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Morén, Tom
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Publications (10 of 82) Show all publications
Ahmed, S. A., Morén, T., Sehlstedt-Persson, M. & Blom, Å. (2017). Effect of oil impregnation on water repellency, dimensional stability and mold susceptibility of thermally-modified European aspen and downy birch wood. Journal of Wood Science, 63(1), 74-82
Open this publication in new window or tab >>Effect of oil impregnation on water repellency, dimensional stability and mold susceptibility of thermally-modified European aspen and downy birch wood
2017 (English)In: Journal of Wood Science, ISSN 1435-0211, E-ISSN 1611-4663, Vol. 63, no 1, p. 74-82Article in journal (Refereed) Published
Abstract [en]

Conventional chemical wood preservatives have been banned or restricted in some applications due to human and animal toxicity and their adverse impact on the surrounding environment. New, low-environmental-impact wood treatments that still provide effective protection systems are needed to protect wood. Thermal modification of wood could reduce hygroscopicity, improve dimensional stability and enhance resistance to mold attack. The aim of this study is to investigate if these properties enhanced in thermally-modified (TM) wood through treatments with oils. In this study, TM European aspen (Populus tremula) and downy birch (Betula pubescens) wood were impregnated with three different types of oil: water-miscible commercial Elit Träskydd (Beckers oil with propiconazole and 3-iodo-2-propynyl butylcarbamate, IPBC), a pine tar formulation and 100% tung oil. The properties of oil-impregnated wood investigated were water repellency, dimensional stability and mold susceptibility. The treated wood especially with pine tar and tung oil, showed an increase in water repellency and dimensional stability. However, Beckers oil which contains biocides like propiconazole and IPBC, showed better protection against mold compared with pine tar and tung oil. To enhance the dimensional stability of the wood, pine tar and tung oil can be used, but these oil treatments did not significantly improve mold resistance rather sometimes enhanced the mold growth. Whereas, a significant anti-mold effect was observed on Beckers oil treated samples.

Keywords
Thermal modification, oil impregnation, dimensional stability, durability, mold
National Category
Other Mechanical Engineering
Research subject
Wood Science and Engineering
Identifiers
urn:nbn:se:ltu:diva-60060 (URN)10.1007/s10086-016-1595-y (DOI)000394991100008 ()2-s2.0-84996656545 (Scopus ID)
Note

Validerad; 2017; Nivå 2; 2017-02-21 (rokbeg)

Available from: 2016-11-03 Created: 2016-10-31 Last updated: 2018-07-10Bibliographically approved
Couceiro, J., Vikberg, T., Hansson, L. & Morén, T. (2016). In Situ CT-Scanning of Checking and Collapse Behaviour of Eucalyptus nitens During Drying. In: Proceedings of the 59th International Convention of Society of Wood Science and Technology March 6-10, 2016 – Curitiba, Brazil: . Paper presented at 59th International Convention of Society of Wood Science and Technology, Curitiba, Brazil, March 6-10, 2016.
Open this publication in new window or tab >>In Situ CT-Scanning of Checking and Collapse Behaviour of Eucalyptus nitens During Drying
2016 (English)In: Proceedings of the 59th International Convention of Society of Wood Science and Technology March 6-10, 2016 – Curitiba, Brazil, 2016Conference paper, Published paper (Other academic)
Abstract [en]

Eucalyptus nitens has become a commercially important species in Chile and it isrepresenting one of the fastest growing wood-stock in the country. Today, it is widelyused for pulp and paper production, but the interest in using the solid wood has increasedin recent years. Before the sawn timber can be utilized, its moisture content must bereduced. Often during drying, hydrostatic tension forces within the cell exceed thecompressive strength of the thin cell wall of Eucalyptus nitens and the cell collapses. Thisphenomenon usually leads to severe surface deformation and both surface and internalcracks (honeycombing). Yield and quality of the final product, and thereby sawmills’profitability, are decreased by these cracks and deformations. The aim of this study wasto investigate, by CT-scanning samples throughout the drying process, if it is possible todetect when and how cracking and deformation occurs and develops in specimens ofEucalyptus nitens from Chile. Based on this knowledge, better drying schedules canhopefully be developed to improve the yield and provide a higher end-quality of the sawntimber.

