Change search
Link to record
Permanent link

Direct link
BETA
Segerholm, KristofferORCID iD iconorcid.org/0000-0001-7014-6230
Alternative names
Publications (10 of 45) Show all publications
Joffre, T., Segerholm, K., Persson, C., Bardage, S. L., Hendriks, C. L. L. & Isaksson, P. (2017). Characterization of interfacial stress transfer ability in acetylation-treated wood fibre composites using, X-ray microtomography. INDUSTRIAL CROPS AND PRODUCTS, 95, 43-49
Open this publication in new window or tab >>Characterization of interfacial stress transfer ability in acetylation-treated wood fibre composites using, X-ray microtomography
Show others...
2017 (English)In: INDUSTRIAL CROPS AND PRODUCTS, ISSN 0926-6690, Vol. 95, p. 43-49Article in journal (Refereed) Published
Abstract [en]

The properties of the fibre/matrix interface contribute to stiffness, strength and fracture behaviour of fibre-reinforced composites. In cellulosic composites, the limited affinity between the hydrophilic fibres and the hydrophobic thermoplastic matrix remains a challenge, and the reinforcing capability of the fibres is hence not fully utilized. A direct characterisation of the stress transfer ability through pull-out tests on single fibres is extremely cumbersome due to the small dimension of the wood fibres. Here a novel approach is proposed: the length distribution of the fibres sticking out of the matrix at the fracture surface is approximated using X-ray microtomography and is used as an estimate of the adhesion between the fibres and the matrix. When a crack grows in the material, the fibres will either break or be pulled-out of the matrix depending on their adhesion to the matrix: good adhesion between the fibres and the matrix should result in more fibre breakage and less pull-out of the fibres than poor adhesion. The effect of acetylation on the adhesion between the wood fibres and the PLA matrix was evaluated at different moisture contents using the proposed method. By using an acetylation treatment of the fibres it was possible to improve the strength of the composite samples soaked in the water by more than 30%.

Place, publisher, year, edition, pages
Elsevier, 2017
Keywords
CT analysis, Wood fibres, PLA, Adhesion, Acetylation
National Category
Environmental Sciences related to Agriculture and Land-use
Identifiers
urn:nbn:se:kth:diva-200197 (URN)10.1016/j.indcrop.2016.10.009 (DOI)000390621600006 ()2-s2.0-84991689339 (Scopus ID)
Note

QC 20170202

Available from: 2017-02-02 Created: 2017-01-23 Last updated: 2018-01-13Bibliographically approved
Laine, K., Segerholm, K., Wålinder, M., Rautkari, L., Hughes, M. & Lankveld, C. (2016). Surface densification of acetylated wood. European Journal of Wood and Wood Products, 74(6), 829-835
Open this publication in new window or tab >>Surface densification of acetylated wood
Show others...
2016 (English)In: European Journal of Wood and Wood Products, ISSN 0018-3768, E-ISSN 1436-736X, Vol. 74, no 6, p. 829-835Article in journal (Refereed) Published
Abstract [en]

The mechanical properties of wood can be improved by compressing its porous structure between heated metal plates. By adjusting the process parameters it is possible to target the densification only in the surface region of wood where the property improvements are mostly needed in applications, such as flooring. The compressed form is, however, sensitive to moisture and will recover to some extent in high humidity. In this study, therefore, acetylated radiata pine was utilised in the surface densification process in order to both reduce the set-recovery of densified wood and to improve the hardness of the acetylated wood. Pre-acetylation was found to significantly reduce the set-recovery of surface densified wood. However, after the second cycle the increase in set-recovery of acetylated wood was relatively higher than the un-acetylated wood. The acetylated samples were compressed by only 1 mm (instead of the target 2 mm), yet, the hardness and hardness recovery of the acetylated samples significantly increased as a result of densification. It was also discovered that rough (un-planed) surfaces may be surface densified, however, even if the surface became smooth to the touch, the appearance remained uneven.

