{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,27]],"date-time":"2026-09-27T14:57:34Z","timestamp":1790521054058,"version":"4.1.0"},"reference-count":27,"publisher":"SAGE Publications","license":[{"start":{"date-parts":[[2026,8,1]],"date-time":"2026-08-01T00:00:00Z","timestamp":1785542400000},"content-version":"tdm","delay-in-days":0,"URL":"https:\/\/journals.sagepub.com\/page\/policies\/text-and-data-mining-license"}],"funder":[{"name":"A*STAR IAF-ICP","award":["I2501E0051"],"award-info":[{"award-number":["I2501E0051"]}]},{"name":"A*STAR Aerospace Programme Cycle 17","award":["M2315a0080"],"award-info":[{"award-number":["M2315a0080"]}]}],"content-domain":{"domain":["journals.sagepub.com"],"crossmark-restriction":true},"short-container-title":["Appl Spectrosc"],"abstract":"<jats:p>\n                    This work utilized terahertz time-domain spectroscopy (THz-TDS) and Fourier Transform Infrared (FTIR) spectroscopy to characterize epoxy blends. The epoxy blends were prepared by blending a virgin DER-332\/LC-100 epoxy system with Recovered Epoxy Polymer (REP) at 1-10\u2005wt%, and were compared with references of virgin epoxy and REP. The REP was obtained via peracetic acid digestion of Carbon Fibre Reinforced Polymer (CFRP), followed by purification. Using THz-TDS amplitude-phase analysis, five optical parameters were obtained: refractive index (\n                    <jats:italic toggle=\"yes\">n)<\/jats:italic>\n                    , extinction coefficient (\n                    <jats:italic toggle=\"yes\">\u03ba)<\/jats:italic>\n                    , absorption coefficient (\u03b1), and the real and imaginary of the dielectric constant (\u03b5\u2032 and \u03b5\u2033). Under ambient conditions, these parameters extracted from THz-TDS were unable to distinguish low REP content 0\u201310% REP but were able to clearly differentiate 100% REP from all other epoxy blends. Compared to the other blends, 100% REP shows markedly increased\n                    <jats:italic toggle=\"yes\">n<\/jats:italic>\n                    ,\n                    <jats:italic toggle=\"yes\">\u03ba<\/jats:italic>\n                    ,\n                    <jats:italic toggle=\"yes\">\u03b1<\/jats:italic>\n                    , \u03b5\u2032, and \u03b5\u2033, attributed to oxidation, formation of polar groups, chain scission and microvoid-induced scattering. To distinguish low REP-content blends using THz-TDS, external perturbation was applied. Under perturbation, linear concentration-dependent trends in \u0394\n                    <jats:italic toggle=\"yes\">n<\/jats:italic>\n                    , \u0394\n                    <jats:italic toggle=\"yes\">\u03ba<\/jats:italic>\n                    , \u0394\u03b1, \u0394\u03b5\u2032 and \u0394\u03b5\u2032\u2032 were observed. The external perturbation enhanced the interaction between the samples and the THz wave, likely due to amplification of dipole relaxation. Additionally, the transmission spectra (3500-7500\u2005cm\n                    <jats:sup>\u22121<\/jats:sup>\n                    ) obtained from FTIR increased as the REP content increased from 0-10%. This concentration dependent trend can be attributed to partial network dilution and reduced overtone absorption. However, the transmission of 100% REP showed strong attenuation due to structural disorder and enhanced scattering.