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  • 151.
    Sandberg, Ulf
    et al.
    VTI.
    Mioduszewski, Piotr
    Technical University of Gdansk.
    Ejsmont, Jerzy
    Technical University of Gdansk.
    Vieira, Tiago
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial. VTI.
    Noise and Rolling Resistance Properties of Various Types of Winter Tyres Compared to Normal Car Tyres2016Ingår i: Proceedings of the Inter-Noise 2016, German Acoustical Society (DEGA) , 2016, s. 1737-1746Konferensbidrag (Refereegranskat)
    Abstract [en]

    To cope with winter weather conditions, potentially including snow and ice, it is common to use winter tyres, or "all-seasons" tyres assumed to be safe both in summer and winter. In some northern countries, winter tyres are mandatory. It is commonly assumed that winter tyres are noisier than normal tyres (here called summer tyres) and winter tyres equipped with studs are assumed to be extra noisy. This paper presents a study where noise and rolling resistance properties of tyres for winter conditions are compared to summer and all-season tyres. The winter tyres include types optimized for central European climate, tyres optimized for Nordic climate and tyres with studs. In total, approx. 50 car tyres have been tested. Noise properties have been measured with the CPX method and rolling resistance has been measured with a trailer method; all measurements made on two road surfaces; SMA 8 and DAC 16. Results indicate that winter tyres are not noisier than summer tyres; except for studded tyres. Despite high differences among individual tyres, rolling resistance is approximately similar among the main types; surprisingly including also studded tyres. An alarming result was that there was no correlation between measured values and values on the tyre labels.

  • 152. Sedighi Moghaddam, M.
    et al.
    Wålinder, Magnus. E. P.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial.
    Claesson, Per Martin
    KTH, Skolan för kemivetenskap (CHE), Kemi, Yt- och korrosionsvetenskap.
    Swerin, Agne
    KTH, Skolan för kemivetenskap (CHE), Kemi, Yt- och korrosionsvetenskap.
    Multicycle wilhelmy plate method for wetting properties, swelling and liquid sorption of wood2013Ingår i: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 29, nr 39, s. 12145-12153Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A multicycle Wilhelmy plate method has been developed to investigate wetting properties, liquid sorption, and swelling of porous substrates such as wood. The use of the method is exemplified by studies of wood veneers of Scots pine sapwood and heartwood, which were subjected to repeated immersion and withdrawal in a swelling liquid (water) and in a nonswelling liquid (octane). The swelling liquid changes the sample dimensions during measurements, in particular its perimeter. This, in turn, influences the force registered. A model based on a linear combination of the measured force and final change in sample perimeter is suggested, and validated to elucidate the dynamic perimeter change of wood veneer samples. We show that pine heartwood and pine sapwood differ in several respects in their interaction with water. Pine heartwood showed (i) lower liquid uptake, (ii) lower swelling, (iii) higher contact angle, and (iv) lower level of dissolution of surface active components (extractives) than pine sapwood. We conclude that the method is also suitable for studying wetting properties of other porous and swellable materials. The wettability results were supported by surface chemical analysis using X-ray photoelectron spectroscopy, showing higher extractives and lignin content on heartwood than on sapwood surfaces.

  • 153.
    Sedighi Moghaddam, Maziar
    et al.
    SP Tech Res Inst Sweden, S-11486 Stockholm, Sweden.
    Claesson, Per M.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Yt- och korrosionsvetenskap.
    Wålinder, Magnus E. P.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial.
    Swerin, Agne
    KTH, Skolan för kemivetenskap (CHE), Kemi, Yt- och korrosionsvetenskap.
    Wettability and liquid sorption of wood investigated by Wilhelmy plate method2014Ingår i: Wood Science and Technology, ISSN 0043-7719, E-ISSN 1432-5225, Vol. 48, nr 1, s. 161-176Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The wettability of Scots pine veneers was investigated with different approaches using the Wilhelmy plate method. The probe liquids were water and octane, which differ; in that, water is able to swell the wood sample, whereas octane does not. Novel approaches based on the Wilhelmy plate method to study wettability, liquid penetration, and swelling behavior of wood veneers are introduced. First, immersion to constant depth was performed, and liquid uptake with time was evaluated. Different kinetic regimes, the fastest one associated with contact angle changes and the slowest regime associated with liquid sorption by capillary and diffusion, were observed. Two other approaches, imbibition at constant depth (with initial deeper immersion) and full immersion, were utilized in order to keep the contact angle constant during measurements. Dynamic wettability studies were done by a multi-cycle (10-20 cycles) Wilhelmy method. Based on this, the time-dependent swelling of wood and changes in sample perimeter could be obtained. Generally, water showed higher absorption than octane. In all wettability studies, and for both probe liquids, the penetration process starts with a fast initial sorption, which is followed by swelling in the case of water.

  • 154.
    Sedighi Moghaddam, Maziar
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Yt- och korrosionsvetenskap. SP Technical Research Institute of Sweden.
    Heydarihamedani, Golrokh
    KTH, Skolan för kemivetenskap (CHE), Kemi, Yt- och korrosionsvetenskap.
    Tuominen, Mikko
    SP Technical Research Institute of Sweden.
    Fielden, Matthew
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Nanostrukturfysik.
    Haapanen, Janne
    TUT Tampere University of Technology, Aerosol Physics Laboratory, Department of Physics.
    Mäkelä, Jyrki M.
    TUT Tampere University of Technology, Aerosol Physics Laboratory, Department of Physics.
    Wålinder, E.P. Magnus
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial.
    Claessson, M. Per
    KTH, Skolan för kemivetenskap (CHE), Kemi, Yt- och korrosionsvetenskap.
    Swerin, Agne
    KTH, Skolan för kemivetenskap (CHE), Kemi, Yt- och korrosionsvetenskap. SP Technical Research Institute of Sweden.
    Hydrophobisation of wood surfaces by combining liquid flame spray (LFS)and plasma treatment: dynamic wetting properties2016Ingår i: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, Vol. 70, nr 6, s. 527-537Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The hydrophilic nature of wood surfaces is a major cause for water uptake and subsequent biological degradation and dimensional changes. In the present paper, a thin transparent superhydrophobic layer on pine veneer surfaces has been created for controlling surface wettability and water repellency. This effect was achieved by means of the liquid flame spray (LFS) technique, in the course of which nanoparticulate titanium dioxide (TiO2) was brought to the surface, followed by plasma polymerisation. Plasma polymerised perfluorohexane (PFH) or hexamethyldisiloxane (HMDSO) were then deposited onto the LFS-treated wood surfaces. The same treatment systems were applied to silicon wafers so as to have well-defined reference surfaces. The dynamic wettability was studied by the multicycle Wilhelmy plate method, resulting in advancing and receding contact angles as well as sorption behaviour of the samples during repeated wetting cycles in water. Atomic force microscopy (AFM) and Xray photoelectron spectroscopy (XPS) were employed to characterise the topography and surface chemical compositions and to elucidate the question how the morphology of the nanoparticles and plasma affect the wetting behaviour. A multi-scale roughness (micro-nano roughness) was found and this enhanced the forced wetting durability via a superhydrophobic effect on the surface, which was stable even after repeated wetting cycles. The hydrophobic effect of this approach was higher compared to that of plasma modified surfaces with their micro-scale modification.