Place, publisher, year, edition, pages
Springer, 2016
Keywords
Acetylation, Densification, Hardness, Recovery, Acetylated wood, Densified wood, Mechanical properties of wood, Porous structures, Process parameters, Property improvement, Surface densification, Surface region, Wood
National Category
Materials Engineering
Identifiers
urn:nbn:se:kth:diva-195233 (URN)10.1007/s00107-016-1077-3 (DOI)000385208400005 ()2-s2.0-84976477767 (Scopus ID)
Note

QC 20161117

Available from: 2016-11-17 Created: 2016-11-02 Last updated: 2017-11-29Bibliographically approved
Ruponen, J., Kimpimäki, S., Rohumaa, A., Laine, K., Segerholm, K., Wålinder, M., . . . Hughes, M. (2016). Tensile-shear strength studies on self-bonded 2-ply birch veneer joint manufactured and tested by applying Automated Bonding Evaluation System (ABES) hot press. In: WCTE 2016 - World Conference on Timber Engineering: . Paper presented at 2016 World Conference on Timber Engineering, WCTE 2016, 22 August 2016 through 25 August 2016. Vienna University of Technology
Open this publication in new window or tab >>Tensile-shear strength studies on self-bonded 2-ply birch veneer joint manufactured and tested by applying Automated Bonding Evaluation System (ABES) hot press
Show others...
2016 (English)In: WCTE 2016 - World Conference on Timber Engineering, Vienna University of Technology , 2016Conference paper, Published paper (Refereed)
Abstract [en]

An Automatic Bond Evaluation System (ABES) hot press was employed to manufacture a self-bonded joint between two veneers of rotary-cut birch (Betula pendula Roth). The hot-pressing conditions were 220 °C and 5.0 MPa, with press times ranging from 180 s to 600 s with 60 s intervals. Additionally, the log-soaking temperature (20 °C and 70 °C) and the veneer initial MC (6% and 11%) were varied to study the effect on the tensile-shear strength of the joints. For one set, the surface properties were altered by acetone extraction. The samples were tested at 11% MC. However, one set was partly duplicated and tested at 6% MC, to study how the testing conditions influenced the bond strength. The maximum average tensile-shear strength was 3.3 MPa, observed after 600 s hot pressing. The studies also included bond-line micromorphology analysis by applying SEM combined with a micromachining surface preparation technique based on UV excimer laser ablation. It was also indicated that longer hot-pressing times, lower veneer initial MC and a lower testing MC resulted in increased tensile-shear strength. Acetone extraction decreased the bond strength with increased standard deviation. Finally, the highest single and average strengths were observed for veneers from higher soaking temperature.

Place, publisher, year, edition, pages
Vienna University of Technology, 2016
Keywords
ABES, Birch, Laser ablation, Self-bonding, SEM, Soaking temperature, Tensile-shear strength, Veneer, Ablation, Acetone, Bond strength (materials), Excimer lasers, Extraction, Hot pressing, Presses (machine tools), Scanning electron microscopy, Shear flow, Tensile testing, Thermal logging, Timber, Veneers, Self bonding, Tensile shear strength, Tensile strength
National Category
Materials Engineering
Identifiers
urn:nbn:se:kth:diva-207528 (URN)2-s2.0-85010960673 (Scopus ID)9783903039001 (ISBN)
Conference
2016 World Conference on Timber Engineering, WCTE 2016, 22 August 2016 through 25 August 2016
Note

Conference code: 124667; Export Date: 22 May 2017; Conference Paper. QC 20170531

Available from: 2017-05-31 Created: 2017-05-31 Last updated: 2017-05-31Bibliographically approved
Laine, K., Segerholm, K., Wålinder, M., Rautkari, L. & Hughes, M. (2016). Wood densification and thermal modification: hardness, set-recovery and micromorphology. Wood Science and Technology, 50(5), 883-894
Open this publication in new window or tab >>Wood densification and thermal modification: hardness, set-recovery and micromorphology
Show others...
2016 (English)In: Wood Science and Technology, ISSN 0043-7719, E-ISSN 1432-5225, Vol. 50, no 5, p. 883-894Article in journal (Refereed) Published
Abstract [en]

The density of wood can be increased by compressing the porous structure under suitable moisture and temperature conditions. One aim of such densification is to improve surface hardness, and therefore, densified wood might be particularly suitable for flooring products. After compression, however, the deformed wood material is sensitive to moisture, and in this case, recovered up to 60 % of the deformation in water-soaking. This phenomenon, termed set-recovery, was reduced by thermally modifying the wood after densification. This study presents the influence of compression ratio (CR = 40, 50, 60 %) and thermal modification time (TM = 2, 4, 6 h) on the hardness and set-recovery of densified wood. Previously, set-recovery has mainly been studied separately from other properties of densified wood, while in this work, set-recovery was also studied in relation to hardness. The results show that set-recovery was almost eliminated with TM 6 h in the case of CR 40 and 50 %. Hardness significantly increased due to densification and even doubled compared to non-densified samples with a CR of 50 %. Set-recovery reduced the hardness of densified (non-TM) wood back to the original level. TM maintained the hardness of densified wood at an increased level after set-recovery. However, some reduction in hardness was recorded even if set-recovery was almost eliminated.

