Complementary techniques of thermal analysis as a tool for studying the properties and effectiveness of intumescent coatings deposited on wood

Čelan Korošin, Nataša (author), Cerc Korošec, Romana (author)

Fire-retardant intumescent coatings offer an effective means of enhancing the fire resistance of combustible substrates such as wood. These coatings have a complex chemical composition and, when exposed to temperatures above 200 °C, undergo an intumescent reaction accompanied by the release of non-flammable gases, forming an expanded, charred layer with low thermal conductivity. This provides thermal insulation and acts as a physical barrier against heat, oxygen, and flammable volatiles. In this study, the applicability of several thermoanalytical techniques for evaluating the performance of three different intumescent coatings applied to spruce wood was investigated. Simultaneous thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) showed that coating No. 3 was the most efficient, initiating substrate protection at the lowest temperature and reducing the combustion enthalpy by approximately 50% compared to uncoated wood. DSC-microscopy visualization enabled direct observation of the intumescent expansion, degradation of the carbonized protective layer, and delayed thermal decomposition of coated wood. Furthermore, a comparison between TGA-MS and TGA-IST16-GC-MS demonstrated the superiority of chromatographic separation for identifying evolved gaseous products. While TGA-MS is effective for detecting small gaseous species (e.g., H$_2$O, CO$_2$, formaldehyde), TGA-IST16-GC-MS enables the deconvolution of many degradation products evolving simultaneously, allowing for distinction between flame-retardant-related species, polymer backbone fragments, nitrogen-rich heterocycles, and small oxygenated molecules in the most effective coating.

• Language: English
• Keywords: thermal stability, flammability, flame retardancy, intumescence coatings, wood protection, TGA-MS, TGA-IST16-GC-MS, DSC-microscopy
• Work type: Article
• Typology: 1.01 - Original Scientific Article
• Organization: FKKT - Faculty of Chemistry and Chemical Technology
• Publication status: Published
• Publication version: Version of Record
• Year: 2026
• Number of pages: 14 str.
• Numbering: Vol. 18, iss. 2, art. 202
• PID: 20.500.12556/RUL-178464
• UDC: 543.57
• ISSN on article: 2073-4360
• DOI: 10.3390/polym18020202
• COBISS.SI-ID: 264373251
• Publication date in RUL: 28.01.2026

Record is a part of a journal

• Title: Polymers
• Shortened title: Polymers
• Publisher: MDPI
• ISSN: 2073-4360
• COBISS.SI-ID: 517951257

Licences

• License: CC BY 4.0, Creative Commons Attribution 4.0 International
• Link: http://creativecommons.org/licenses/by/4.0/
• Description: This is the standard Creative Commons license that gives others maximum freedom to do what they want with the work as long as they credit the author.

Secondary language

• Language: Slovenian
• Keywords: toplotna stabilnost, vnetljivost, zaviranje gorenja, intumescenčni premazi, zaščita lesa, TGA-MS, TGA-IST16-GC-MS, DSC mikroskopija

Projects

• Funder: ARIS - Slovenian Research and Innovation Agency
• Project number: P1-0134-2022
• Name: Kemija za trajnostni razvoj

• Funder: ARIS - Slovenian Research and Innovation Agency
• Project number: I0-0022-2022
• Name: Mreža raziskovalnih infrastrukturnih centrov Univerze v Ljubljani (MRIC UL)