  • 155.
    Sedighi Moghaddam, Maziar
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Yt- och korrosionsvetenskap. SP Technical Research Institute of Sweden.
    Van den Bulcke, Jan
    Wålinder, E.P. Magnus
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial.
    Calessson, M. Per
    KTH, Skolan för kemivetenskap (CHE), Kemi, Yt- och korrosionsvetenskap.
    Van Acker, Joris
    Swerin, Agne
    KTH, Skolan för kemivetenskap (CHE), Kemi, Yt- och korrosionsvetenskap. SP Technical Research Institute of Sweden.
    Microstructure of chemically modified wood using X-ray computedtomography scanning in relation to wetting propertiesManuskript (preprint) (Övrigt vetenskapligt)
    Abstract [en]

    X-ray computed tomography was utilized to visualize and quantify the 2D and 3D microstructure of acetylated and furfurylated southern yellow pine (SYP) and maple samples. The total porosity and the porosity of different anatomical components, the cell wall thickness and the maximum opening of tracheid lumens were evaluated. The wetting properties (swelling and capillary uptake) were related to these microstructural characteristics. Our data show significant changes in the wood structure for furfurylated sapwood samples, including a change in tracheid shape and filling of tracheids by furan polymer. In contrast, no such changes were noted for acetylated samples at the resolution of the measurement (0.8 μm). The images obtained for furfurylated maple samples demonstrated that all ray cells and some vessel elements were filled with furan polymer while the fibres largely remained unchanged. Furfurylation significantly decreased the porosity of the sample, and this was observed in both earlywood and latewood regions in southern yellow pine softwood samples. In contrast, the total porosity of this softwood sample was hardly affected by acetylation. These findings are in line with wetting results demonstrating that furfurylation reduces both swelling and capillary uptake in contrast to acetylation which reduces mostly swelling. Cell wall thickness measurements revealed a significant increase after chemical modification especially at higher levels of furfurylation.

  • 156.
    Sedighi Moghaddam, Maziar
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial. SP Tech Res Inst Sweden Chem Mat & Surfaces, Sweden.
    Van den Bulcke, Jan
    Wålinder, Magnus E. P.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial.
    Claesson, Per M.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Yt- och korrosionsvetenskap.
    Van Acker, Joris
    Swerin, Agne
    KTH, Skolan för kemivetenskap (CHE), Kemi, Yt- och korrosionsvetenskap.
    Microstructure of chemically modified wood using X-ray computed tomography in relation to wetting properties2017Ingår i: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, Vol. 71, nr 2, s. 119-128Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    X-ray computed tomography (XCT) was utilized to visualize and quantify the 2D and 3D microstructure of acetylated southern yellow pine (pine) and maple, as well as furfurylated pine samples. The total porosity and the porosity of different cell types, as well as cell wall thickness and maximum opening of tracheid lumens were evaluated. The wetting properties (swelling and capillary uptake) were related to these microstructural characteristics. The data show significant changes in the wood structure for furfurylated pine sapwood samples, including a change in tracheid shape and filling of tracheids by furan polymer. In contrast, no such changes were noted for the acetylated pine samples at the high resolution of 0.8 mu m. The XCT images obtained for the furfurylated maple samples demonstrated that all ray cells and some vessel elements were filled with furan polymer while the fibers largely remained unchanged. Furfurylation significantly decreased the total porosity of both the maple and pine samples. Furthermore, this was observed in both earlywood (EW) and latewood (LW) regions in the pine samples. In contrast, the total porosity of pine samples was hardly affected by acetylation. These findings are in line with wetting results demonstrating that furfurylation reduces both swelling and capillary uptake in contrast to acetylation which reduces mostly swelling. Furfurylation significantly increased the cell wall thickness of both the maple and pine samples, especially at higher levels of furfurylation.

  • 157.
    Sedighi Moghaddam, Maziar
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Yt- och korrosionsvetenskap. SP Technical Research Institute of Sweden.
    Wålinder, E.P. Magnus
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial.
    Calessson, M. Per
    KTH, Skolan för kemivetenskap (CHE), Kemi, Yt- och korrosionsvetenskap.
    Swerin, Agne
    KTH, Skolan för kemivetenskap (CHE), Kemi, Yt- och korrosionsvetenskap. SP Technical Research Institute of Sweden.
    Wettability and swelling of acetylated and furfurylated wood analyzed by multicycle Wilhelmy plate method2016Ingår i: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, Vol. 70, nr 1, s. 69-77Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The wetting, dimensional stability and sorption properties of a range of modified wood samples obtained either by acetylation or furfurylation were compared with those of unmodified samples of the same wood species via a multicycle Wilhelmy plate method. Wettability measurements were performed with water and octane as the swelling and non-swelling liquids, respectively. It was found that acetylation reduces water uptake mainly by reducing the swelling. In comparison, furfurylation reduces both swelling and the void volume in the sample. To quantify the effect of the modification process of the wood properties, the parameters “liquid up-take reduction” and the “perimeter change reduction” were introduced, which were determined from multicycle Wilhelmy plate measurements. Compared with the acetylated wood, the furfurylated wood with a higher level of weight percent gain exhibited larger property changes on the surface and in terms of swelling and sorption properties.

  • 158.
    Segerholm, B. Kristoffer
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial.
    Vellekoop, Stefan
    Wålinder, Magnus E. P.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial.
    Process-related mechanical degradation of the wood component in high-wood-content wood-plastic composites2012Ingår i: Wood and Fiber Science, ISSN 0735-6161, Vol. 44, nr 2, s. 145-154Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Micromorphological studies of wood plastic composites (WPC) are crucial for deeper understanding of their physical, mechanical, and durability properties. The objective of this study was to examine process-related mechanical degradation of the wood component in an extruded high-wood-content WPC. WPC with approximate to 70% wood content and three distinctly different ground wood components were manufactured by a conical extrusion technology, ie WPC were prepared with an unmodified, acetylated, or thermally modified wood component. Size and shape of wood components were determined before and after the extrusion process. Micromorphology of WPC samples was studied using a scanning electron microscope (SEM) and a surface preparation technique based on UV laser ablation. This micromachining technique was also applied to prepare that specimens for micromechanical analysis using a tensile stage mounted in a SEM. Results show that extrusion processes cause a significant mechanical degradation of the wood component. Degradation was most pronounced for the thermally modified wood component, and interestingly, this resulted in a more homogenous WPC micromorphology compared with WPC with unmodified and acetylated wood components. WPC with thermally modified wood also exhibited the highest micromechanical strength.

  • 159.
    Segerholm, Kristoffer
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial.
    Characteristics of wood plastic composites based on modified wood: Moisture properties, biological performance and micromorphology2012Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Biobased materials made from renewable resources, such as wood, play an important role in the sustainable development of society. One main challenge of biobased building materials is their inherent moisture sensitivity, a major cause for fungal decay, mold growth and dimensional instability, resulting in decreased service life as well as costly maintenance. A new building material known as wood-plastic composites (WPCs) has emerged. WPCs are a combination of a thermoplastic matrix and a wood component, the former is usually recycled polyethylene or polypropylene, and the latter a wood processing residual, e.g. sawdust and wood shavings.

