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Title: Review of the photothermal stability of EVA pottants: Effects of formulation on the discoloration rate and mitigation methods

Abstract

Results from extensive studies of the commercial ethylene vinyl acetate (EVA) formulations show that the UV absorber and curing-generated UV-excitable, {alpha},{beta}-unsaturated carbonyl chromophores facilitate the EVA discoloration, which is further enhanced by curing-generated acetic acid and probably residual peroxide curing agent also. Formation and concentration of the UV-excitable chromophores are substantially promoted by the antioxidant, Naugard P. The discoloration rate is greater under higher UV light intensity and temperatures. Heating in the dark at elevated temperatures (e.g., 85&hthinsp;{degree}C) in the air for {approximately}200 days only results in light yellowing. The discoloration reactions compete with photobleaching reactions, which destroy curing-generated chromophores and result in non-discoloring of EVA. By using better performance stabilizers to minimize the curing-generated UV-excitable chromophores, a new fast curing agent, and no UV absorber, the NREL-developed EVA formulations show a superior photothermal stability against browning to the commercial counterparts. Alternatively, the discoloration rate of the commercial EVA pottants can be considerably reduced by using UV-filtering glass superstrates that largely inhibit the UV-induced photooxidation reactions, or completely eliminated by using air-permeable polymer superstrate films that enable photobleaching reactions. {copyright} {ital 1999 American Institute of Physics.}

Authors:
; ;  [1]
  1. Engineering and Reliability Division, National Center for Photovoltaics, National Renewable Energy Laboratory, 1617 Cole Blvd., Golden, Colorado 80401 (United States)
Publication Date:
Research Org.:
National Renewable Energy Laboratory
Sponsoring Org.:
USDOE
OSTI Identifier:
357202
Report Number(s):
CONF-980935-
Journal ID: APCPCS; ISSN 0094-243X; TRN: 9915M0088
DOE Contract Number:  
AC36-83CH10093
Resource Type:
Journal Article
Journal Name:
AIP Conference Proceedings
Additional Journal Information:
Journal Volume: 462; Journal Issue: 1; Conference: 15. National Center for Photovoltaics program review conference, Denver, CO (United States), 9-11 Sep 1998; Other Information: PBD: Mar 1999
Country of Publication:
United States
Language:
English
Subject:
14 SOLAR ENERGY; SOLAR CELL ARRAYS; SOLAR ABSORBERS; ENCAPSULATION; STABILITY; COLOR; FABRICATION; SPECTRAL RESPONSE; VISIBLE SPECTRA

Citation Formats

Pern, F J, Glick, S H, and Czanderna, A W. Review of the photothermal stability of EVA pottants: Effects of formulation on the discoloration rate and mitigation methods. United States: N. p., 1999. Web. doi:10.1063/1.58004.
Pern, F J, Glick, S H, & Czanderna, A W. Review of the photothermal stability of EVA pottants: Effects of formulation on the discoloration rate and mitigation methods. United States. doi:10.1063/1.58004.
Pern, F J, Glick, S H, and Czanderna, A W. Mon . "Review of the photothermal stability of EVA pottants: Effects of formulation on the discoloration rate and mitigation methods". United States. doi:10.1063/1.58004.
@article{osti_357202,
title = {Review of the photothermal stability of EVA pottants: Effects of formulation on the discoloration rate and mitigation methods},
author = {Pern, F J and Glick, S H and Czanderna, A W},
abstractNote = {Results from extensive studies of the commercial ethylene vinyl acetate (EVA) formulations show that the UV absorber and curing-generated UV-excitable, {alpha},{beta}-unsaturated carbonyl chromophores facilitate the EVA discoloration, which is further enhanced by curing-generated acetic acid and probably residual peroxide curing agent also. Formation and concentration of the UV-excitable chromophores are substantially promoted by the antioxidant, Naugard P. The discoloration rate is greater under higher UV light intensity and temperatures. Heating in the dark at elevated temperatures (e.g., 85&hthinsp;{degree}C) in the air for {approximately}200 days only results in light yellowing. The discoloration reactions compete with photobleaching reactions, which destroy curing-generated chromophores and result in non-discoloring of EVA. By using better performance stabilizers to minimize the curing-generated UV-excitable chromophores, a new fast curing agent, and no UV absorber, the NREL-developed EVA formulations show a superior photothermal stability against browning to the commercial counterparts. Alternatively, the discoloration rate of the commercial EVA pottants can be considerably reduced by using UV-filtering glass superstrates that largely inhibit the UV-induced photooxidation reactions, or completely eliminated by using air-permeable polymer superstrate films that enable photobleaching reactions. {copyright} {ital 1999 American Institute of Physics.}},
doi = {10.1063/1.58004},
journal = {AIP Conference Proceedings},
number = 1,
volume = 462,
place = {United States},
year = {1999},
month = {3}
}