Keywords
CT-scanning, Eucalyptus nitens, wood drying, image processing, cell collapse
National Category
Other Mechanical Engineering
Research subject
Wood Science and Engineering
Identifiers
urn:nbn:se:ltu:diva-61768 (URN)
Conference
59th International Convention of Society of Wood Science and Technology, Curitiba, Brazil, March 6-10, 2016
Available from: 2017-02-02 Created: 2017-02-01 Last updated: 2018-05-22Bibliographically approved
Vikberg, T. & Mornén, T. (2015). Internal Heat Exchange in Progressive Kilns (ed.). Pro Ligno, 11(4), 318-323
Open this publication in new window or tab >>Internal Heat Exchange in Progressive Kilns
2015 (English)In: Pro Ligno, ISSN 1841-4737, E-ISSN 2069-7430, Vol. 11, no 4, p. 318-323Article in journal (Refereed) Published
Abstract [en]

In this work possible energy savings were investigated by introducing a new layout of a 2-zone progressive kiln. The layout consisted of installing a door between the first and second zone, thereby allowing the two zones to be run at different temperature levels -making internal heat recovery possible. An Optimized Two Stage continuous kiln is dimensioned for drying sideboard of Norway spruce (Picea abies L. Karst) with the aid of a commercial simulation program. Temperature levels of 75/55°C (dry bulb/wet bulb) were chosen at the pressure side of zone 1 and 45/25°C (dry bulb/wet bulb) at the pressure side of zone 2. The capacity of the heat exchanger was assumed to be sufficient to make the suggested design functional and no consideration was given to the increased air flow resistance the introduction of the heat exchanger would cause. The results indicated that roughly 30% of the heat is possible to recover in comparison to a traditional kiln. It was finally concluded that the influence of ingoing process parameters needs to be implemented in the kiln control system to fully utilize the kilns potential.

National Category
Bio Materials Other Mechanical Engineering
Research subject
Wood Science and Engineering
Identifiers
urn:nbn:se:ltu:diva-5321 (URN)3636303a-3313-4c4b-8762-7e475e8d4b03 (Local ID)3636303a-3313-4c4b-8762-7e475e8d4b03 (Archive number)3636303a-3313-4c4b-8762-7e475e8d4b03 (OAI)
Note

Validerad; 2016; Nivå 1; 20151214 (tomvik)

Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2017-11-24Bibliographically approved
Ahmed, S. A., Yang, Q., Sehlstedt-Persson, M. & Morén, T. (2013). Accelerated mold test on dried pine sapwood boards: Impact of contact heat treatment (ed.). Paper presented at . Journal of wood chemistry and technology, 33(3), 174-187
Open this publication in new window or tab >>Accelerated mold test on dried pine sapwood boards: Impact of contact heat treatment
2013 (English)In: Journal of wood chemistry and technology, ISSN 0277-3813, E-ISSN 1532-2319, Vol. 33, no 3, p. 174-187Article in journal (Refereed) Published
Abstract [en]

We test the hypothesis that the combination of kiln drying of double-stacked boards and contact heat treatment will reduce the susceptibility of treated boards to colonization by mold fungi. Winter-felled Scots pine (Pinus sylvestris L.) sapwood boards were double-stacked in an industrial kiln in ‘‘sapwood out’’ and ‘‘sapwood in’’ positions. Dried samples were then contact heat-treated using a hot press at three different temperatures (140°C, 170°C, and 200°C) for three different periods (1, 3, and 10 min). Accelerated mold test was performed in a climate chamber where naturally mold infected samples were used as a source of mold inocula. Contact heat treatment degraded the saccharides which accumulated at dried surfaces, and reduced the mold growth. The threshold temperature and time for inhibiting mold growth was 170°C for 10 min. But, for industrial application, the most feasible combination of temperature and time would be 200°C for 3 min. We concluded that double stacking/contact heat treatment used is an environmentally friendly alternative to chemicals for reducing mold on Scots pine sapwood boards.

