{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,2]],"date-time":"2026-08-02T04:47:20Z","timestamp":1785646040915,"version":"3.56.0"},"reference-count":36,"publisher":"MDPI AG","issue":"15","license":[{"start":{"date-parts":[[2026,7,31]],"date-time":"2026-07-31T00:00:00Z","timestamp":1785456000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100001809","name":"National Natural Science Foundation of China","doi-asserted-by":"crossref","award":["32301524"],"award-info":[{"award-number":["32301524"]}],"id":[{"id":"10.13039\/501100001809","id-type":"DOI","asserted-by":"crossref"}]},{"DOI":"10.13039\/501100001809","name":"National Natural Science Foundation of China","doi-asserted-by":"crossref","award":["32271788"],"award-info":[{"award-number":["32271788"]}],"id":[{"id":"10.13039\/501100001809","id-type":"DOI","asserted-by":"crossref"}]},{"award":["32301524"],"award-info":[{"award-number":["32301524"]}],"id":[{"id":"https:\/\/ror.org\/01h0zpd94","id-type":"ROR","asserted-by":"publisher"}]},{"award":["32271788"],"award-info":[{"award-number":["32271788"]}],"id":[{"id":"https:\/\/ror.org\/01h0zpd94","id-type":"ROR","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100005632","name":"National Key Research and Development Program of China","doi-asserted-by":"publisher","award":["2022YFD2200702"],"award-info":[{"award-number":["2022YFD2200702"]}],"id":[{"id":"10.13039\/501100005632","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Polymers"],"abstract":"<jats:p>Vinyl acetate\u2013ethylene copolymer emulsion (VAE) adhesives are widely used in formaldehyde-free wood-based panels and coating systems, but their inherent flammability limits broader application in fire-safety-demanding fields. In this work, fly ash (FA), an industrial solid waste rich in Si- and Al-containing inorganic components, was introduced into a conventional ammonium polyphosphate\/melamine\/pentaerythritol (APP\/MEL\/PER) intumescent flame-retardant (IFR) system to prepare flame-retardant VAE emulsion adhesives. The results showed that the incorporation of IFR effectively improved the flame retardancy of VAE, while FA further enhanced the condensed-phase protective effect. The limiting oxygen index (LOI) of VAE\/IFR\/FA increased to 28.5% from 18.3% for neat VAE, and the sample achieved a UL-94 V-0 rating. Cone calorimetry results showed that the peak heat release rate and total heat release were significantly reduced after flame-retardant modification, accompanied by an increase in residual char. The VAE\/IFR\/FA sample exhibited the highest char residue and the lowest total smoke production, indicating the positive role of FA in promoting char formation and smoke suppression. The addition of KH403 further regulated the combustion behavior, mainly improving early-stage heat release suppression and fire performance index rather than increasing the final char yield. The KH403-containing formulation also showed improved tensile properties and plywood bonding strength, indicating its potential as a flame-retardant adhesive for wood-based panels. The KH403-containing formulation also showed improved tensile properties and plywood bonding strength, indicating its potential as a flame-retardant adhesive for wood-based panels. SEM-EDS, XPS, Raman, and TG-FTIR analyses confirmed that FA and KH403 contributed to the formation of a phosphorus-rich organic\u2013inorganic hybrid char layer containing Si\/Al inorganic structures. This reinforced char layer effectively inhibited heat transfer, oxygen diffusion, and the release of combustible volatiles. This study provides a feasible strategy for developing low-cost flame-retardant VAE adhesives while promoting the high-value utilization of fly ash.<\/jats:p>","DOI":"10.3390\/polym18151884","type":"journal-article","created":{"date-parts":[[2026,7,31]],"date-time":"2026-07-31T10:11:38Z","timestamp":1785492698000},"page":"1884","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Flame Retardancy of Vinyl Acetate\u2013Ethylene Emulsion Adhesives Modified with Intumescent Flame Retardants and Fly Ash"],"prefix":"10.3390","volume":"18","author":[{"given":"Qianqian","family":"Wang","sequence":"first","affiliation":[{"name":"National Key Laboratory of Strength and Structural Integrity, School of Aeronautic Science and Engineering, Beihang University, Beijing 100191, China"},{"name":"Shandong Institute of Nonmetallic Materials, Jinan 250031, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jing","family":"Luo","sequence":"additional","affiliation":[{"name":"China Nuclear Power Engineering Co., Ltd., Beijing 100840, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yan","family":"Sun","sequence":"additional","affiliation":[{"name":"Shandong Institute of Nonmetallic Materials, Jinan 250031, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Wei","family":"Liu","sequence":"additional","affiliation":[{"name":"Sichuan Fire Research Institute of Ministry of Emergency Management, Chengdu 610036, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Xucai","family":"Wang","sequence":"additional","affiliation":[{"name":"Shandong Institute of Nonmetallic Materials, Jinan 250031, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-5076-0943","authenticated-orcid":false,"given":"Peng","family":"Jiang","sequence":"additional","affiliation":[{"name":"Research Institute of Wood Industry, Chinese Academy of Forestry, Beijing 100091, China"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2026,7,31]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"118170","DOI":"10.1016\/j.ces.2022.118170","article-title":"Simulation study on the co-polymerization of vinyl acetate between ethylene","volume":"264","author":"Dong","year":"2022","journal-title":"Chem. 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