    The objective of this thesis was to gain more insight about characteristics of WPCs containing a modified wood component. The hypothesis was that a modified wood component in WPCs would increase the moisture resistance and durability in outdoor applications. The study comprises both injection molded and extruded WPC samples made with an unmodified, acetylated, thermally modified or furfurylated wood component in a polypropylene (PP), high density polyethylene (HDPE), cellulose ester (CAP, a cellulose ester containing both acetate and propionate substituents) or polylactate (PLA) matrix. The WPCs were prepared with 50-70 weight-% wood. The emphasis was on studying the moisture sorption, fungal resistance and micromorphological features of these new types of composites. Water sorption in both liquid and vapor phases was studied, and the biological performance was studied both in laboratory and in long term outdoor field tests. Micromorphological features were assessed by analyzing of the wood component prior to and after processing, and by studying the composite microstructure by means of a new sample preparation technique based on UV excimer laser ablation combined with scanning electron microscopy (SEM).

    Results showed that the WPCs with a modified wood component had a distinctly lower hygroscopicity than the WPCs with unmodified wood, which resulted in less wood-plastic interfacial cracks when subjected to a moisture soaking-drying cycle. Durability assessments in field and marine tests showed that WPCs with PP or CAP as a matrix and 70 weight-% unmodified wood degraded severely within a few years, whereas the corresponding WPCs with a modified wood component were sound after 7 years in field tests and 6 years in marine tests. Accelerated durability tests of WPCs with PLA as a matrix showed only low mass losses due to decay. However, strength losses due to moisture sorption suggest that the compatibility between the PLA and the different wood components must be improved. The micromorphological studies showed that WPC processing distinctly reduces the size and changes the shape of the wood component. The change was most pronounced in the thermally modified wood component which became significantly reduced in size. The disintegration of the modified wood components during processing also creates a more homogeneous micromorphology of the WPCs, which may be beneficial from a mechanical performance perspective. Future studies are suggested to include analyses of the surface composition, the surface energy and the surface energy heterogeneity of both wood and polymer components in order to tailor new compatible wood-polymer combinations in WPCs and biocomposites.

  • 160.
    Segerholm, Kristoffer
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial.
    Ibach, Rebecca E
    Moisture and Fungal Durability of Wood-Plastic Composites Made With Chemically Modified and Treated Wood Flour2013Ingår i: Proceedings IRG Annual Meeting, 2013, s. IRG/WP 13-40648-Konferensbidrag (Refereegranskat)
    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.

  • 161.
    Segerholm, Kristoffer
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial.
    Ibach, Rebecca E.
    Westin, Mats
    Durability of PLA - Modified Wood Composites2011Ingår i: Proceedings of the 11th International Conference on Wood & Biofiber Plastic Composites, 2011Konferensbidrag (Refereegranskat)
  • 162.
    Segerholm, Kristoffer
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial.
    Ibach, Rebecca E.
    Westin, Mats
    Moisture sorption, biological durability, and mechanical performance of WPC containing modified wood and polylactates2012Ingår i: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 7, nr 4, s. 4575-4585Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Biological durability is an important feature for wood-plastic composites (WPC) intended for outdoor applications. One route to achieving WPC products with increased biological durability is to use wood preservative agents in the formulation of the WPC. Another option could be to use a chemically modified wood component that already exhibits increased resistance to biological degradation. There is also a need to use biobased thermoplastics made from renewable resources, which would decrease the dependency on petrochemically-produced thermoplastics in the future. The objective of this study was to examine moisture sorption properties, biological durability, and mechanical performance of injection-molded WPC samples based on acetylated or thermally modified wood components and a polylactate matrix. The biological durability was evaluated in a terrestrial microcosm (TMC) test according to ENV 807, followed by mechanical evaluation in a center point bending test. The moisture sorption properties were investigated via both water soaking and exposure in a high-humidity climate. Low or negligible mass losses were observed in the TMC test for all WPC samples. However, the mechanical evaluation after exposure in the TMC test showed 35-40% losses in both strength and stiffness for the WPC containing an unmodified wood component.

  • 163.
    Segerholm, Kristoffer
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial.
    Ibach, Rebecca E.
    Wålinder, Magnus
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial.
    Moisture sorption in artificially aged wood-plastic composites2012Ingår i: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 7, nr 1, s. 1283-1293Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Moisture sorption in wood-plastic composites (WPCs) affects their durability and dimensional stability. In certain outdoor exposures, the moisture properties of WPCs are altered due to e. g. cracks induced by swelling and shrinkage of the components, as well as UV degradation or biological attack. The aim of this work was to study the effect of different artificial ageing routes on the moisture sorption properties of WPCs. Extruded WPCs were prepared with either unmodified or acetylated wood and recycled high-density polyethylene (HDPE). The WPC samples were artificially aged involving water soaking, artificial weathering, and white-or brown-rot decay in different combinations. After the ageing, the samples were conditioned in either 65% or 90% relative humidity (RH) until equilibrium moisture content was reached. A dynamic moisture sorption analyzer was used to monitor the sorption rate of samples subjected to a climate change from 65% to 90% RH. Scanning electron microscopy was used to study the surface morphology of the aged composites. Results showed that the artificial weathering caused cracking of the HDPE matrix at the composite surface, as well as a wood-matrix debonding, resulting in an increased moisture sorption rate. The WPC samples subjected to white-rot decay showed the highest moisture sorption rate.

  • 164.
    Segerholm, Kristoffer
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial.
    Larsson Brelid, Pia
    Wålinder, Magnus
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial.
    Westin, Mats
    Frisk, Olof
    Biological outdoor durability of WPC with chemically modified wood2012Ingår i: Proceedings of the 6th European conference on wood modification / [ed] Jones, D., Militz, H., Petrič, M., Pohleven, F., Humar, M. and Pavlič, M., 2012, s. 47-54Konferensbidrag (Refereegranskat)
  • 165.
    Segerholm, Kristoffer
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial.
    Omidvar, Asghar
    Wålinder, Magnus
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial.
    Acetylation to Minimize Water Uptake and Deformation of High Wood Content WPC2009Ingår i: The Fourth European Conference on Wood Modification, 2009, s. 239-242Konferensbidrag (Refereegranskat)
  • 166.
    Segerholm, Kristoffer
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial.
    Rowell, Roger M.
    Larsson Brelid, Pia
    Wålinder, Magnus
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial.
    Westin, Mats
    Söderström, Ove
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial.
    Micromorphology and Durability of WPCs made from Chemically Modified Wood2007Ingår i: Proceedings of the 3rd meeting of the Nordic Baltic Network in Wood Material Science and Engineering, 2007Konferensbidrag (Refereegranskat)
  • 167.
    Segerholm, Kristoffer
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial.
    Rowell, Roger Max
    Larsson Brelid, Pia
    Wålinder, Magnus E.P.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial.
    Westin, Mats
    Alfredsen, G.
    Improved Durability and Moisture Sorption Characteristics of Extruded WPCs made from Chemically Modified Wood2007Ingår i: Proceedings of the 9th International Conference on Wood & Biofiber Plastic Composites., 2007, s. 251-256Konferensbidrag (Refereegranskat)
  • 168.
    Segerholm, Kristoffer
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial.
    Walkenström, Pernilla
    IFP Research, Swedish Institute for Fibre and Polymer Research.
    Nyström, B.
    SICOMP, Swedish Institute of Composites.
    Wålinder, Magnus
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial.
    Larsson Brelid, Pia
    SP Trätek, Technical Research Institute of Sweden.
    Micromorphology, moisture sorption and mechanical properties of a biocomposite based on acetylated wood particles and cellulose ester2007Ingår i: Wood Material Science and Engineering, ISSN 1748-0272, Vol. 3-4, nr 2, s. 106-117Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    One of the major issues in a long-term perspective for the use of wood-plastic composites (WPCs) in outdoor applications is the moisture sensitivity of the wood component and the consequent dimensional instability and susceptibility to biological degradation of the composite. In this work, the effects of using an acetylated wood component and a cellulose ester as matrix on the micromorphology, mechanical performance and moisture uptake of injection-moulded WPCs have been studied. Composites based on unmodified and acetylated wood particles, specially designed with a length-to-width ratio of about 5-7, combined with both cellulose acetate propionate (CAP) and polypropylene (PP) matrices were studied. The size and shape of the wood particles were studied before and after the processing using light microscopy, and the micromorphology of the composites was studied using a newly developed surface preparation technique based on ultraviolet laser irradiation combined with low-vacuum scanning electron microscopy (LV-SEM). The water vapour sorption in the composites and the effect of accelerated weathering were measured using thin samples which were allowed to reach equilibrium moisture content (EMC). The length-to-diameter ratio was only slightly decreased for the acetylated particles after compounding and injection moulding, although both the unmodified and the acetylated particles were smaller in size after the processing steps. The tensile strength was about 40% higher for the composite based on acetylated wood than for the composite with unmodified wood using either CAP or PP as matrix, whereas the notched impact strength of the composite based on acetylated wood was about 20% lower than those of the corresponding unmodified composites. The sorption experiments showed that the EMC was 50% lower in the composites with an acetylated wood component than in the composites with an unmodified wood component. The choice of matrix material strongly affected the moisture absorptivity of the WPC. The composites with CAP as matrix gained moisture more rapidly than the composites with PP as matrix. It was also found that accelerated ageing in a Weather-Ometer® significantly increased the moisture sensitivity of the PP-based composites.

