Experimental study on bio-based fire retardant: Lignin coating for sustainable wood protection

Thumbnail Image

Files

master_Liu_Mi_2025.pdf (1.7 MB)

URL

Journal Title

Journal ISSN

Volume Title

School of Engineering | Master's thesis
Unless otherwise stated, all rights belong to the author. You may download, display and print this publication for Your own personal use. Commercial use is prohibited.

Authors

Date

2025-11-17

Department

Major/Subject

Building Technology

Mcode

Degree programme

Master's Programme in Building Technology
Rakennustekniikan maisteriohjelma
Magisterprogrammet i byggnadsteknik

Language

en

Pages

53

Series

Abstract

This study investigates the fire-retardant performance and underlying mechanisms of a novel bio-based lignin coating and its composite formulation on spruce wood (Picea abies). A commercial fire-retardant benchmark (C1) and a lignin-based composite (C3) were analysed via Thermogravimetric Analysis (TGA) and Cone Calorimetry (50 kW/m2) to evaluate thermal stability, heat release, and production of toxic compounds. The experimental results establish the lignin coating’s primary role as a robust condensed phase fire retardant. The coating promotes substantial char residue formation, as demonstrated by TGA curves which showed a broader decomposition range for treated samples compared to untreated wood. The Lignin + Additives composite (C3) retained up to 44% more mass than the untreated wood in TGA tests. This performance provided a significant thermal barrier and offered evidence of a distinct delay in the second Heat Release Rate (HRR) peak. The performance profiles confirmed the necessity of multi-phase synergy. The Commercial (C1) sample achieved the most effective HRR suppression, which is indicative of gas phase inhibition due to its lowest Effective Heat of Combustion EHC profile. The most significant finding was the synergistic action in the C3 composite, which successfully combined the insulating charforming capability of the lignin with the flame suppression provided by the additive (monomagnesiumphosphate). This system achieved a comprehensive balance of hazard reduction. The analysis of combustion byproducts also verified a critical safety trade-off: the highly suppressive C1 coating was linked to elevated sustained smoke yield, whereas the C3 composite demonstrated a better overall safety balance between HRR reduction and toxic product evolution. The study establishes lignin as a potential component for developing effective, sustainable fire-retardant systems.

Description

Supervisor

Hostikka, Simo

Keywords

lignin, fire retardant (FR), cone calorimeter, TGA, pyrolysis, fire testing

Other note

Citation

Permanent link to this item

https://urn.fi/URN:NBN:fi:aalto-202512159153

Collections

[dipl] Insinööritieteiden korkeakoulu / ENG