\n                  <\/jats:p>","DOI":"10.1177\/00037028261477156","type":"journal-article","created":{"date-parts":[[2026,8,1]],"date-time":"2026-08-01T09:35:18Z","timestamp":1785576918000},"update-policy":"https:\/\/doi.org\/10.1177\/sage-journals-update-policy","source":"Crossref","is-referenced-by-count":0,"title":["Percolation-Governed Transitions in Recycled Epoxy Composites: A Terahertz Spectroscopy Framework for Multiscale Degradation and Property Prediction"],"prefix":"10.1177","author":[{"ORCID":"https:\/\/orcid.org\/0009-0004-7625-2113","authenticated-orcid":false,"given":"Bryan Zhi Chuan","family":"Foong","sequence":"first","affiliation":[{"name":"Technology and Research (A*STAR)"},{"name":"School of Chemistry, Chemical Engineering and Biotechnology, Nanyang Technological University, Singapore, Singapore"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-2525-8334","authenticated-orcid":false,"given":"Qing Yang Steve","family":"Wu","sequence":"additional","affiliation":[{"name":"Technology and Research (A*STAR)"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Xiaobai","family":"Wang","sequence":"additional","affiliation":[{"name":"Technology and Research (A*STAR)"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0002-5234-6743","authenticated-orcid":false,"given":"Angeline Yan Xuan","family":"Tan","sequence":"additional","affiliation":[{"name":"Technology and Research (A*STAR)"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Ching Mui","family":"Cho","sequence":"additional","affiliation":[{"name":"Technology and Research (A*STAR)"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-8389-5396","authenticated-orcid":false,"given":"Siok Wei","family":"Tay","sequence":"additional","affiliation":[{"name":"Technology and Research (A*STAR)"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-3941-5003","authenticated-orcid":false,"given":"Jing","family":"Zhang","sequence":"additional","affiliation":[{"name":"Agency for Science, Technology and Research"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-2607-5129","authenticated-orcid":false,"given":"Lin","family":"Ke","sequence":"additional","affiliation":[{"name":"Technology and Research (A*STAR)"},{"name":"Singapore Institute of Technology"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"179","published-online":{"date-parts":[[2026,8,1]]},"reference":[{"key":"e_1_3_2_2_2","doi-asserted-by":"publisher","DOI":"10.1016\/j.compscitech.2022.109761"},{"key":"e_1_3_2_3_2","doi-asserted-by":"publisher","DOI":"10.1146\/annurev-chembioeng-120919-012253"},{"key":"e_1_3_2_4_2","doi-asserted-by":"publisher","DOI":"10.1016\/j.compositesb.2020.108053"},{"key":"e_1_3_2_5_2","doi-asserted-by":"publisher","DOI":"10.1039\/D2GC00368F"},{"key":"e_1_3_2_6_2","doi-asserted-by":"publisher","DOI":"10.3390\/ma14216401"},{"key":"e_1_3_2_7_2","doi-asserted-by":"publisher","DOI":"10.3390\/jcs8010002"},{"key":"e_1_3_2_8_2","volume-title":"Spectrometric identification of organic compounds","author":"Silverstein RM","year":"2005","unstructured":"Silverstein RM, Webster FX, Kiemle DJ. 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Purdue University; 2021. https:\/\/docs.lib.purdue.edu\/dissertations\/AAI30504804"},{"key":"e_1_3_2_28_2","doi-asserted-by":"publisher","DOI":"10.3390\/ma15238468"}],"container-title":["Applied Spectroscopy"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/journals.sagepub.com\/doi\/pdf\/10.1177\/00037028261477156","content-type":"application\/pdf","content-version":"vor","intended-application":"text-mining"},{"URL":"https:\/\/journals.sagepub.com\/doi\/full-xml\/10.1177\/00037028261477156","content-type":"application\/xml","content-version":"vor","intended-application":"text-mining"},{"URL":"https:\/\/journals.sagepub.com\/doi\/pdf\/10.1177\/00037028261477156","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,9,27]],"date-time":"2026-09-27T14:33:13Z","timestamp":1790519593000},"score":1,"resource":{"primary":{"URL":"https:\/\/journals.sagepub.com\/doi\/10.1177\/00037028261477156"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,8,1]]},"references-count":27,"alternative-id":["10.1177\/00037028261477156"],"URL":"https:\/\/doi.org\/10.1177\/00037028261477156","relation":{},"ISSN":["0003-7028","1943-3530"],"issn-type":[{"value":"0003-7028","type":"print"},{"value":"1943-3530","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,8,1]]},"article-number":"00037028261477156"}}