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Dominguez, A., Borggren, J., Xu, C., Otxoterena, P., Försth, M., Leffler, T. & Bood, J. (2023). A compact Scheimpflug lidar imaging instrument for industrial diagnostics of flames. Measurement science and technology, 34(7), Article ID 075901.
Open this publication in new window or tab >>A compact Scheimpflug lidar imaging instrument for industrial diagnostics of flames
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2023 (English)In: Measurement science and technology, ISSN 0957-0233, E-ISSN 1361-6501, Vol. 34, no 7, article id 075901Article in journal (Refereed) Published
Abstract [en]

Scheimpflug lidar is a compact alternative to traditional lidar setups. With Scheimpflug lidar it is possible to make continuous range-resolved measurements. In this study we investigate the feasibility of a Scheimpflug lidar instrument for remote sensing in pool flames, which are characterized by strong particle scattering, large temperature gradients, and substantial fluctuations in particle distribution due to turbulence. An extinction coefficient can be extracted using the information about the transmitted laser power and the spatial extent of the flame. The transmitted laser power is manifested by the intensity of the 'echo' from a hard-target termination of the beam located behind the flame, while the information of the spatial extent of the flame along the laser beam is provided by the range-resolved scattering signal. Measurements were performed in heptane and diesel flames, respectively.

Place, publisher, year, edition, pages
Institute of Physics (IOP), 2023
Keywords
lidar, real-time monitoring, combustion
National Category
Atom and Molecular Physics and Optics
Research subject
Structural Engineering
Identifiers
urn:nbn:se:ltu:diva-96498 (URN)10.1088/1361-6501/acc268 (DOI)2-s2.0-85151560787 (Scopus ID)
Funder
Swedish Foundation for Strategic Research, TM17-0309Vinnova, 2018-01551
Note

Validerad;2023;Nivå 2;2023-04-14 (hanlid);

Available from: 2023-04-14 Created: 2023-04-14 Last updated: 2023-04-14Bibliographically approved
El Houssami, M., Försth, M., Fredriksson, H., Drean, V., Guillaume, E., Hofmann-Böllinghaus, A. & Sandinge, A. (2023). Fire safety of interior materials of buses. Fire and Materials, 47(7), 910-924
Open this publication in new window or tab >>Fire safety of interior materials of buses
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2023 (English)In: Fire and Materials, ISSN 0308-0501, E-ISSN 1099-1018, Vol. 47, no 7, p. 910-924Article in journal (Refereed) Published
Abstract [en]

This study provides an analysis on the fire safety of passengers and the fire protection of coaches and buses. A brief review of major bus fire incidents, an overview of current regulations in Europe, and their limitations are presented. The study finds that the current small-scale fire test methods described in UN ECE Reg No. 118 need to be replaced by test methods that can assess the reaction to fire of materials when exposed to ignition sources of varying sizes. To address these shortcomings, the study proposed an expert recommendation to update the material fire safety requirements and testing for buses. Additional measures are proposed, derived from objectives and strategies applied in other transport sectors, and can be tested through existing European and international standards, which are widely used by several industries. These measures aim to extend the time with tenable conditions for a safe evacuation in case of fire, reduce the degree of damage to buses, reduce the risk for fast and excessive thermal exposure on modern energy carriers needed for a more sustainable transport sector.

Place, publisher, year, edition, pages
John Wiley and Sons Ltd, 2023
Keywords
bus, coach, fire safety, interior materials, regulation, testing methods
National Category
Other Civil Engineering Building Technologies
Research subject
Structural Engineering
Identifiers
urn:nbn:se:ltu:diva-95856 (URN)10.1002/fam.3134 (DOI)000936975600001 ()2-s2.0-85149227479 (Scopus ID)
Note

Validerad;2023;Nivå 2;2023-11-01 (joosat);

Licens fulltext: CC BY-NC-ND License

Available from: 2023-03-13 Created: 2023-03-13 Last updated: 2023-11-01Bibliographically approved
Das, O., Mensah, R. A., Balasubramanian, K. B., Shanmugam, V., Försth, M., Hedenqvist, M. S., . . . Misra, M. (2023). Functionalised biochar in biocomposites: The effect of fire retardants, bioplastics and processing methods. Composites Part C: Open Access, 11, Article ID 100368.
Open this publication in new window or tab >>Functionalised biochar in biocomposites: The effect of fire retardants, bioplastics and processing methods
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2023 (English)In: Composites Part C: Open Access, E-ISSN 2666-6820, Vol. 11, article id 100368Article in journal (Refereed) Published
Abstract [en]

