{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,1,31]],"date-time":"2026-01-31T08:54:45Z","timestamp":1769849685654,"version":"3.49.0"},"reference-count":124,"publisher":"MDPI AG","issue":"14","license":[{"start":{"date-parts":[[2021,7,12]],"date-time":"2021-07-12T00:00:00Z","timestamp":1626048000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100001871","name":"Funda\u00e7\u00e3o para a Ci\u00eancia e a Tecnologia","doi-asserted-by":"publisher","award":["PD\/00253\/2012"],"award-info":[{"award-number":["PD\/00253\/2012"]}],"id":[{"id":"10.13039\/501100001871","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100001871","name":"Funda\u00e7\u00e3o para a Ci\u00eancia e a Tecnologia","doi-asserted-by":"publisher","award":["PB\/BD\/114412\/2016"],"award-info":[{"award-number":["PB\/BD\/114412\/2016"]}],"id":[{"id":"10.13039\/501100001871","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100001871","name":"Funda\u00e7\u00e3o para a Ci\u00eancia e a Tecnologia","doi-asserted-by":"publisher","award":["PTDC\/IVC-HFC\/5174\/2014"],"award-info":[{"award-number":["PTDC\/IVC-HFC\/5174\/2014"]}],"id":[{"id":"10.13039\/501100001871","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100001871","name":"Funda\u00e7\u00e3o para a Ci\u00eancia e a Tecnologia","doi-asserted-by":"publisher","award":["UIDB\/50006\/2020"],"award-info":[{"award-number":["UIDB\/50006\/2020"]}],"id":[{"id":"10.13039\/501100001871","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Polymers"],"abstract":"<jats:p>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\u2014EGA-MS, PY-GC\/MS, and TD-GC\/MS\u2014were successfully employed for characterizing the plastic formulations and degradation. The identification of phthalic compounds in both aged \u03b2-naphthol powders opens new venues for studies on their degradation. This work\u2019s approach and analytical methods in studying the discoloration of historical plastics are novel, proving their efficacy, reliability, and potentiality.<\/jats:p>","DOI":"10.3390\/polym13142278","type":"journal-article","created":{"date-parts":[[2021,7,12]],"date-time":"2021-07-12T21:56:37Z","timestamp":1626126997000},"page":"2278","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":17,"title":["Discoloration of Historical Plastic Objects: New Insight into the Degradation of \u03b2-Naphthol Pigment Lakes"],"prefix":"10.3390","volume":"13","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-1073-1723","authenticated-orcid":false,"given":"Anna","family":"Micheluz","sequence":"first","affiliation":[{"name":"Conservation Science Department, Deutsches Museum, Museumsinsel 1, 80538 Munich, Germany"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-9259-674X","authenticated-orcid":false,"given":"Eva Mariasole","family":"Angelin","sequence":"additional","affiliation":[{"name":"Department of Conservation and Restoration and LAQV-REQUIMTE, NOVA School of Science and Technology, NOVA University Lisbon, 2829-516 Lisbon, Portugal"}]},{"given":"Jo\u00e3o Almeida","family":"Lopes","sequence":"additional","affiliation":[{"name":"iMed.ULisboa-Research Institute for Medicines, Faculty of Pharmacy, University of Lisbon, Av. Prof. Gama Pinto, 1649-003 Lisbon, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-7393-6801","authenticated-orcid":false,"given":"Maria Jo\u00e3o","family":"Melo","sequence":"additional","affiliation":[{"name":"Department of Conservation and Restoration and LAQV-REQUIMTE, NOVA School of Science and Technology, NOVA University Lisbon, 2829-516 Lisbon, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-0262-3549","authenticated-orcid":false,"given":"Marisa","family":"Pamplona","sequence":"additional","affiliation":[{"name":"Conservation Science Department, Deutsches Museum, Museumsinsel 1, 80538 Munich, Germany"}]}],"member":"1968","published-online":{"date-parts":[[2021,7,12]]},"reference":[{"key":"ref_1","unstructured":"Quye, A., and Williamson, C. (1999). Plastics: Collecting and Conserving, NMS Publishing Ltd."},{"key":"ref_2","unstructured":"Cecchini, C., and Petroni, M. (2015). Plastic Days. 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