  • 169.
    Segerholm, Kristoffer
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial.
    Westin, Mats
    Larsson Brelid, Pia
    Wålinder, Magnus
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial.
    Wood Plastic Composites from Modified Wood and CAP2009Ingår i: 4th Wood Fibre Polymer Composites International Symposium, 2009Konferensbidrag (Refereegranskat)
  • 170.
    Segerholm, Kristoffer
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial.
    Wålinder, Magnus
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial.
    Dimensional changes due to water sorption in high wood-content WPCs prepared with modified wood2010Ingår i: In Proceedings of the fifth European Conference on Wood Modification, ECWM5, 2010Konferensbidrag (Refereegranskat)
  • 171.
    Segerholm, Kristoffer
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial.
    Wålinder, Magnus
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial.
    Inverse gas chromatography characterization of wood composite components2012Ingår i: Proceedings of the 8th meeting of the Northern European Network for Wood Science and Engineering (WSE) / [ed] Baltrušatits, A. and Ukvalbergienė, K., 2012, s. 58-63Konferensbidrag (Refereegranskat)
  • 172.
    Segerholm, Kristoffer
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial.
    Wålinder, Magnus
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial.
    Bardage, Stig L.
    Mould growth resistance of fungicide-containing WPC2011Ingår i: Proceedings of the 7th meeting of the Nordic-Baltic Network in Wood Material Science & Engineering (WSE), 2011, s. 25-30Konferensbidrag (Refereegranskat)
  • 173.
    Segerholm, Kristoffer
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial.
    Wålinder, Magnus
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial.
    Holmberg, Daniel
    Adhesion studies of scots pine-polypropylene bond using ABES2010Ingår i: In Proceedings of the 6th meeting of the Nordic-Baltic Network in Wood Material Science and Engineering, WSE, 2010Konferensbidrag (Refereegranskat)
  • 174.
    Segerholm, Kristoffer
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial.
    Wålinder, Magnus
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial.
    Larsson Brelid, Pia
    Walkenström, Pernilla
    Westin, Mats
    Wood plastic composites made from acetylated wood: Effects on water vapour sorption behaviour and durability2005Ingår i: Proceedings of the 9th European Panel Products Symposium, 2005, s. 233-242Konferensbidrag (Refereegranskat)
  • 175.
    Sidorova, Ekaterina
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial.
    Morén, Tom
    Luleå tekniska universitet.
    The Behaviour of Heat Treated Wooden Cladding Exposed to Extreme Climate Changes2010Ingår i: Proceedings of the 6th meeting of the Nordic-Baltic Network In Wood Material Science And Engineering (WSE) / [ed] Pille Meier, 2010, s. 147-154Konferensbidrag (Refereegranskat)
    Abstract [en]

    The heat treated (HT) ThermoD and oil heat treated (OHT) samples were prepared for the test. ThermoD samples were prepared by treating wood with superheated steam and saturated steam. Oil heat treated samples were heat treated in oil under 180ºC and cooled directly in clean oil at the room temperature. During cooling the samples absorbed some oil. Untreated samples of pine, spruce and aspen were prepared as the reference samples.The material was tested for 5 cycles. Each cycle contained: soaking in water for 24 hours, direct freezing for 6 days and direct warming for 30 minutes. The tested species were pine, spruce and aspen. Water absorption depended on type of species and treatment. Pine had higher water absorption but after oil heat treatment had the lowest water absorption due to high oil contain. Spruce and aspen had approximately the same water absorption. Heat treatment reduced water absorption as it was expected. Samples degraded in colour more or less and some started to crack. Almost all untreated and ThermoD treated pine samples cracked. Spruce had the highest visible change of the colour after the test. Aspen showed the best results because the colour did not change significantly and the material did not crack. Oil heat treated samples of pine lost some oil after the test

  • 176.
    Sidorova, Ekaterina
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial.
    Trey, Stacy
    SP Sveriges Tekniska Forskningsinstitut.
    Englund, Finn
    SP Sveriges Tekniska Forskningsinstitut.
    Modification of wood with an anti-oxidant tannin derivative: preliminary study2011Ingår i: Proceedings of the 7th meeting of the Nordic-Baltic Network in Wood Material Science & Engineering (WSE) 2011, 2011, s. 161-166Konferensbidrag (Refereegranskat)
  • 177.
    Sjökvist, T.
    et al.
    Linnaeus Univ, Dept Forestry & Wood Technol, SE-35195 Vaxjo, Sweden..
    Wålinder, Magnus E.P.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial.
    Blom, A.
    Linnaeus Univ, Dept Forestry & Wood Technol, SE-35195 Vaxjo, Sweden..
    Liquid sorption characterisation of Norway spruce heartwood and sapwood using a muiticycle Wilhelmy plate method2018Ingår i: International Wood Products Journal, ISSN 2042-6445, E-ISSN 2042-6453, Vol. 9, nr 2, s. 58-65Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A multicycle Wilhelmy plate method was applied to study the water and octane sorption behaviour of small Norway spruce veneers. Dry heart- and sapwood samples of varying density were investigated. The results showed a correlation between the porosity and the sorption of octane for all samples, i.e. a higher wood porosity resulted in higher octane sorption. However, no difference in octane sorption was found between heart- and sapwood samples of similar density. The water sorption behaviour was difficult to interpret, probably due to the influence of surface-active wood extractives. It is suggested that the presence of such extractives, particularly in the sapwood samples, increases the sorption of water due to a significant decrease in its apparent surface tension. Hence, the results indicate that the liquid water sorption of spruce heart- and sapwood is strongly influenced by variations in the extractives content rather than by the micromorphology.

