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Mechanism and kinetics of thermal degradation of insulating materials developed from cellulose fiber and fire retardants
KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.ORCID iD: 0000-0002-2272-5067
KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.ORCID iD: 0000-0002-7055-1057
KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.ORCID iD: 0000-0003-3858-8324
2019 (English)In: Journal of thermal analysis and calorimetry (Print), ISSN 1388-6150, E-ISSN 1588-2926, Vol. 135, no 6, p. 3015-3027Article in journal (Refereed) Published
Abstract [en]

The mechanism and kinetics of thermal degradation of materials developed from cellulose fiber and synergetic fire retardant or expandable graphite have been investigated using thermogravimetric analysis. The model-free methods such as Kissinger–Akahira–Sunose (KAS), Friedman, and Flynn–Wall–Ozawa (FWO) were applied to measure apparent activation energy (Ea).The increased Ea indicated a greater thermal stability because of the formation of a thermally stable char, and the decreased Ea after the increasing region related to the catalytic reaction of the fire retardants, which revealed that the pyrolysis of fire retardant-containing cellulosic materials through more complex and multi-step kinetics. The Friedman method can be considered as the best method to evaluate the Ea of fire-retarded cellulose thermal insulation compared with the KAS and two methods. A master-plots method such as the Criado method was used to determine the possible degradation mechanisms. The degradation of cellulose thermal insulation without a fire retardant is governed by a D3 diffusion process when the conversion value is below 0.6, but the materials containing synergetic fire retardant and expandable graphite fire retardant may have a complicated reaction mechanism that fits several proposed theoretical models in different conversion ranges. Gases released during the thermal degradation were identified by pyrolysis–gas chromatography/mass spectrometry. Fire retardants could catalyze the dehydration of cellulosic thermal insulating materials at a lower temperature and facilitate the generation of furfural and levoglucosenone, thus promoting the formation of char. These results provide useful information to understand the pyrolysis and fire retardancy mechanism of fire-retarded cellulose thermal insulation.

Place, publisher, year, edition, pages
Springer Netherlands, 2019. Vol. 135, no 6, p. 3015-3027
Keywords [en]
Thermal degradation, Thermal kinetics, Fire retardant, Cellulose fiber, Thermal insulating
National Category
Paper, Pulp and Fiber Technology Wood Science
Identifiers
URN: urn:nbn:se:kth:diva-233485DOI: 10.1007/s10973-018-7564-5ISI: 000462553400011Scopus ID: 2-s2.0-85050669625OAI: oai:DiVA.org:kth-233485DiVA, id: diva2:1240255
Funder
Swedish Research Council Formas
Note

QC 20180821

Available from: 2018-08-20 Created: 2018-08-20 Last updated: 2019-08-27Bibliographically approved
In thesis
1. Cellulosic Thermal Insulation with Improved Water Resistance and Fire Retardancy
Open this publication in new window or tab >>Cellulosic Thermal Insulation with Improved Water Resistance and Fire Retardancy
2018 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Sweden is one of the largest countries by area in Europe, and almost 70% of it is covered by forest. These abundant forest resources benefit the Swedish bioeconomy, but the pulp and paper industry is facing the challenge of a decrease in the demand for printing paper due to a significant shift to electronic media; therefore, it is a priority to use pulp to produce alternative value-added products, such as thermal insulating materials in buildings. Cellulosic thermal insulation can reduce the heating energy consumption of buildings, and decrease the emission of CO2, thus contributing to a sustainable society.

However, cellulosic thermal insulation needs to overcome its poor water resistance, to lower the risk of fungi and ensure a good interior air quality. In the work described in this thesis, cellulosic insulation materials have been produced from pulp fibers, water, and foaming agent by a foam-forming technique. Hydrophobic extractives isolated from birch outer bark were used to functionalize the insulating materials. These materials showed an improved water resistance due to the intrinsic non-polarity of the extractives, promising thermal insulation properties and fungal resistance.

Fire retardancy is another challenge for cellulosic thermal insulation, and cellulosic insulation materials were here prepared from formulations containing pulp and commercial fire retardants. Fire test results showed that the materials containing 20% expandable graphite or 25% synergetic fire retardant had a significantly improved fire retardancy, being able to resist a small flame attack for a short period without substantial flame spreading. A study of the mechanism of fire retardancy confirmed that the fire retardants can catalyze the dehydration of pulp and promote the generation of a protective char layer that prevents the materials from further decomposition.

Bio-based fire-retardant coatings such as sulfonated kraft lignin and nanoclay can provide a more efficient fire-retardant protection on the cellulosic insulation than a fire retardant incorporated in the materials. A nanoclay coating performed the best because of its very good thermal stability. The effective bio-based fire-retardant coating is promising for future use in cellulosic thermal insulation materials.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2018. p. 59
Series
TRITA-CBH-FOU ; 2018:29
Keywords
Bio-based, Cellulosic, Fire retardant, Thermal insulation
National Category
Paper, Pulp and Fiber Technology Wood Science
Research subject
Fibre and Polymer Science
Identifiers
urn:nbn:se:kth:diva-233516 (URN)978-91-7729-864-9 (ISBN)
Public defence
2018-09-14, K1, Teknikringen 56, KTH Campus, Stockholm, 10:00 (English)
Opponent
Supervisors
Projects
Energy-efficient cellulosic insulation products/panels for green building solutions
Funder
Swedish Research Council Formas
Note

QC 20180821

Available from: 2018-08-21 Created: 2018-08-21 Last updated: 2018-08-21Bibliographically approved

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Zheng, ChaoLi, DongfangEk, Monica

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