Fire retardants, although can impart fire-safety in polymeric composites, are detrimental to the mechanical properties. Biochar can be used, in conjunction with fire retardants, to create a balance between fire-safety and mechanical performance. It is possible to thermally dope fire retardants into the pores of biochar to make it functionalised. Thus, the current work is intended in identifying a composite having the combination of the most desirable fire retardant, bioplastic, and a suitable processing method. A comparison was made between two fire retardants (lanosol and ammonium polyphosphate), bioplastics (wheat gluten and polyamide 11), and composite processing methods (compression and injection moulding). It was found that wheat gluten containing ammonium polyphosphate-doped biochar made by compression moulding had the best fire-safety properties with the lowest peak heat release rate (186 kW/m2), the highest fire performance index (0.6 m2s/kW), and the lowest fire growth index (1.6 kW/ms) with acceptable mechanical properties compared to the corresponding neat bioplastic. Thus, for gluten-based polymers, the use of ammonium polyphosphate thermally doped into biochar processed by compression moulding is recommended to both simultaneously improve fire-safety and conserve the mechanical strength of the resulting biocomposites.

Place, publisher, year, edition, pages
Elsevier, 2023
Keywords
Biochar, Bioplastics, Compression moulding, Fire retardants, Injection moulding
National Category
Materials Chemistry Paper, Pulp and Fiber Technology
Research subject
Structural Engineering; Wood Science and Engineering
Identifiers
urn:nbn:se:ltu:diva-98229 (URN)10.1016/j.jcomc.2023.100368 (DOI)2-s2.0-85160716623 (Scopus ID)
Funder
Brandforsk, 321–002
Note

Validerad;2023;Nivå 2;2023-06-13 (hanlid)

Available from: 2023-06-13 Created: 2023-06-13 Last updated: 2023-09-05Bibliographically approved
Lin, C.-F., Karlsson, O., Das, O., Mensah, R. A., Mantanis, G. I., Jones, D., . . . Sandberg, D. (2023). High Leach-Resistant Fire-Retardant Modified Pine Wood (Pinus sylvestris L.) by In Situ Phosphorylation and Carbamylation. ACS Omega, 8(12), 11381-11396
Open this publication in new window or tab >>High Leach-Resistant Fire-Retardant Modified Pine Wood (Pinus sylvestris L.) by In Situ Phosphorylation and Carbamylation
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2023 (English)In: ACS Omega, E-ISSN 2470-1343, Vol. 8, no 12, p. 11381-11396Article in journal (Refereed) Published
Abstract [en]

The exterior application of fire-retardant (FR) timber necessitates it to have high durability because of the possibility to be exposed to rainfall. In this study, water-leaching resistance of FR wood has been imparted by grafting phosphate and carbamate groups of the water-soluble FR additives ammonium dihydrogen phosphate (ADP)/urea onto the hydroxyl groups of wood polymers via vacuum-pressure impregnation, followed by drying/heating in hot air. A darker and more reddish wood surface was observed after the modification. Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, solid-state 13C cross-polarization magic-angle-spinning nuclear magnetic resonance (13C CP-MAS NMR), and direct-excitation 31P MAS NMR suggested the formation of C–O–P covalent bonds and urethane chemical bridges. Scanning electron microscopy/energy-dispersive X-ray spectrometry suggested the diffusion of ADP/urea into the cell wall. The gas evolution analyzed by thermogravimetric analysis coupled with quadrupole mass spectrometry revealed a potential grafting reaction mechanism starting with the thermal decomposition of urea. Thermal behavior showed that the FR-modified wood lowered the main decomposition temperature and promoted the formation of char residues at elevated temperatures. The FR activity was preserved even after an extensive water-leaching test, confirmed by the limiting oxygen index (LOI) and cone calorimetry. The reduction of fire hazards was achieved through the increase of the LOI to above 80%, reduction of 30% of the peak heat release rate (pHRR2), reduction of smoke production, and a longer ignition time. The modulus of elasticity of FR-modified wood increased by 40% without significantly decreasing the modulus of rupture.