  • 178.
    Sjölund, Magdalena
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial.
    Stenis, Nelly
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial.
    Limträhybrider av acetyleradbjörk och obehandlad gran: En experimentell och numerisk analys av vissamekaniska egenskaper och fuktbeteende2019Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    I Sverige finns en lång tradition kring användandet av trä för konstruktionsändamål. I den storskaligabyggindustrin har det dock kommit att handla mycket om stål och betong och detta gäller inteminst för konstruktioner utomhus såsom broar. I träkonstruktioner har speciellt infästningarna storbetydelse då dessa är svåra att skydda från fukt, vilket gör att träets begränsande beständighetblir en anledning att välja andra material. Genom kemisk modifiering av trä, så kallad acetylering,kan detta beständighetsproblem lösas, dock med risk för kraftigt ökade materialkostnader. Syftetmed detta arbete var att undersöka möjligheterna kring så kallade limträhybrider av kemiskt modifieradbjörk och omodifierad gran. Tanken är att erhålla god beständighet i svårskyddade delarav en limträbalk, t.ex. vid knytpunkter, utan att behöva använda modifierat trä i hela balken.Genom att fingerskarva samman de två materialen kan det acetylerade materialet användas justintill infästningen och sedan övergå till obehandlat trä i områden som lättare kan skyddas från riskför röta med hjälp av till exempel konstruktionstekniskt träskydd. Mer specifikt handlar arbetetom att studera hur en sådan typ av hybridkonstruktion beter sig när den testas i fyrpunktsböjning.Speciellt undersöktes hur och var brottet uppkom samt balkarnas böjhållfasthet och styvhet.Dessutom undersöktes, med hjälp av småskaliga tester, hur acetyleringen av björk påverkar dessE-modul och hållfasthet.Studien är baserad på både experimentella försök och numerisk analys. Fyrpunktsböjning användesvid försök på hybridbalkarna och materialtesterna. Finita elementmetoder användes för attförutspå var brott kommer att uppstå samt hur området vid fingerskarvarna påverkas av den storaskillnaden i svällningsegenskaper mellan obehandlat trä och det mer dimensionsstabila modifieradeträet.Resultaten indikerade att den acetylerade björken hade större spridning med avseende på det undersöktamaterialegenskaperna jämfört med omodifierad björk. Testerna av hybridbalkarna visadepå stora problem kring fingerskarvarna beroende på problem vid limningen och även lokala defekter.Resultaten visade även en klar förbättring gällande balkarnas styvhet då limträbalkarnasmittpartier bestod av björk.Även de finita elementberäkningarna indikerade att brott kan förväntas i fingerskarvarna samtatt problem kan uppstå som följd av att limträet av omodifierad gran sväller vid uppfuktning ijämförelse med limträet av acetylerad björk. Vidare forskning föreslås bland annat kring utvecklingav lim som lämpar sig för såväl barr- som lövträ, obehandlat- som acetylerat material samtfingerskarvning. Resultaten av studien visar på goda utsikter att förbättra limträets styvhet ochböjhållfasthet samt en möjlighet till att lösa problem med fukt kring infästningar.

  • 179.
    Sjöström, Christer
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial.
    Trinius, Wolfram
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap.
    North European Regional Platform: PeBBu Regional Platform 12005Rapport (Övrigt vetenskapligt)
  • 180.
    Sjöström, Christer
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial.
    Trinius, Wolfram
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap.
    Chevalier, Jean-Luc
    Life Performance of Construction Materials and Components: PeBBu Domain 1 Final Report2005Rapport (Övrigt vetenskapligt)
  • 181.
    Strömberg, Larissa
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial.
    Application of workshop technique to sustainable design2005Ingår i: the Proceedings of the SB05 Tokyo: Action for Sustainability - The 2005 World Sustainable Building Conference in Tokyo, Japan, 27 - 29 September 2005, 2005, s. 1157-1162Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    "Sustainability" is only one of the many new definitions in the coating industry over last decade, but one, which has the greatest potential to affect change. To achieve sustainable development we must consider all kind of coatings impact into the environment, including environmental economic and social load. This kind of conceptual thinking can be applied at any level and for any decision-making process. The workshop method, developed in this study, expedites the selection of coating during conceptual design by developing a set of expressions that relate coating technical performance indicators (colour change, flaking, etc.) to environmental and economic impacts. These performance-based relationships provide a common ground for choosing among similarly functioning coating systems and provide insight for minimizing the environmental burdens. This paper has also described the process of testing a workshop technique for involving stakeholders and decision makers in generating "sustainable design" for exterior wood coatings. In this sense, the workshop method developed in this study is a tool in this process. One important element in the process of policy formulation in any workshop method is procedural justice, which is based on the multiple criteria analysis here.

  • 182.
    Strömberg, Larissa
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial.
    Paulsen, Jacob
    Schaller, Christian
    A method for choosing sustainable exterior wood coatings in the design phase2005Ingår i: Surface Coatings International Part B - Coatings Transactions, ISSN 1476-4865, E-ISSN 1742-0261Artikel i tidskrift (Övrigt vetenskapligt)
  • 183.
    Söderström, Ove
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial.
    Dynamic Capillary Transport of Water in Porous Building Materials2005Ingår i: Nordic Symposium on Building Physics, 2005Konferensbidrag (Refereegranskat)
  • 184.
    Söderström, Ove
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial.
    Mathematics for PhD-students in Building Science2007Samlingsverk (redaktörskap) (Refereegranskat)
  • 185.
    Tapparo, Alessandra
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial.
    Engineered wood glass combination: Innovative glazing façade system2017Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    Buildings require a lot of energy during all their lifetime, from the construction site to the use and demolition. The building sector contributes to a large part of the total emissions of greenhouse gases and consume a large amount of water and energy resources, so the material components used in the building sector have gained an important role in the discourse of sustainability. The tendency is to use natural renewable materials that generates lower environmental impact than conventional ones and are able to fulfil the required structural and architectural needs.

    Wood is a traditional material with a long and proud history and has been reintroduced in the construction site thanks to its sustainable characteristics. Wood used for building applications, i.e. timber, is capable to capture CO2 from the atmosphere and incorporate so-called carbon storage. Moreover, low process energy requirements and high recyclability increase the potential of timber to become a major building material. On the other hand, the considerable growing demand for highly transparent envelopes has recently resulted in massive introduction of glass as a façade component. The main objective of this thesis was therefore to elaborate on the question if it is possible to merge the positive aspects of these two materials.

    The thesis starts with a discussion on hybrid, composite and combined materials. The key concept is to merge two or more materials with different characteristics, which result in a finished product with better overall properties than the starting constituents. However, such building material systems are not well categorized and a new term is therefore introduced to describe the combination between wood and glass: engineered wood glass combination (EWGC).

    The product is then described presenting the characteristics and properties of wood and glass and the structural benefits of the whole panel. The EWGC product possesses some advantageous properties like transparency, stiffness and strength for glass and the ductile nature of timber when used under compression. Moreover, this wood-glass element enables load transfer of horizontal forces through the glass pane so that the additional metal bracing elements for stiffening the building can be omitted.