Place, publisher, year, edition, pages
Springer, 2016
National Category
Wood Science
Identifiers
urn:nbn:se:kth:diva-196446 (URN)10.1007/s00226-016-0835-z (DOI)000385253100002 ()2-s2.0-84969895593 (Scopus ID)
Note

QC 20161129

Available from: 2016-11-29 Created: 2016-11-14 Last updated: 2017-11-29Bibliographically approved
Källbom, S., Wålinder, M., Segerholm, K. & Jones, D. (2015). Surface energy characterization of thermally modified spruce using inverse gas chromatography under cyclic humidity conditions. Wood and Fiber Science, 47(4), 410-420
Open this publication in new window or tab >>Surface energy characterization of thermally modified spruce using inverse gas chromatography under cyclic humidity conditions
2015 (English)In: Wood and Fiber Science, ISSN 0735-6161, Vol. 47, no 4, p. 410-420Article in journal (Refereed) Published
Abstract [en]

The surface energy of unmodified and thermally modified spruce wood components was researched at dry and moist conditions using inverse gas chromatography. The results indicate a more pronounced heterogeneous nature of the thermally modified wood surfaces in terms of the dispersive (nonpolar) component of the surface energy, compared with that of the unmodified wood surfaces. The dispersive component of the surface energy of the thermally modified wood ranged between 44 and 38 mJ/m(2) corresponding to an increase in surface coverage from a low level and up to about 10%. Suggested explanations for the more distinct heterogeneity of the thermally modified wood sample are related to chemical changes of the wood substance which seem to result in certain micromorphological features observed by scanning electron microscopy as alternated fracture surfaces created in the grinding process; and also possible changes or redistribution of the wood extractives. An increase of the MC, representing a change from a dry condition of approximately 0% RH to ca 75% RH, of both the unmodified and thermally modified samples seemed to have a marginal influence on the dispersive component of the surface energy. Possible implications of the results in this study can be found in the tailoring of new compatible and durable material combinations, for example, when using thermally modified wood residuals as a component in new types of biocomposites.

Place, publisher, year, edition, pages
SOC WOOD SCI TECHNOL, 2015
Keywords
Thermally modified wood, inverse gas chromatography, humidity cycling, Norway spruce, dispersive surface energy, surface energy heterogeneity, BET-specific surface area
National Category
Materials Engineering
Research subject
Civil and Architectural Engineering
Identifiers
urn:nbn:se:kth:diva-172956 (URN)000363992000011 ()2-s2.0-84991704745 (Scopus ID)
Funder
Swedish Research Council Formas, EnWoBio 2014-172
Note

QC 20151202

Forskningsfinansiärer: Stiftelsen Nils och Dorthi Troëdssons forskningsfond (Projektnr 793/12 Hydro-termo-mekanisk modifiering av trä). EcoBuild Institute Excellence Centre

Available from: 2015-09-04 Created: 2015-09-03 Last updated: 2018-08-24Bibliographically approved
Laine, K., Segerholm, K., Wålinder, M., Rautkari, L., Ormondroyd, G., Hughes, M. & Jones, D. (2014). Micromorphological studies of surface densified wood. Journal of Materials Science, 49(5), 2027-2034
Open this publication in new window or tab >>Micromorphological studies of surface densified wood
Show others...
2014 (English)In: Journal of Materials Science, ISSN 0022-2461, E-ISSN 1573-4803, Vol. 49, no 5, p. 2027-2034Article in journal (Refereed) Published
Abstract [en]

Scots pine (Pinus sylvestris L.) wood was surface densified in its radial direction in an open press with one heated plate to obtain a higher density on the wood surface whilst retaining the overall thickness of the sample. This study investigated the effect of temperature (100, 150 and 200 A degrees C) and press closing speed (5, 10 and 30 mm/min, giving closing times of 60, 30 and 10 s, respectively) on the micromorphology of the cell-wall, as well as changes occurring during set-recovery of the densified wood. The micromorphology was analysed using scanning electron microscopy (SEM) combined with a sample preparation technique based on ultraviolet-excimer laser ablation. Furthermore, the density profiles of the samples were measured. Low press temperature (100 A degrees C) and short closing time (10 s) resulted in more deformation through the whole thickness, whilst increasing the temperature (150 and 200 A degrees C) and prolonging the closing time (30 and 60 s) enabled more targeted deformation closer to the heated plate. The deformation occurred in the earlywood regions as curling and twisting of the radial cell-walls, however, no apparent cell-wall disruption or internal fracture was observed, even at low temperatures and fast press closing speed, nor after soaking and drying of the samples. In the SEM-analysis after soaking and drying, it was noticed that the cells did not completely recover their original form. Thus, part of the deformation was considered permanent perhaps due to viscoelastic flow and plastic deformation of the cell-wall components.

