravimetric analysis (TGA) is done to determine the thermal stability and thermal decomposition onset temperature. This work will help in understanding the thermal behavior and degree of crystallinity of newly developed TPO encapsulant, which can also potentially replace the EVA encapsulant for the PV module application.
关键词： encapsulant,polyolefin,crystallinity,thermal stability,ethylene vinyl acetate,photovoltaics
更新于2025-09-23 15:21:01
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Early-stage identification of encapsulants photobleaching and discoloration in crystalline silicon photovoltaic module laminates
摘要： Commercially different variants of ethylene-vinyl acetate (EVA) encapsulants are available in the photovoltaic (PV) market. Photobleaching and discoloration are the two most commonly observed phenomena, and their initiation may be different for different encapsulants. To investigate the EVA encapsulant photobleaching and discoloration, solar cell laminates having different EVA films (UV-transparent [T], UV-cut [C], and combination of the two [TC]) were tested in Xenon test chamber. High temperatures are created in the laminates during the aging tests by using a thick insulation layer behind the backsheet. The UV fluorescence images and grayscale profile show clear signs of photobleaching and discoloration. It is found that the oxygen diffusion coefficient of the T sample is four and nine times slower than the TC and C samples, respectively, in the photobleached region. Fluorescence imaging and spectra and Raman spectra were taken before and after the accelerated test and indicate that discoloration causing fluorophores generation is higher after the photobleached region for transparent and combined EVAs, whereas higher at the center for UV-cut EVA laminates. A colorimeter was used to measure the Yellowness Index of the samples before and after the accelerated aging test. This work will help in the early detection of photobleaching and discoloration of any encapsulant used in the PV modules. This method will also help to study the behavior of encapsulants in different climatic conditions like hot, cold, dry, humid, and their combinations by simulating the same in an accelerated weathering chamber by using the different insulation thickness.
关键词： fluorophores,discoloration,photovoltaic module,photobleaching,ethylene-vinyl-acetate encapsulant
更新于2025-09-23 15:19:57
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[IEEE 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Chicago, IL, USA (2019.6.16-2019.6.21)] 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Determination of Crystallinity, Composition, and Thermal stability of Ethylene Vinyl Acetate Encapsulant used for PV Module Lamination
摘要： Ethylene Vinyl Acetate (EVA) Copolymer is a most commonly used encapsulant for PV module lamination. Using cured and uncured EVA, several key characteristics of EVA have been determined. The glass transition temperature, peak melting point, degree of crystallinity has been determined with the help of Differential scanning calorimeter (DSC) analysis. Thermogravimetric analysis (TGA) is done to determine the Vinyl Acetate content and the thermal stability based on degradation onset temperature. This work will help to understand the thermal behavior and initial VA content estimation of the unknown grade of EVA encapsulant, which greatly affects the final module reliability.
关键词： encapsulant,crystallinity,thermal stability,ethylene vinyl acetate,photovoltaics
更新于2025-09-19 17:13:59
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Newly developed thermoplastic polyolefin encapsulant–A potential candidate for crystalline silicon photovoltaic modules encapsulation
摘要： Thermoplastic polyolefin (TPO) is a newly developed non-crosslinking material for photovoltaic (PV) module lamination as an alternative to ethylene–vinyl-acetate (EVA) encapsulant. This article assesses its applicability as an encapsulant material. We report the results of various characterization tests for discoloration, optical, and thermal properties degradation before and after the UV accelerated test. To evaluate its weathering stability, the UV-365 acceleration test has been conducted on the glass to glass TPO laminate, with EVA as a benchmark. In 50 days of weatherability tests, the transmittance of EVA significantly reduced while TPO remained almost unchanged. The discoloration of TPO is around nine times slower than that of EVA. The analytical tools like Raman spectroscopy, fluorescent imaging, and spectra have been used to assess the degradation behavior, which indicates a clear difference between EVA and TPO based encapsulant. Thermal properties (glass and melt transitions) of TPO and EVA have been studied through heat-cool-heat cycle testing by differential scanning calorimeter (DSC). This test confirmed that TPO thermal properties remain almost unchanged, whereas EVA shows significant changes after 50 days of UV exposure. In the thermogravimetry analysis (TGA) results, we found that TPO is stable till a significantly higher temperature than EVA. Additionally, the 180° peel adhesion test suggests that TPO has a higher adhesion strength than EVA. This work will help in understanding the applicability of newly developed non-crosslinking TPO as a potential replacement for EVA for the PV modules.
