国外专利EVA--Titre du document.docVIP

Titre du document / Document title Factors that affect the EVA encapsulant discoloration rate upon accelerated exposure Auteur(s) / Author(s) PERN?F. J. (1) ; Affiliation(s) du ou des auteurs / Author(s) Affiliation(s) (1) Measurements and Characterization Branch, Photovoltaics Division, National Renewable Energy Laboratory, 1617 Cole Blvd., Golden, CO 80401, ETATS-UNIS Résumé / Abstract Copyright (c) 1996 Elsevier Science B.V. All rights reserved. Several factors that affect the discoloration rate of the ethylene-vinyl acetate (EVA) copolymer encapsulants used in crystalline-Si photovoltaic (PV) modules upon accelerated exposure have been investigated primarily by employing UV-visible spectrophotometry, spectrocolorimetry, and fluorescence analysis. A variety of film samples including the two typical (unprimed) EVA formulations, A9918 and 15295, were studied. The films were laminated, cured, and exposed to either a concentrated 1-kW Xe or an enhanced-UV light source. The results indicate that the extent of EVA discoloration can be affected by factors of two general categories: chemical and physical. In the chemical category, the degradative factors include (1) EVA formulation, (2) presence and concentration of curing-generated, UV-excitable chromophores that depend on the type of curing agent used, (3) loss rate of the UV absorber, Cyasorb UV 531TM, (4) curing agent and curing conditions, and (5) photobleaching reactions due to diffusion of air into the laminated films. In the physical category, the factors involve (6) UV light intensity, (7) UV-filtering effect of glass superstrates, (8) gas permeability of polymeric superstrates, (9) film thickness, and (10) lamination?delamination (maybe chemical and/or mechanical effect, too). Photodecomposition of the Cyasorb was first verified in cyclohexane solutions and then in Elvax 150TM (EVX) films (the copolymer without any additives and curing agent). Cyasorb decomposition rates in cyclohexane solutions are exponenti