Keywords
Modified Scots Pine, Process Parameters, High-Temperature, Density Profile, Laser-Ablation, Solid Wood, Densification, Recovery, Deformation, Compression
National Category
Materials Engineering
Identifiers
urn:nbn:se:kth:diva-140650 (URN)10.1007/s10853-013-7890-8 (DOI)000329247300012 ()2-s2.0-84892440881 (Scopus ID)
Note

QC 20140131

Available from: 2014-01-31 Created: 2014-01-30 Last updated: 2017-12-06Bibliographically approved
Källbom, S., Ormondroyd, G., Segerholm, K., Jones, D. & Wålinder, M. (2014). Surface energy characteristics of refined fibres at different pressures. In: Wilson, Peter (Ed.), Proceedings of 10th Meeting of the Northern European Network for Wood Science & Engineering (WSE 2014): . Paper presented at The 10th Annual Meeting of the Northern European Network for Wood Science & Engineering (WSE), 13-14 October 2014 (pp. 134-138).
Open this publication in new window or tab >>Surface energy characteristics of refined fibres at different pressures
Show others...
2014 (English)In: Proceedings of 10th Meeting of the Northern European Network for Wood Science & Engineering (WSE 2014) / [ed] Wilson, Peter, 2014, p. 134-138Conference paper, Published paper (Other academic)
Abstract [en]

Wood fibres were produced on the pilot scale refiner at the BioComposites Centre, Bangor University, from a commercially sourced mix of chipped wood. The fibres were produced at refiner pressure 4, 6, 8 and 10 bar and dried in the associated flash drier. Surface energy characterization of the refined fibres was performed using inverse gas chromatography (IGC). The dispersive part of the total surface energy was analysed for duplicates of fibre samples at the four different refiner pressures. Non-polar alkane probes were used for the dispersive surface energy analysis at different surface coverage. Results indicate that the processing pressure has an effect of the dispersive surface energy and IGC analysis could be developed as a tool both for process development and process control in refining fibres.

Keywords
Inverse gas chromatography, dispersive surface energy, refined fibres
National Category
Composite Science and Engineering Paper, Pulp and Fiber Technology
Identifiers
urn:nbn:se:kth:diva-172959 (URN)10.13140/2.1.2942.7201 (DOI)
Conference
The 10th Annual Meeting of the Northern European Network for Wood Science & Engineering (WSE), 13-14 October 2014
Note

QC 20150904

Available from: 2015-09-03 Created: 2015-09-03 Last updated: 2015-09-04Bibliographically approved
Källbom, S., Segerholm, K., Jones, D. & Wålinder, M. (2014). Surface energy characterization of thermally modified wood particles exposed to humidity cycling using inverse gas chromatography. In: Nunes, L., Jones, D., Hill, C. and Militz, H. (Ed.), : . Paper presented at The Seventh European Conference on Wood Modification (ECWM7)..
Open this publication in new window or tab >>Surface energy characterization of thermally modified wood particles exposed to humidity cycling using inverse gas chromatography
2014 (English)In: / [ed] Nunes, L., Jones, D., Hill, C. and Militz, H., 2014Conference paper, Poster (with or without abstract) (Other academic)
Abstract [en]

The objective of this work was to study surface energetics of thermally modified wood particles exposed to dry-humid cycling. This information can give insight in the adhesion properties between the modified wood and composite matrices, adhesives or coatings. The surface energy characterization as well as the dry-humid cycling was performed using inverse gas chromatography (IGC). Duplicates of thermally modified and unmodified spruce particles with size 0-0.125 mm were investigated and conditioned in dry-humid cycles at 0-75 % RH and 0‑25 % RH. The BET specific surface area as well as the dispersive surface energy heterogeneity (or distribution) at different surface coverage was determined. The results showed similar trends for the different cycles in the dry and humid states, respectively. The difference in dispersive surface energy distribution between the dry and humid state was more pronounced at the lower surface coverage.