Place, publisher, year, edition, pages
American Chemical Society (ACS), 2023
National Category
Wood Science Physical Chemistry
Research subject
Wood Science and Engineering; Structural Engineering; Chemistry of Interfaces
Identifiers
urn:nbn:se:ltu:diva-95881 (URN)10.1021/acsomega.3c00146 (DOI)000960080200001 ()37008136 (PubMedID)2-s2.0-85150425157 (Scopus ID)
Funder
Swedish Research Council Formas, 2021-00818
Note

Validerad;2023;Nivå 2;2023-04-21 (joosat);

Funder: OP RDE (Grant no.CZ.02.1.01/0.0/0.0/16_019/0000803); CT WOOD, Luleå University of Technology

Licens fulltext: CC BY License

Available from: 2023-03-15 Created: 2023-03-15 Last updated: 2023-09-22Bibliographically approved
Wen, R., Tu, Y., Guo, T., Yu, Q., Shi, P., Ji, Y., . . . Elfgren, L. (2023). Molecular dynamics study on coupled ion transport in aluminium-doped cement-based materials: Effect of concentration. Advances in Cement Research, 35(2), 81-95
Open this publication in new window or tab >>Molecular dynamics study on coupled ion transport in aluminium-doped cement-based materials: Effect of concentration
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2023 (English)In: Advances in Cement Research, ISSN 0951-7197, E-ISSN 1751-7605, Vol. 35, no 2, p. 81-95Article in journal (Refereed) Published
Abstract [en]

The mutual inhibition effect of transport of sulphate and chloride in concrete specimen was determined in a macroscopic experiment. Higher concentration of sulphate has a better inhibition effect on chloride transport and the opposite is also true. In this paper, molecular dynamics (MD) simulation was performed to explore the effect of concentration (0, 0.5, 1.0 mol/L) on the transport of mixed solutions (NaCl and Na2SO4) in the main hydration products of aluminium-doped cement-based materials (i.e., calcium-aluminium-silicate-hydrate (C-A-S-H) gel). Sulphate was found to promote the aggregation of other ions to form ion clusters, which can reduce the effective width of the channel entrance and create a “necking” effect, thus reducing the overall transport rate of the solution. With the increase of NaCl concentration, sulphate ions in the mixed solution can adsorb more Na+ and Cl+ ions, and then form larger ion clusters to block the nanopores. Moreover, with increasing Na2SO4 concentration, higher amount of sulphate ions existing in the solution makes it possible to form more ion clusters. The results can provide a reasonable nanoscale explanation for macroscopic experiment.

Place, publisher, year, edition, pages
ICE Publishing, 2023
Keywords
Aluminates, Cement/cementitious materials, Durability, Nanostructure
National Category
Materials Chemistry
Research subject
Structural Engineering
Identifiers
urn:nbn:se:ltu:diva-92078 (URN)10.1680/jadcr.22.00028 (DOI)000836589300001 ()2-s2.0-85133177490 (Scopus ID)
Note

Validerad;2023;Nivå 2;2023-04-18 (joosat);

Available from: 2022-07-06 Created: 2022-07-06 Last updated: 2023-04-18Bibliographically approved
Kundu, C. K., Li, Z., Khan, M. A., Försth, M. & Das, O. (2023). Polypyrrole-modified multi-functional coatings for improved electro-conductive, hydrophilic and flame-retardant properties of polyamide 66 textiles. JCT Research, 20(4), 1223-1234
Open this publication in new window or tab >>Polypyrrole-modified multi-functional coatings for improved electro-conductive, hydrophilic and flame-retardant properties of polyamide 66 textiles
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2023 (English)In: JCT Research, ISSN 1547-0091, E-ISSN 2168-8028, Vol. 20, no 4, p. 1223-1234Article in journal (Refereed) Published
Place, publisher, year, edition, pages
Springer Nature, 2023
National Category
Textile, Rubber and Polymeric Materials
Research subject
Structural Engineering
Identifiers
urn:nbn:se:ltu:diva-95604 (URN)10.1007/s11998-022-00738-3 (DOI)000926114300001 ()2-s2.0-85147350892 (Scopus ID)
Note