    Then the study goes deeper in the architectural possibilities and different potential types of assembly are described. However, only few profiles have been tested and this has resulted in the market production of only one type of panel that is currently used in the construction site. Moreover, the shape of the EWGC is suitable to integrate systems that can control the ventilation rate and solar gains, allowing the development of advanced integrated façades that ensure the comfort condition inside the building.

    EWGC is also seen to be highly potential as an ecological alternative to conventional structural sealant aluminium-glass façade. For this reason, the life cycle assessment (LCA) of different materials is discussed in order to evaluate their environmental impacts. LCA results are strongly dependent on the calculation boundaries and the choice of database, but it stands out that aluminium, as a construction material for glazing elements, requires up to 4 times higher primary energy demand and produces up to 16 times more CO2 emission than timber based combined panels. Despite some weak points, e.g. the lack of standardized regulations and people’s preconceptions about wood, the overall conclusion is that EWGC has the potential to be used for future building envelopes of multi-storey timber buildings.

  • 186.
    Tebaldi, G.
    et al.
    Italy.
    Apeagyei, A.
    United Kingdom.
    Elaguine, Denis
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial. KTH, Skolan för teknikvetenskap (SCI), Hållfasthetslära (Inst.), Hållfasthetslära (Avd.).
    Falchetto, A. C.
    Germany.
    Advanced measurement systems for crack characterization2018Ingår i: Mechanisms of Cracking and Debonding in Asphalt and Composite Pavements, Springer, 2018, s. 155-227Kapitel i bok, del av antologi (Refereegranskat)
    Abstract [en]

    The previous chapters describe numerical models and testing methods designed to simulate, to repeat and to understand the cracking phenomena in asphalt materials and asphalt pavement (or pavements with at least one asphalt layer). This chapter shows some of the most advanced systems to measure the parameters related to cracking. They are classified using a classification grid that considers the most relevant characteristics of the measurement system. The proposed classification method was designed to provide a quick understanding of what data the systems are able to provide and what they can analyze.

  • 187.
    Tjernberg, Frida
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial.
    Wind-induced dynamic response of a 22-storey timber building: Options for structural design of the Hallonbergen project2015Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    Folkhem is a Swedish company exclusively building timber residential buildings in the Stockholm area. The company is currently in the planning stages of what would be the world’s tallest timber building, a 22-storey timber residential buiding in Hallonbergen, Sundbyberg. In this master thesis, this proposed building has been analyzed with regards to its wind-induced dynamic response. The work includes studies of stabilization of tall structures, case studies of existing buildings and developed systems for tall timber construction and analyzed options for structural design of the Hallonbergen project. Eleven different structural systems have been investigated with regards to their displacement at the top and their peak acceleration when subject to wind loading. The peak acceleration has been calculated using both Eurocode and ISO 4354. The values have been assessed against ISO 6897 and ISO 10137. The results indicate that it is possible to construct the Hallonbergen project without risk of unacceptable dynamic response, using any of the following options;

    • The Martinson’s system with 259 mm CLT plates
    • The Kauffmann system
    • The structural system presented in “The Case for Tall Wood Buildings”
    • The structural system presented in “The Timber Tower Research Project”
  • 188. Toller, S.
    et al.
    Larsson, Magnus
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial.
    Implementation of life cycle thinking in planning and procurement at the swedish transport administration2017Ingår i: Pavement Life-Cycle Assessment - Proceedings of the Pavement Life-cycle Assessment Symposium, 2017, CRC Press/Balkema , 2017, s. 281-287Konferensbidrag (Refereegranskat)
    Abstract [en]

    According to transport policy objectives, limiting the energy use and climate impact of the transport system, including infrastructure, is an important task for the Swedish Transport Administration (STA). Choices that affect climate performance of transport infrastructure are made at different stages in the planning process. The STA has developed the Klimatkalkyl climate calculation model for an efficient, consistent life cycle calculation of infrastructure greenhouse gas emissions and energy use. As a result of the model’s implementation in planning and procurement, a life cycle perspective is now being used on a regular basis for environmental procurement claims, decision support and monitoring purposes. 

  • 189.
    Twumasi Afriyie, Ebenezer
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial.
    Karami, Peyman
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Norberg, Peter
    Högskolan i Gävle.
    Gudmundsson, Kjartan
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsteknik.
    Textural and thermal conductivity properties of a low density mesoporous silica material2014Ingår i: Energy and Buildings, ISSN 0378-7788, E-ISSN 1872-6178, Vol. 75, s. 210-215Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this study, the pore structure, tapped density and thermal conductivity properties of a new type of nanoporous silica material have been studied. We have applied nitrogen physisorption, high resolution scanning microscopy and Transient Plane Source thermal conductivity measurements to investigate these properties. The new mesoporous silica SNP have large BET surface area, 400-439 m2 g-1 and possess high porosity in the range of 95-97%. The results further show pore diameter centred at 43 nm or 47 nm for the two materials studied. Tapped densities as low as 0.077 g/cm3 have so far been obtained and the thermal conductivity of these materials has been measured to 0.0284 and 0.0294 W (m K)-1 at room temperature and atmospheric pressure. The effects of tapped density, pore size diameter and particle morphology on thermal conductivity are discussed.

  • 190.
    Twumasi Afriyie, Ebenezer
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial.
    Norberg, Peter
    Högskolan i Gävle.
    Sjöström, Christer
    Högskolan i Gävle.
    Forslund, Mikael
    Högskolan i Gävle.
    Textural and hydrogen sulphide adsorption behaviour of double metal-silica modified with potassium permanganate2013Ingår i: Journal of porous materials, ISSN 1380-2224, E-ISSN 1573-4854, Vol. 20, nr 3, s. 447-455Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A new MgCa-silica material with bimodal pore size is impregnated with KMnO4 for dynamic adsorption of H2S. The MgCa-silica was synthesized using sodium silicate and calcium and magnesium salts as precipitating agents. The KMnO4 impregnation onto MgCa-silica was obtained through either direct addition into MgCa-silica wet coagulum or doping of dried MgCa-silica pellets into KMnO4 solution. These chemisorbents were characterized by nitrogen physisorption, spectrophotometer, microscopy and dynamic H2S adsorption test setup similar to ASHRAE standard I45.I. The results show that impregnation route and KMnO4 wt% cause a reduction of surface area and total pore volume. The decrease in pore volume was slightly more in chemisorbents obtained via post doping compared to direct impregnation. Regardless of pore volume reduction the pore size range, 1-32 nm, was as in the parent MgCa-silica with micro and meso-pore diameter centered at 1.4 and 5.4 nm respectively. Thus obtained chemisorbents have their pore entrances neither blocked nor shifted. The MgCa-silica/KMnO4 chemisorbents exhibits good H2S uptake performance. The chemisorbent with 11.4 wt% KMnO4 and obtained via direct impregnation possesses the highest uptake capacity. The lowest capacity was observed for chemisorbent with 8 wt% KMnO4 and made by direct impregnation. The variations in uptake capacity are likely due to impregnation route, the KMnO4 content and its location in the pore system. The results suggest that the MgCa-silica/KMnO4 chemisorbents can remove H2S from indoor air at room temperature.