关键词： Thermoplastic polyolefin,Photovoltaic module,Encapsulant,Non-crosslinking,Ethylene-vinyl-acetate
更新于2025-09-16 10:30:52
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Ultraviolet to visible down conversion of SiO2–Ce3+, Tb3+ nanospheres-poly-EVA films for solar cell application
摘要： Despite the many advantages which the conventional crystalline silicon solar cells have over other forms of renewable energy sources, they still have major drawbacks (energy loss) limiting their performance. One of the main reasons for energy loss is the ineffective utilization of short wavelength photons, especially within the UV region. The efficiency of the c-Si solar cell device can be improved by depositing the phosphor nanoparticle on top of the devise to capture and convert to capture and covert the UV photons from sunlight to visible or near infraded photons by a downcoversion process. Therefore, we have prepared and investigated luminescent and optical properties of downconverting nanophosphors composed of SiO2 co-doped with Ce and Tb. The dominant photoluminescence emission peak was observed at 544 nm and it was attributed to the 5D4 →7F5 transition of Tb3+. The phosphors synthesised were incorporated into poly poly-ethylene vinyl acetate (poly-EVA) films which were later overlaid on a commercial silicon solar cell to and its photocurrent efficiency were measured. The phosphor films recorded a significantly good transmittance (≥76%) and also displayed a UV absorption capacity compared to that of the plain poly-EVA film. Some of the films made from different concentrations of Ce and Tb, recorded an increase in the photocurrent efficiency when deposited on the solar cell, while other compositions recorded marginal decreases compared to that of the plain EVA film.
关键词： Downcoversion,Silicon solar cells,Ultraviolet,Photocurrent,Poly-ethylene vinyl acetate,Photoluminescence
更新于2025-09-16 10:30:52
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Dielectric and thermal behavior of 0.75BiFeO3-0.25BaTiO3 filled ethylene vinyl acetate Composites
摘要： Bismuth ferrite-Barium Titanate (BFO-BT) filled ethylene-vinyl acetate copolymer (EVA) composites have been processed by solution casting technique followed by compression molding. The effects of BFO-BT on structural, thermal and dielectric behaviour of the composites have been investigated using X-ray diffraction, field emission scanning electron microscopy, thermal analysis (DSC, TGA) and impedance analyser. As analysed by XRD and DSC analyses, with increase in BFO-BT content the crystallinity of EVA matrix decreases. BFO-BT has great effect on higher thermal stability of the composites. EVA/ BFO-BT composites exhibit significantly enhanced relative dielectric permittivity (εr =182) near the percolation limit of about 30 phr BFO-BT loading at 25° C and 1kHz frequency. With 30 phr BFO-BT loading, the dielectric loss of the composite shows only an approximately 2-fold increase i.e., from 0.04 to 0.091. The capacitance and resistance of grains is found from the exploratory Nyquist plots with the assistance of an electrical circuit. A cautious examination of the experimental complex impedance plots and model fitted plots is contemplated which fulfilled the precision of the information tentatively. With enhanced dielectric properties and thermal stability, the BFO-BT filled EVA composite system can be used for solar cells and energy saving devices.
关键词： Composites,Nyquist plots,Dielectric,Conductivity,Ethylene Vinyl Acetate,Bismuth Ferrite-Barium Titanate
更新于2025-09-12 10:27:22