Validerad;2023;Nivå 2;2023-08-15 (hanlid)

Available from: 2023-02-13 Created: 2023-02-13 Last updated: 2023-08-15Bibliographically approved
Sanned, E., Mensah, R. A., Försth, M. & Das, O. (2023). Response to the comments made by Vytenis Babrauskas on “the curious case of the second/end peak in the heat release rate of wood: A cone calorimeter investigation” [Letter to the editor]. Fire and Materials, 47(5), 735-735
Open this publication in new window or tab >>Response to the comments made by Vytenis Babrauskas on “the curious case of the second/end peak in the heat release rate of wood: A cone calorimeter investigation”
2023 (English)In: Fire and Materials, ISSN 0308-0501, E-ISSN 1099-1018, Vol. 47, no 5, p. 735-735Article in journal, Letter (Other academic) Published
Place, publisher, year, edition, pages
John Wiley and Sons Ltd, 2023
National Category
Other Civil Engineering
Research subject
Structural Engineering
Identifiers
urn:nbn:se:ltu:diva-100642 (URN)10.1002/fam.3149 (DOI)001041016500010 ()2-s2.0-85166416189 (Scopus ID)
Note

Licens fulltext: CC BY 4.0

Available from: 2023-08-17 Created: 2023-08-17 Last updated: 2023-09-05Bibliographically approved
Öhrn, O., Sykam, K., Gawusu, S., Mensah, R. A., Försth, M., Shanmugam, V., . . . Das, O. (2023). Surface coated ZnO powder as flame retardant for wood: A short communication. Science of the Total Environment, 897, Article ID 165290.
Open this publication in new window or tab >>Surface coated ZnO powder as flame retardant for wood: A short communication
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2023 (English)In: Science of the Total Environment, ISSN 0048-9697, E-ISSN 1879-1026, Vol. 897, article id 165290Article in journal (Refereed) Published
Abstract [en]

In the present study, the ability of a coating of zinc oxide (ZnO) powder to improve the fire-safety of wood exposed to radiative heat flux was examined, focusing on the ignition time of the wood. To test ZnO's efficiency on the wood substrate, two different amounts of ZnO (0.5 and 1 g ZnO per dm2) were applied to the wood surface and exposed to radiative heat from a cone calorimeter wherein a pristine piece of wood with no ZnO treatment was taken as control. The experiments were conducted at three different irradiation levels i.e., 20, 35, and 50 kWm−2. The results showed that applying ZnO on the surface of the wood significantly increased the ignition time (TTI). For the three different heat fluxes, using 0.5 g ZnO per dm2 coating on the wood surface increased the TTI by 26–33 %. Furthermore, the application of 1 g of ZnO per dm2 generated a TTI increment of 37–40 %. All three irradiation levels showed similar trends in TTI. The micrographs taken before and after combustion showed no significant disparity in the morphology of ZnO. The agglomerated ZnO particles on the wood surface remained intact after combustion. This study demonstrates a facile method of using ZnO to delay the ignition of wood. This could potentially impart fire-safety to wooden structures/façades in wildland-urban interfaces and elsewhere by reducing flame spread.

Place, publisher, year, edition, pages
Elsevier B.V., 2023
Keywords
Cone calorimeter, Fire, Flame retardancy, Wildland-urban interface, Wood, ZnO
National Category
Other Civil Engineering
Research subject
Structural Engineering
Identifiers
urn:nbn:se:ltu:diva-99288 (URN)10.1016/j.scitotenv.2023.165290 (DOI)37406703 (PubMedID)2-s2.0-85164736599 (Scopus ID)
Note

Validerad;2023;Nivå 2;2023-08-08 (joosat);

Licens fulltext: CC BY License

Available from: 2023-08-08 Created: 2023-08-08 Last updated: 2023-09-05Bibliographically approved
Sanned, E., Mensah, R. A., Försth, M. & Das, O. (2023). The curious case of the second/end peak in the heat release rate of wood: A cone calorimeter investigation. Fire and Materials, 47(4), 498-513
Open this publication in new window or tab >>The curious case of the second/end peak in the heat release rate of wood: A cone calorimeter investigation
2023 (English)In: Fire and Materials, ISSN 0308-0501, E-ISSN 1099-1018, Vol. 47, no 4, p. 498-513Article in journal (Refereed) Published
Abstract [en]