  • 191.
    Twumasi, Ebenezer
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial.
    Molecular filtration: the study of adsorbents2011Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Adsorbent materials for gas purification have been studied and developed for application in many areas. It is known that a single adsorbent may not adequately control multiple contaminants. Therefore, the development of adsorbent materials has accelerated over the past two decades, and is today an area attracting a lot of attention. In view of the global environmental movement for clean air, the development of improved sorbents will help address new challenges that cannot efficiently be met with the generic sorbents that are presently commercially available. On the other hand, the utilization of these new sorbents for specific applications within the area of molecular filtration remains largely unexplored. This thesis presents a synthesis of new sorbent materials, and the characterization and application of these materials for molecular filtration. Commercial adsorbents have been used for benchmarking for the pore properties, the applicability, and the performance of these new adsorbents. A double metal-silica adsorbent has been synthesized. The preparation procedure is based on the use of sodium silicate coagulated with various ratios of magnesium and calcium salts which yields micro-meso porous structures in the resulting material. The results show that molar ratios of Mg/Ca influence the pore parameters as well as the structure and morphology. The bimodal pore size can be tailored by controlling the Mg/Ca ratio. The effect of thermal treatment on pore parameters of these adsorbents has been investigated. The results show that heat treatment had a notable effect on the pore parameters, and that the pore structure was thermally stable even at 600°C.

     A synthesis method has also been developed for the preparation of carbon-silica composites. The method involves a number of routes, which can be summarised as addition of activated carbon particles to (I) the paste, (II) the salt solution, or (III) with the sodium silicate solution. In route II and III the activated carbon is present also before coagulation. The routes presented here leads to carbon-silica composites possessing high micro porosity, meso porosity as well as large surface areas. The increase in micro porosity and surface areas was linear with carbon content. The results shows further that pore size distribution may be tailored based on the route of addition of the carbon particles. Following route I and III a wide pore size (1-30nm) was obtained where as by route II a narrow pore size (1-4nm) was observed. KOH or KMnO4 modified MgCa adsorbent varieties were also prepared. The impregnationwas performed by either a direct synthesis or post-synthesis procedure. Potassium hydroxide and potassium permanganate have been chosen as impregnate chemicals. Results revealed that theimpregnate amount significantly affected both the structural and the gas adsorption characteristics of the impregnated MgCa adsorbents. The properties of double- metal adsorbents, impregnated adsorbents and carbon-silica composites were characterized by various methods (X-ray diffraction, scanning electron microscopy, thermo gravimetric analysis, and nitrogen adsorption at 77K) to study the material structure and morphology, thermal stability, ignition temperature and porous parameters with regard to surface area, pore size, pore size distribution and porosity volume, which is important for optimizing their use in many practical application. The up-take performance of adsorbents for dynamic adsorption of SO2, H2S and toluene was performed in a system similar to the setup usedin ASHRAE 145.1. Finally the applicability and performance of the impregnated modified MgCa-silica adsorbents and composites have been evaluated for H2S, SO2 and toluene adsorption and compared to some commercial adsorbent materials. Results revealed that a potassium permanganate modified MgCa-adsorbent has a H2S adsorption capacity in the range of 0.08-3.19 wt % at 50% efficiency, and that the uptake capacity was relative to the amount of potassiumpermanganate loading. Moreover, KOH modified MgCa-adsorbent shows highest SO2 adsorption capacity (1.7 wt %) which is 3.47 times higher than commercial alumina impregnate with potassium permanganate (0.49 wt %). Carbon-silica composites on the other hand shows adsorption of toluene and high adsorption capacity was obtained when carbon content was 45 wt %. The results further shows that a composite with 45 wt % carbon and obtained via route I present the highest toluene adsorption capacity ( 27.6 wt % relative to carbon content) at 0% efficiency. The large uptake capacity of this composite was attributed to the presence of high microporosity volume and a wide (1-30nm) bimodal pore system consisting of extensive mesopore channels (2-30nm) as well as large surface area. These capacity values of carbon-silica composites are competitive to results obtained for commercial coconut based carbon (31 wt %), and better than commercial alumina-carbon composite.

  • 192.
    Twumasi, Ebenezer
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial.
    Forslund, Mikael
    Högskolan i Gävle.
    Norberg, Peter
    Högskolan i Gävle.
    Sjöström, Christer
    Högskolan i Gävle.
    Textural and adsorption properties of a carbon-silica composite adsorbent for air filtration2010Ingår i: World journal of Engineering, ISSN 1708-5284, Vol. 7, nr 2, s. 227-228Artikel i tidskrift (Övrigt vetenskapligt)
  • 193.
    Twumasi, Ebenezer
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial.
    Norberg, Peter
    Högskolan i Gävle.
    Sjöström, Christer
    Högskolan i Gävle.
    Forslund, Mikael
    Högskolan i Gävle.
    Effects of heat treatment and impregnation on the textural properties and H2S uptake of a new precipitated silica adsorbentIngår i: Adsorption, ISSN 0929-5607, E-ISSN 1572-8757Artikel i tidskrift (Övrigt vetenskapligt)
  • 194.
    Twumasi, Ebenezer
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial.
    Norberg, Peter
    Högskolan i Gävle.
    Sjöström, Christer
    Högskolan i Gävle.
    Forslund, Mikael
    Högskolan i Gävle.
    Preparation and characterization of double metal-silica sorbent for gas filtration2013Ingår i: Adsorption, ISSN 0929-5607, E-ISSN 1572-8757, Vol. 19, nr 1, s. 49-61Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This paper presents the preparation of a porous (Mg, Ca) silicate structure, which could be employed as sorbent filter media. The sorbents have been prepared using sodium silicate precipitated with various ratios of magnesium and calcium salts. The sorbents obtained were characterized using scanning electron microscope (SEM), X-ray diffraction (XRD) and nitrogen physisorption isotherm. Further, the applicability and performance of the sorbent impregnate with potassium hydroxide for removal of sulphur dioxide (SO2) has been demonstrated. From the isotherms, specific surface area, pore diameter and volume of pores were estimated. Results show that the chemical composition and textural properties of the resultant sorbents were highly dependent on Mg/Ca molar ratio. It was found that sorbents made with 68 mol% Mg and 32 mol% Ca (PSS-MgCa-68/32); and 75 mol% Mg and 25 mol% Ca (PSS-MgCa-75/25) exhibited even higher specific surface area and pore volume than the sorbents containing a single metal. The Mg/Ca-silica sorbents obtained contains interconnected bimodal porosity with large portions being mesopores of varied sizes. The pore size distribution (PSD) results further indicate that PSS-MgCa-68/32 sorbent exhibits wide PSD of interconnected pores in the size range of 1 to 32 nm while PSS-MgCa-50/50 and PSS-MgCa-75/25 exhibits narrow PSD of 1 to 5 nm. Using SO2 as model contaminate gas, it was shown that the dynamic adsorption performance of the PSS-MgCa-sorbents impregnated with 8 wt% KOH exhibits SO2 uptake, with impregnated PSS-MgCa-68/32 showing better performance. This shows that the materials prepared can be used as adsorbent for gas filtration.