Keywords
Humidity cycling, inverse gas chromatography (IGC), surface energy characterization, thermally modified wood
National Category
Composite Science and Engineering
Identifiers
urn:nbn:se:kth:diva-172957 (URN)
Conference
The Seventh European Conference on Wood Modification (ECWM7).
Funder
Knowledge FoundationSwedish Foundation for Strategic Research
Note

QC 20150904

Forskningsfinansiärer:

Stiftelsen Nils och Dorthi Troëdssons forskningsfond (Projektnr 793/12 Hydro-termo-mekanisk modifiering av trä)

EcoBuild Institute Excellence Centre 

Available from: 2015-09-03 Created: 2015-09-03 Last updated: 2015-09-04Bibliographically approved
Källbom, S., Rautkari, L., Wålinder, M., Jones, D. & Segerholm, K. (2014). Water vapour sorption properties and surface chemical analysis of thermally modified wood particles. In: Recent Advances in the field of TH and THM Wood Treatment: . Paper presented at Final meeting of COST Action FP0904 Conference in Skellefteå, Sweden..
Open this publication in new window or tab >>Water vapour sorption properties and surface chemical analysis of thermally modified wood particles
Show others...
2014 (English)In: Recent Advances in the field of TH and THM Wood Treatment, 2014Conference paper, Oral presentation with published abstract (Other academic)
Keywords
Dynamic vapour sorption, humidity cycling, wood modification, X-ray photoelectron spectroscopy (XPS)
National Category
Composite Science and Engineering
Identifiers
urn:nbn:se:kth:diva-172958 (URN)
Conference
Final meeting of COST Action FP0904 Conference in Skellefteå, Sweden.
Funder
Swedish Foundation for Strategic Research Knowledge Foundation
Note

QC 20150904

Forskningsfinansiärer:

COST Action FP0904

Stiftelsen Nils och Dorthi Troëdssons forskningsfond (Projektnr 793/12 Hydro-termo-mekanisk modifiering av trä)

EcoBuild Institute Excellence Centre

Available from: 2015-09-03 Created: 2015-09-03 Last updated: 2015-09-04Bibliographically approved
Segerholm, K. & Ibach, R. E. (2013). Moisture and Fungal Durability of Wood-Plastic Composites Made With Chemically Modified and Treated Wood Flour. In: Proceedings IRG Annual Meeting: . Paper presented at IRG Annual Meeting 2013; Stockholm, Sweden, 16-20 June, 2013 (pp. IRG/WP 13-40648).
Open this publication in new window or tab >>Moisture and Fungal Durability of Wood-Plastic Composites Made With Chemically Modified and Treated Wood Flour
2013 (English)In: Proceedings IRG Annual Meeting, 2013, p. IRG/WP 13-40648-Conference paper, Published paper (Refereed)
Abstract [en]

Evaluating the fungal durability of wood-plastic composites (WPCs) is complicated by the influence of slow moisture sorption. Recently, the American Wood Protection Association (AWPA) Standard Method E10, Testing Wood Preservatives by Laboratory Soil-Block Cultures, was modified to incorporate not only solid wood, but also wood-based composites and WPCs. To simulate long term WPC performance, conditioning of the specimens is now required prior to fungal exposure to increase the moisture content of the specimens. The moisture and fungal durability, as well as the mechanical properties, of two different WPCs were investigated in the laboratory following this new AWPA E10-12 Standard. Wood flour was modified with acetic anhydride and then extruded with high density polyethylene (HDPE). Wood flour was treated with an isothiazolone-based solution and then injected molded with polypropylene (PP). WPCs were conditioned by water soaking either 2 weeks at 22 ˚C or 5 days at 70 ˚C. Weight and moisture content of the WPCs were monitored. Results showed that the acetylation decreased the moisture sorption of the WPCs and showed no mass losses due to decay. The WPC with an isothiazolone-based solution did not show any mass losses due to fungal decay.

Keywords
wood-plastic composites, fungal durability, moisture resistance, acetylation, isothiazolone
National Category
Other Civil Engineering
Identifiers
urn:nbn:se:kth:diva-137965 (URN)
Conference
IRG Annual Meeting 2013; Stockholm, Sweden, 16-20 June, 2013
Note

QC 20140618

Available from: 2013-12-17 Created: 2013-12-17 Last updated: 2014-06-18Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0001-7014-6230

Search in DiVA

Show all publications