National Category
Bio Materials
Research subject
Wood Physics
Identifiers
urn:nbn:se:ltu:diva-15844 (URN)10.1080/02773813.2013.773041 (DOI)000317716000002 ()2-s2.0-84876728788 (Scopus ID)f674f798-5b6a-4559-8fb7-e49ce44b09d5 (Local ID)f674f798-5b6a-4559-8fb7-e49ce44b09d5 (Archive number)f674f798-5b6a-4559-8fb7-e49ce44b09d5 (OAI)
Note
Validerad; 2013; 20130129 (sheahm)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
Ahmed, S. A., Morén, T., Hagman, O., Cloutier, A., Fang, C.-H. & Elustondo, D. (2013). Anatomical properties and process parameters affecting blister/blow formation in densified European aspen and downy birch sapwood boards by thermo-hygro-mechanical compression (ed.). Paper presented at . Journal of Materials Science, 48(24), 8571-8579
Open this publication in new window or tab >>Anatomical properties and process parameters affecting blister/blow formation in densified European aspen and downy birch sapwood boards by thermo-hygro-mechanical compression
Show others...
2013 (English)In: Journal of Materials Science, ISSN 0022-2461, E-ISSN 1573-4803, Vol. 48, no 24, p. 8571-8579Article in journal (Refereed) Published
Abstract [en]

Approximately, 13.5 % of the standing volume of productive forest land in Sweden is covered by birch and aspen, which provides the vast potential to produce value-added products such as densified wood. This study shows whether it is possible to densify those species with a thermo-hygro-mechanical (THM) process using heat, steam, and pressure. In this process, transverse compression on thin European aspen (Populus tremula) and downy birch (Betula pubescens) boards was performed at 200 ºC with a maximum steam pressure of 550 kPa. To obtain a theoretical 50 % compression set, the press’s maximum hydraulic pressure ranged from 1.5 to 7.3 MPa. Preliminary tests showed that ~75 % of the birch boards produced defects (blisters/blows) while only 25 % of the aspen boards did. Mainly, radial delamination associated with internal checks in intrawall and transwall fractures caused small cracks (termed blisters) while blows are characterized by relatively larger areas of delamination visible as a bumpy surface on the panel. Anatomical investigations revealed that birch was more prone to those defects than aspen. However, those defects could be minimized by increasing the pre-treatment time during the THM processing.

National Category
Bio Materials Other Mechanical Engineering
Research subject
Wood Physics; Wood Products Engineering
Identifiers
urn:nbn:se:ltu:diva-7066 (URN)10.1007/s10853-013-7679-9 (DOI)000324111700028 ()2-s2.0-84891903228 (Scopus ID)5618af53-b6b8-496d-a902-97c101649a98 (Local ID)5618af53-b6b8-496d-a902-97c101649a98 (Archive number)5618af53-b6b8-496d-a902-97c101649a98 (OAI)
Note
Validerad; 2013; 20130823 (sheahm)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
Ahmed, S. A., Sehlstedt-Persson, M. & Morén, T. (2013). Development of a new rapid method for mould testing in a climate chamber: Preliminary tests (ed.). Paper presented at . European Journal of Wood and Wood Products, 71(4), 451-461
Open this publication in new window or tab >>Development of a new rapid method for mould testing in a climate chamber: Preliminary tests
2013 (English)In: European Journal of Wood and Wood Products, ISSN 0018-3768, E-ISSN 1436-736X, Vol. 71, no 4, p. 451-461Article in journal (Refereed) Published
Abstract [en]

The purpose of this study was to develop fast, simple and robust solid wood mould testing methods for the use in small-scale laboratory tests. The objective was to investigate mould susceptibility of different wood materials within the batches. The proposed method is based on natural contamination of non-sterile surfaces in climates conducive to mould growth. For this purpose, a climate chamber with regulated temperature and relative humidity was used. The conditioning chamber was divided into upper and lower chamber by a thin layer of stainless steel placed horizontally above the fan to minimise air circulation to the sample in the upper compartment. Mould-infected samples from outdoor tests were used as a source of mould inocula, and test trials were conducted on Scots pine (Pinus sylvestris L.) sapwood. Samples were suspended from the top of the upper chamber, and the chamber was exposed to different temperature and humidity levels. Severe mould infestation was observed after 12-14 days of incubation. Visual mould rating was then performed. Regardless of some constraints, this test method was very simple, fast, and effective. More importantly, unlike other test methods, it closely models mould infestation as it would occur under natural condition.