  • 195. Uetimane, Ernesto, Jr.
    et al.
    Allegretti, Ottaviano
    Terziev, Nasko
    Söderström, Ove
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial.
    Application of non-symmetrical drying tests for assessment of drying behaviour of ntholo (Pseudolachnostylis maprounaefolia PAX)2010Ingår i: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, Vol. 64, nr 3, s. 363-368Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Experiments concerning drying behaviour of ntholo (Pseudolachnostylis maprounaefolia PAX) were conducted to find a suitable drying schedule. Two non-symmetrical drying (NSD) tests were carried out to determine the drying behaviour of ntholo in terms of drying rate and stress behaviour. A tentative drying schedule was selected for comparison of the test results with those of similar tests with other known species. The schedule was tested in a laboratory kiln on 28-mm thick boards. According to both NSD tests and laboratory tests, ntholo dries easily but slowly. The laboratory drying lasted 266 h and achieved standard drying quality characterised by 8.9% moisture content, a moisture gradient of 1.2% and a case-hardening (gap) of 1.2 mm. Twist was the largest deformation with 3.4 mm per 1000 mm on average. The assigned schedule provided standard drying quality and it could be tested further in industrial kilns.

  • 196. Vahtikari, Katja
    et al.
    Rautkari, Lauri
    Noponen, Tuula
    Lillqvist (nee Laine), Kristiina
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial.
    Hughes, Mark
    The influence of extractives on the sorption characteristics of Scots pine (Pinus sylvestris L.)2017Ingår i: Journal of Materials Science, ISSN 0022-2461, E-ISSN 1573-4803, Vol. 52, nr 18, s. 10840-10852Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The sorption behaviour of extracted and un-extracted Scots pine (Pinus sylvestris L.) heartwood was analysed using dynamic vapour sorption apparatus. In addition to the sorption isotherm and hysteresis, the moisture increments and decrements were determined as well as the rate of sorption. Parallel exponential kinetics model was used for further analysis. The effect of cyclic humidity loading on the sorption characteristics was studied by exposing samples to ten repeated sorption cycles and by determining the amount of accessible hydroxyl (OH) groups before and after the cyclic humidity loading. Removal of extractives led to an increase in EMC both in adsorption and in desorption. Hysteresis decreased due to the removal of extractives. Cyclic humidity loading reduced the sorptive capacity of wood material for both extracted and un-extracted wood, but was more pronounced in un-extracted wood. However, despite the decrease in the sorptive capacity, the amount of accessible OH groups increased after ten repeated dry-humid cycles.

  • 197.
    Vieira, Tiago
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial. VTI.
    Tyre-road Interaction: a holistic approach to noise and rolling resistance2018Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [sv]

    Energiförluster, bränsleförbrukning, fastighetspriser och hälsoproblem är några av de effekter som följer av däckens interaktion med vägytan och som relaterar till de funktionella egenskaperna för rullmotstånd och buller. De första två effekterna uppkommer av väg- och däckinteraktionen eftersom energi förbrukas mestadels genom hysteresförluster när däcken utsätts för dynamiska deformationer vid kontakt med vägytan. Den andra effekten av däck/vägkontakten som analyseras i avhandlingen är buller. Alltför hög bullerexponering intill boendemiljöer leder till minskning av fastighetspriser och även till hälsoproblem såsom ökat blodtryck, sömnstörning, kognitiv försämring hos barn, med mera.

    För att mildra sådana problem, är det avgörande att ha en god förståelse av de bakomliggande orsakerna, och därför används här ett helhetsgrepp för att genomföra en mer omfattande analys av interaktionen. Analysen inkluderar egenskaper hos vägytan, däcken, omgivande miljö samt kontaktmedier (förorenande skikt).. Både buller och rullmotstånd har analyserats efter att på ett kontrollerat sätt ha varierat en viss variabel medan de andra variablerna hållits konstanta, och sedan jämföra resultaten med referensförhållandet. I den första delen av denna undersökning provades flera olika däck medan vägytan, miljö- och kontaktmedier hölls konstanta. Detta möjliggjorde en utvärdering av effekterna av olika vinterdäck på rullmotstånd och buller. I den andra delen beskrivs effekter av en förändring av vägytan, utförd genom att slipa bort topparna i vägtexturen, medan de andra variablerna hålls konstanta..

    Den första delen kvantifierar bullerökningen vid användning av dubbdäck i jämförelse med odubbade vinterdäck. Några betydande skillnader i rullmotstånd hittades däremot inte mellan de två däckgrupperna. Den andra delen av texten visar på potentialen av horisontell slipning för att minska buller och rullmotstånd, dock är varaktigheten begränsad; särskilt för svenska vägar där dubbdäck används.

  • 198.
    Vieira, Tiago
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial. VTI.
    Sandberg, Ulf
    VTI.
    Acoustical performance of winter tyres on two in-service road surfaces: a frequency spectrum analysis and comparison2017Ingår i: Proceedings of the Inter-Noise 2017, Hong Kong, 2017, s. 6825-6836Konferensbidrag (Refereegranskat)
  • 199.
    Vieira, Tiago
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial. VTI.
    Sandberg, Ulf
    VTI.
    Negative Texture, Positive for the Environment: Results of Horizontal Grinding of Asphalt Pavements2018Konferensbidrag (Refereegranskat)
    Abstract [en]

    A pavement surface having its texture deflections mostly directed downwards is said to have a “negative texture” and is expected to result in positive tire/road noise and rolling resistance properties. Negative textures are typical of porous asphalt pavements, but another way to achieve this is to grind-off the top of the asperities of a rough-textured surface. This paper explores the application of grinding pavement texture by tools operating in the horizontal plane (not to be confused with common “diamond grinding” which is made by tools operating in the vertical plane) on a number of asphalt pavements in Sweden, including porous asphalt and stone matrix asphalt. Noise measurements with the Close Proximity method were carried out to evaluate the different acoustical performance of the ground and the original surfaces. In most cases, also tire/road rolling resistance was measured. Texture and wet friction measurements were carried out to characterize how the grinding operation changed the surface texture. It was demonstrated that the grinding treatment led to a more negatively skewed surface texture, resulting in an A-weighted noise reduction up to 3 dB, while rolling resistance coefficients were reduced by up to 15 %. It is concluded that horizontal grinding indeed creates more “negative textures”, which results in improved noise and rolling resistance properties without sacrificing friction, though with limited longevity.

  • 200.
    Vieira, Tiago
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial. VTI.
    Sandberg, Ulf
    VTI.
    Erlingsson, Sigurdur
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap. VTI.
    Acoustical performance of winter tyres on in-service road surfaces2019Ingår i: Applied Acoustics, ISSN 0003-682X, E-ISSN 1872-910X, Vol. 153, s. 30-47Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Exposure to excessively high noise levels is a relevant health problem in Europe and road traffic noise is the most widespread noise source. When considering cold climate countries, the available scientific literature on noise emission properties of winter tyres is still very limited. In order to contribute into filling this knowledge gap, this paper investigates the acoustical performance of different types of tyres, with focus on winter tyres, on different road surfaces, at different speeds, and with different states of wear. The results indicate that studded winter tyres have, indeed, an increased noise level at frequencies between 315 Hz and 10 kHz, having a significantly different response especially at frequencies higher than 4 kHz. The acoustical response also depends on the tyre type when comparing different road surfaces, as a result of conflicting vibrational and aerodynamic noise generation mechanisms. Additionally, the relationship between labelled and measured values was explored, however, no statistically significant relationship was found between them (and labelling is not applied for studded tyres). A frequency spectrum correction was attempted based on previous measurements on an ISO track, which reduced the difference between measured and labelled values, however, further investigation is still required to properly understand differences between label and road measurements, where the label is determined on a test track with a special, smooth surface.

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