The reasons behind the occurrence of a second/end peak heat release rate (PHRR) during wood combustion under radiative heating were determined. Effects of the type of rear material, wood thickness, char progression, and its microstructure, as well as moisture content/transport in spruce wood, were studied. Rear materials used were insulating Kaowool, conducting steel, and the same wood but physically separated from test specimen by aluminium foil. The intensity of the second/end PHRR with Kaowool was almost 50% more than that of the sample with steel. Thus, the second/end peak is governed by the boundary condition defined by the rear material, which determines the heat losses at the rear side of the specimen and consequently the temperature of the specimen. Higher specimen temperature enhances the pyrolysis rate, thereby causing the second/end PHRR. The appearance times and values of the second/end PHRR for 30, 20, and 10 mm wood were 1740 s/78 kWm−2, 685 s/134 kWm−2, and 450 s/160 kWm−2, respectively. Char progressed to the rear of the samples even with a thin (8 mm) conductive steel substrate. Cracks in char grew almost three times wider during the second/end PHRR compared to the sample with no second/end peak. Char cracking had no significance on the time of occurrence of the second/end PHRR but affected the overall heat release. High moisture content reduced the charring rate and delayed the time of occurrence of the second/end PHRR as more water was needed to undergo a phase change, requiring a higher amount of energy.

Place, publisher, year, edition, pages
Wiley, 2023
Keywords
char formation, cone calorimetry, fire test, heat release rate, wood
National Category
Other Civil Engineering
Research subject
Structural Engineering
Identifiers
urn:nbn:se:ltu:diva-95276 (URN)10.1002/fam.3122 (DOI)000898495300001 ()2-s2.0-85143741733 (Scopus ID)
Note

Validerad;2023;Nivå 2;2023-06-29 (sofila);

Available from: 2023-01-16 Created: 2023-01-16 Last updated: 2023-09-05Bibliographically approved
Mensah, R. A., Shanmugam, V., Narayanan, S., Renner, J. S., Babu, K., Neisiany, R. E., . . . Das, O. (2022). A review of sustainable and environment-friendly flame retardants used in plastics. Polymer testing, 108, Article ID 107511.
Open this publication in new window or tab >>A review of sustainable and environment-friendly flame retardants used in plastics
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2022 (English)In: Polymer testing, ISSN 0142-9418, E-ISSN 1873-2348, Vol. 108, article id 107511Article in journal (Refereed) Published
Abstract [en]

The progressive transition from conventional structural designs to lightweight and more complex structures has led to the increase in the quantity of plastic materials in buildings. However, plastics have a major flaw: their low fire performance characterised by shorter ignition times and higher heat release rates. This has necessitated the incorporation of flame retardants (FRs) in plastics. Nevertheless, not all FRs are environmentally safe, hence, there is an urgent need for the development of sustainable biobased FRs that reduce environmental footprints while simultaneously improving the fire performance of plastics. This article addresses the negative connotation of FRs and reviews the most extensively used biobased FRs in plastics, their preparation (synthesis) and mode of application, performance evaluation as well as the leaching of FRs, and environmental fate. Some interesting observations in the review are the reduction of ignition times of plastics by the addition of FRs due to the rapid volatilisation of samples. In addition, the leaching rate of FRs is found to be higher in finer particles (micro and nanoparticles) compared to larger-sized ones and has the potential to dissolve in humic matter hence endangering the lives of humans and animals.

Place, publisher, year, edition, pages
Elsevier, 2022
Keywords
Sustainability, Flame retardants, Fire safety, Plastics, Environmental safety
National Category
Environmental Analysis and Construction Information Technology Composite Science and Engineering
Research subject
Structural Engineering
Identifiers
urn:nbn:se:ltu:diva-89585 (URN)10.1016/j.polymertesting.2022.107511 (DOI)000765513200012 ()2-s2.0-85124532435 (Scopus ID)
Note

Validerad;2022;Nivå 2;2022-03-16 (johcin)

Available from: 2022-03-16 Created: 2022-03-16 Last updated: 2023-09-05Bibliographically approved
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Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0002-7140-4737

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