Abstract
This paper presents a sight about the chemical structure deformation of poly (ethylene-co-vinyl acetate) (EVA) samples according to the change ratio of rate constant values. Spectroscopy kinetics fluorescence curves are fitted for two characteristic wavelength domains of fluorescent intensities. The short wavelengths (320-400 nm) domain show spectra overlapping, while at long wavelengths (400-800 nm) domain spectra are arranged in regular for each specific accelerated aging time. The ratio of kinetics rate constant at long wavelengths to kinetics rate constant of short wavelengths is the criterion of the degree chemical structure deformation. Molar extrinsic coefficient relies on the chemical structure change. Through absorbance measurement, EVA samples have been classified into two groups. Presence of Cyasorb additive is the key point of the ranking. The effect of three different accelerated aging of dry (115 oC), damp (85% moisture, 85 oC), and irradiated (UV, 65 oC) aging have been considered for two samples of each group over different aging time. Spectroscopy of absorbance and fluorescent for aged samples have been discussed. In general, Cyasorb adding causes higher chemical structure deformation for the EVA sample. The most effective factor is the damp aging and the less one is the UV irradiation aging, while the biggest chemical structure change of Cyasorb-free sample is produced by damp aging and the less by dry heat.
Highlights
Earlier, ethylene-vinyl acetate EVA did not have the best combination properties, yet it was chosen for economic reasons
The noteworthy thing is not all the samples have this type of UV absorber, where absorbance spectra of S4 and S6 do not show the characteristic spectrum of this additive type
Cyasorb additive progressively suffers from severe degradation by the aging time of dry heat at 115 oC
Summary
Ethylene-vinyl acetate EVA did not have the best combination properties, yet it was chosen for economic reasons (that is, its being inexpensive). It is so helpful to break up the crystallites of the polyethylene by adding a rate of about 33wt% of poly vinyl acetate to produce a copolymer of EVA of high optical transmission and a low Tg [3]. That led to produce newer EVA formulations of better antioxidants and ultraviolet UV absorbers for the same base resin, to overcome this problem of yellowing over a 20-30 year lifetime of a module [6]. Many factors have been found to produce this discoloration which is described by different terms as yellowing, browning, brown cell, amber, and degradation These factors include elevated temperature, UV light, the combination of high temperature and UV light, and effects of module construction. It is found [9], that the optimization and characterization of the EVA are possible by the utilization of the degradation-induced the photoluminescence of the copolymer
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
