TY - JOUR
T1 - Discoloration of historical plastic objects
T2 - New insight into the degradation of β-naphthol pigment lakes
AU - Micheluz, Anna
AU - Angelin, Eva Mariasole
AU - Lopes, João Almeida
AU - Melo, Maria João
AU - Pamplona, Marisa
N1 - Funding Information:
info:eu-repo/grantAgreement/FCT/6817 - DCRRNI ID/UIDB%2F50006%2F2020/PT#
info:eu-repo/grantAgreement/FCT/3599-PPCDT/PTDC%2FIVC-HFC%2F5174%2F2014/PT#
This research was funded by Fundação para a Ciência e a Tecnologia, Ministério da Ciência Tecnologia e Ensino Superior (FCT/MCTES), Portugal, through doctoral programme CORES-PD/00253/2012, PB/BD/114412/2016.
info:eu-repo/grantAgreement/FCT/6817 - DCRRNI ID/UIDB%2F50006%2F2020/PT#
info:eu-repo/grantAgreement/FCT/3599-PPCDT/PTDC%2FIVC-HFC%2F5174%2F2014/PT#
Funding Information:
This research was funded by Funda??o para a Ci?ncia e a Tecnologia, Minist?rio da Ci?ncia Tecnologia e Ensino Superior (FCT/MCTES), Portugal, through doctoral programme CORESPD/00253/2012, PB/BD/114412/2016 doctoral grant. Associate Laboratory for Green Chemistry? LAQV,(PTDC/IVC-HFC/5174/2014).
Publisher Copyright:
© 2021 by the authors. Licensee MDPI, Basel, Switzerland.
PY - 2021/7/12
Y1 - 2021/7/12
N2 - Light is a determining factor in the discoloration of plastics, and photodegradation processes can affect the molecular structures of both the polymer and colorants. Limited studies focused on the discoloration of heritage plastics in conservation science. This work investigated the discoloration of red historical polyethylene (PE) objects colored with PR 48:2 and PR 53:1. High-density and low-density PE reference polymers, neat pigment powders, and historical samples were assessed before and after accelerated photoaging. The applied methodology provided insight into the individual light-susceptibility of polyethylenes, organic pigment lakes, and their combined effect in the photoaging of historical plastic formulations. After light exposure, both PE references and historical samples yellowed, PR53:1 faded, and PR 48:2 darkened; however, both organic pigments faded severely in the historical samples. This highlights the role played by the plastic binder likely facilitating the pigment photofading. Fourier transform infrared spectroscopy and mass spectrometry techniques—EGA-MS, PY-GC/MS, and TD-GC/MS—were successfully employed for characterizing the plastic formulations and degradation. The identification of phthalic compounds in both aged β-naphthol powders opens new venues for studies on their degradation. This work’s approach and analytical methods in studying the discoloration of historical plastics are novel, proving their efficacy, reliability, and potentiality.
AB - Light is a determining factor in the discoloration of plastics, and photodegradation processes can affect the molecular structures of both the polymer and colorants. Limited studies focused on the discoloration of heritage plastics in conservation science. This work investigated the discoloration of red historical polyethylene (PE) objects colored with PR 48:2 and PR 53:1. High-density and low-density PE reference polymers, neat pigment powders, and historical samples were assessed before and after accelerated photoaging. The applied methodology provided insight into the individual light-susceptibility of polyethylenes, organic pigment lakes, and their combined effect in the photoaging of historical plastic formulations. After light exposure, both PE references and historical samples yellowed, PR53:1 faded, and PR 48:2 darkened; however, both organic pigments faded severely in the historical samples. This highlights the role played by the plastic binder likely facilitating the pigment photofading. Fourier transform infrared spectroscopy and mass spectrometry techniques—EGA-MS, PY-GC/MS, and TD-GC/MS—were successfully employed for characterizing the plastic formulations and degradation. The identification of phthalic compounds in both aged β-naphthol powders opens new venues for studies on their degradation. This work’s approach and analytical methods in studying the discoloration of historical plastics are novel, proving their efficacy, reliability, and potentiality.
KW - ATR-FTIR
KW - Colorant degradation
KW - Discoloration
KW - EGA-MS
KW - Fading
KW - Historical plastic objects
KW - Photodegradation
KW - Py-GC/MS
KW - TD-GC/MS
KW - β-naphthol pigment lakes
UR - http://www.scopus.com/inward/record.url?scp=85110836298&partnerID=8YFLogxK
U2 - 10.3390/polym13142278
DO - 10.3390/polym13142278
M3 - Article
C2 - 34301037
AN - SCOPUS:85110836298
VL - 13
JO - Polymers
JF - Polymers
IS - 14
M1 - 2278
ER -