National Category
Bio Materials
Research subject
Wood Physics
Identifiers
urn:nbn:se:ltu:diva-8083 (URN)10.1007/s00107-013-0697-0 (DOI)000320376800006 ()2-s2.0-84879217007 (Scopus ID)685a5886-bee5-4256-9062-40b0ed78c195 (Local ID)685a5886-bee5-4256-9062-40b0ed78c195 (Archive number)685a5886-bee5-4256-9062-40b0ed78c195 (OAI)
Note
Validerad; 2013; 20130423 (sheahm)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
Yang, Q., Karlsson, O., Ahmed, S. A. & Morén, T. (2013). Dimensional stability and water repellency of european aspen improved by oxidized carbohydrates (ed.). Paper presented at . BioResources, 8(1), 487-498
Open this publication in new window or tab >>Dimensional stability and water repellency of european aspen improved by oxidized carbohydrates
2013 (English)In: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 8, no 1, p. 487-498Article in journal (Refereed) Published
Abstract [en]

Small samples from European aspen (Populus tremula L.) were impregnated with carbohydrates oxidized by Fenton’s reagent using water in a vacuum, followed by heating in an oven at 103°C. An antiswelling efficiency (ASE) of around 45% for wood treated with oxidized glucose and 35% for wood treated with oxidized sucrose was obtained. Samples treated with oxidized carbohydrates gave water repellent effectiveness (WRE) values over 35%. The decrease in cell wall thickness during impregnation was about 18% less in the presence of oxidized glucose than samples only treated with Fenton’s reagent. An ASE of 20% for the wood samples that had been treated with oxidized glucose was obtained after 7 days of soaking in water. The reasons for the improvement in dimensional stability are discussed in this work.

National Category
Bio Materials
Research subject
Wood Physics
Identifiers
urn:nbn:se:ltu:diva-9532 (URN)82f3919a-d280-4cb6-8abd-f69eb96bc438 (Local ID)82f3919a-d280-4cb6-8abd-f69eb96bc438 (Archive number)82f3919a-d280-4cb6-8abd-f69eb96bc438 (OAI)
Note
Validerad; 2013; 20130129 (sheahm)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2017-11-24Bibliographically approved
Ahmed, S. A., Hansson, L. & Morén, T. (2013). Distribution of preservatives in thermally modified Scots pine and Norway spruce sapwood (ed.). Paper presented at . Wood Science and Technology, 47(3), 499-513
Open this publication in new window or tab >>Distribution of preservatives in thermally modified Scots pine and Norway spruce sapwood
2013 (English)In: Wood Science and Technology, ISSN 0043-7719, E-ISSN 1432-5225, Vol. 47, no 3, p. 499-513Article in journal (Refereed) Published
Abstract [en]

Studying the impregnation and distribution of oil-based preservative in dried wood is complicated as wood is a nonhomogeneous, hygroscopic and porous material, and especially of anisotropic nature. However, this study is important since it has influence on the durability of wood. To enhance the durability of thermally modified wood, a new method for preservative impregnation is introduced, avoiding the need for external pressure or vacuum. This article presents a study on preservative distribution in thermally treated Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies (L.) Karst.) sapwood using computed tomography scanning, light microscopy, and scanning electron microscopy. Secondary treatment of thermally modified wood was performed on a laboratory scale by impregnation with two types of preservatives, viz. Elit Träskydd (Beckers) and pine tar (tar), to evaluate their distribution in the wood cells. Preservative solutions were impregnated in the wood using a simple and effective method. Samples were preheated to 170°C in a drying oven and immediately submerged in preservative solutions for simultaneous impregnation and cooling. Tar penetration was found higher than Beckers, and their distribution decreased with increasing sample length. Owing to some anatomical properties, uptake of preservatives was low in spruce. Besides, dry-induced interstitial spaces, which are proven important flow paths for seasoned wood, were not observed in this species.

National Category
Bio Materials
Research subject
Wood Physics
Identifiers
urn:nbn:se:ltu:diva-10629 (URN)10.1007/s00226-012-0509-4 (DOI)000318292900005 ()2-s2.0-84877828892 (Scopus ID)9759fb33-caeb-4495-80d5-0bcb79063304 (Local ID)9759fb33-caeb-4495-80d5-0bcb79063304 (Archive number)9759fb33-caeb-4495-80d5-0bcb79063304 (OAI)
Note
Validerad; 2013; 20121009 (sheahm)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
Ahmed, S. A., Sehlstedt-Persson, M., Hansson, L. & Morén, T. (2013). Evaluation of preservative distribution in thermally modified European aspen and birch boards using computed tomography and scanning electron microscopy (ed.). Paper presented at . Journal of Wood Science, 59(1), 57-66
Open this publication in new window or tab >>Evaluation of preservative distribution in thermally modified European aspen and birch boards using computed tomography and scanning electron microscopy
2013 (English)In: Journal of Wood Science, ISSN 1435-0211, E-ISSN 1611-4663, Vol. 59, no 1, p. 57-66Article in journal (Refereed) Published
Abstract [en]

The aim of this experiment was to impregnate thermally modified wood using an easy and cost-effective method. Industrially processed thermally modified European aspen (Populus tremula L.) and birch (Betula pubescens Ehrh.) were collected and secondarily treated at the laboratory scale with the preservatives tung oil, pine tar and Elit Träskydd (Beckers) using a simple and effective method. Preservative uptake and distribution in sample boards were evaluated using computed tomography (CT) and scanning electron microscopy (SEM) techniques. Preservative uptake and treatability in terms of void volume filled were found the highest in Beckers and the lowest in tung oil-treated samples. Thermally modified samples had lower treatability than their counterpart control samples. More structural changes after thermal modification, especially in birch, significantly reduced the preservative uptake and distribution. The differences of preservatives uptake near the end grain were high and then decreased near the mid position of the samples length as compared with similar type of wood sample. Non-destructive evaluation by CT scanning provided a very useful method to locate the preservative gradients throughout the sample length. SEM analysis enabled the visualization of the preservative deposits in wood cells at the microstructural level.

National Category
Bio Materials
Research subject
Wood Physics
Identifiers
urn:nbn:se:ltu:diva-7179 (URN)10.1007/s10086-012-1299-x (DOI)000315037000008 ()2-s2.0-84874105544 (Scopus ID)5807e96a-4097-4c82-9f68-31f9f6386aee (Local ID)5807e96a-4097-4c82-9f68-31f9f6386aee (Archive number)5807e96a-4097-4c82-9f68-31f9f6386aee (OAI)
Note
Validerad; 2013; 20121022 (sheahm)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
Ahmed, S. A., Sehlstedt-Persson, M. & Morén, T. (2013). Mould susceptibility of Scots pine (Pinus sylvestris L.) sapwood: Impact of drying, thermal modification, and copper-based preservative (ed.). Paper presented at . International Biodeterioration & Biodegradation, 85, 284-288
Open this publication in new window or tab >>Mould susceptibility of Scots pine (Pinus sylvestris L.) sapwood: Impact of drying, thermal modification, and copper-based preservative
2013 (English)In: International Biodeterioration & Biodegradation, ISSN 0964-8305, E-ISSN 1879-0208, Vol. 85, p. 284-288Article in journal (Refereed) Published
Abstract [en]

The development of mould on wood surfaces depends on several factors. Although mould does not affect the mechanical properties of wood, it greatly reduces the aesthetic value of wood like the sapwood of Scots pine (Pinus sylvestris L.), which is very prone to mould. In addition, adverse health effects of mould on humans are also a great concern. Different types of dried and treated wood were used to observe whether they had enhanced durability against mould following an accelerated laboratory test method in a climate chamber. Samples were green, air-dried, industrially thermally-modified, treated with copper-based preservative, and kiln-dried wood, which were tested within a single test run. The test produced the following main results: the thermal modification increased the durability of the wood, and the protective effectiveness of alternative treatments was comparable to that of commercially available copper-based treatment. However, the initial moisture content of the samples during mould exposure had a great influence on the onset of mould growth. The risk of mould susceptibility of industrial kiln-dried lumber can be reduced by drying using the double-layering technique which likely forced the nutrients to deposit near the evaporation surfaces followed by planing off the nutrient enriched edges.

National Category
Bio Materials
Research subject
Wood Physics
Identifiers
urn:nbn:se:ltu:diva-12380 (URN)10.1016/j.ibiod.2013.06.031 (DOI)000327166300039 ()2-s2.0-84884246330 (Scopus ID)b84bb295-5eee-4f48-babb-1a3ab3acb148 (Local ID)b84bb295-5eee-4f48-babb-1a3ab3acb148 (Archive number)b84bb295-5eee-4f48-babb-1a3ab3acb148 (OAI)
Note
Validerad; 2013; 20130607 (sheahm)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
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