Endre søk
Begrens søket
45678910 301 - 350 of 710
RefereraExporteraLink til resultatlisten
Permanent link
Referera
Referensformat
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annet format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annet språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf
Treff pr side
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sortering
  • Standard (Relevans)
  • Forfatter A-Ø
  • Forfatter Ø-A
  • Tittel A-Ø
  • Tittel Ø-A
  • Type publikasjon A-Ø
  • Type publikasjon Ø-A
  • Eldste først
  • Nyeste først
  • Skapad (Eldste først)
  • Skapad (Nyeste først)
  • Senast uppdaterad (Eldste først)
  • Senast uppdaterad (Nyeste først)
  • Disputationsdatum (tidligste først)
  • Disputationsdatum (siste først)
  • Standard (Relevans)
  • Forfatter A-Ø
  • Forfatter Ø-A
  • Tittel A-Ø
  • Tittel Ø-A
  • Type publikasjon A-Ø
  • Type publikasjon Ø-A
  • Eldste først
  • Nyeste først
  • Skapad (Eldste først)
  • Skapad (Nyeste først)
  • Senast uppdaterad (Eldste først)
  • Senast uppdaterad (Nyeste først)
  • Disputationsdatum (tidligste først)
  • Disputationsdatum (siste først)
Merk
Maxantalet träffar du kan exportera från sökgränssnittet är 250. Vid större uttag använd dig av utsökningar.
  • 301.
    Johansson, Jimmy
    Växjö universitet, Fakulteten för matematik/naturvetenskap/teknik, Institutionen för teknik och design.
    Mechanical processing for improved products made from Swedish hardwood2008Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Swedish hardwood is today used in the energy, pulp and mechanical hardwood industries. Only very small volumes of Swedish hardwood are, however, consumed by the mechanical industry that normally pays the highest timber price. The smallness of the volumes used for mechanical refinement is a result both of forestry not focusing on the production of hardwood for these uses, and of the fact that the mechanical hardwood industry, particularly the sawing industry, is not designed to process the existing raw material in an optimal manner. This thesis discusses the possibilities of improving the conditions for the mechanical refinement of hardwood. The aim of the work has been to investigate the possibilities of developing products and methods for processing of Swedish hardwood.

    The thesis proposes a new manufacturing system for Swedish hardwood to better utilize the inherent properties of the wood material. The system is based on the so-called PrimWood Method and the star-sawing concept. Compared to normally sawn wood, the sawing concept utilizes the raw material more efficiently with regard to volume yield, and increases the distance between knots in the sawn wood. The material produced has vertical annual rings which give the wood smaller movements as a result of moisture variations and a different textural appearance. Using the PrimWood Method for hardwood would make it possible to more closely match customer requirements regarding hardwood products.

    Since Swedish hardwood is nowadays mainly used indoors, a possible way of expanding the market would be to increase the outdoor use of the material. Here the durability is of great importance, and one important factor is then the capillary characteristics of the material. The thesis therefore focuses on the characterisation of the capillarity in wood for the future improvement of its durability. It is shown that with the material produced by the proposed manufacturing system, i.e. wood with vertical annual rings, the possibility of using hardwood outdoors increases, because the susceptibility to cracking decreases.

  • 302.
    Johansson, Jimmy
    Högskolan i Kalmar, Institutionen för teknik.
    The Swedish hardwood sawmill industry: Structure present status and development potential2008Inngår i: Wood Material Science & Engineering, ISSN 1748-0272, E-ISSN 1748-0280, Vol. 3, nr 3/4, s. 94-101Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This study describes the Swedish hardwood sawmill industry with respect to its structure, raw material, production and market conditions in order to seek ways of increasing the competitiveness of the industry. Fifteen sawmills were studied through observations and interviews. The Swedish hardwood sawmill industry creates job opportunities in sparsely populated areas and uses a biological raw material which is important for environmental biological diversity. Any decrease in the use of this material will mean a drop in the incentive for forest owners to cultivate deciduous forests. Today, the hardwood sawmill industry is experiencing problems in securing the supply of raw material of the desired quality, i.e. without knots and discoloured heartwood (red-heart or brown-heart). To increase the competitiveness of the Swedish hardwood sawmill industry, the raw material supply must be secured. Production should be geared towards products demanded by the market, and new markets need to be entered.

  • 303.
    Johansson, Jimmy
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Blomqvist, Lars
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggteknik (BY).
    Nilson, Henrietta
    Linnéuniversitetet, Ekonomihögskolan (FEH), Institutionen för organisation och entreprenörskap (OE).
    Landscheidt, Steffen
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Influencing factors to enable automation of wood furniture production2016Inngår i: Proceedings of the 12th meeting of the Northern European Networkfor Wood Science and Engineering (WSE): Wood science andengineering – a key factor on the transition to Bioeconomy / [ed] Bruno Andersons and Arnis Kokorevics, Riga, Latvia: Latvian State Institute of Wood Chemistry , 2016, s. 208-213Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The wood furniture industry in Sweden has an identified need of technological development in order to stay competitive. Especially the necessity to focus on automation has been identified. In the industry there are often needs to handle large levels of customization at the same time as keeping the production effective. This requires flexible automation solutions, often described as automated equipment that can rapidly be reconfigured for new products.Before automated applications are implemented in an industry there are issues to solve related to organisational, human and technological aspects. Based on this, the project - Flexible automation in manufacturing of laminated veneer products was initiated. The project is running since January 1, 2016 and is a two year national Swedish project. The aim of the project is to investigate challenges concerning automation in the wood furniture industry and especially focusing on bended laminated veneer products.In the project a case-study with the aim of identifying factors important for successful automation implementation in an involved wood manufacturing industry was performed. Key persons and staff of the company were asked to tell their life stories and a process mapping of the production was conducted.The results indicate a problematic relation between the management and the production staff, which partly can be referred to the shift from a family business to a private owned firm. Based on the process mapping, internal transport and handling are identified improvement areas. Productivity is disturbed by stops caused by processing residues and poorly defined materials. There is potential for improvement by adapting a process-oriented approach and defining the materials used.The case–study confirms the need to consider organizational and human aspects in production before initiating production. The study concludes the need to consider the special aspects of the wood material in production development.

  • 304.
    Johansson, Jimmy
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Blomqvist, Lars
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Sandberg, Dick
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Challenges using dielectric heating for THM processing of solid wood2013Inngår i: Evaluation, processing and predicting of THM treated wood behaviour by experimental and numerical methods / [ed] Carmen-Mihaela Popescu and Maria-Cristina Popescu, Iasi, Romania, 2013, s. 55-56Konferansepaper (Fagfellevurdert)
  • 305.
    Johansson, Jimmy
    et al.
    Linnéuniversitetet, Fakultetsnämnden för naturvetenskap och teknik, Institutionen för teknik, TEK.
    Salin, Jarl-Gunnar
    Application of percolation modelling on end-grain water absorption in aspen (Populus tremula L.)2011Inngår i: Wood Material Science & Engineering, ISSN 1748-0272, E-ISSN 1748-0280, Vol. 6, nr 3, s. 112-118Artikkel i tidsskrift (Fagfellevurdert)
  • 306.
    Johansson, Jimmy
    et al.
    Linnéuniversitetet, Fakultetsnämnden för naturvetenskap och teknik, Institutionen för teknik, TEK.
    Sandberg, Dick
    Linnéuniversitetet, Fakultetsnämnden för naturvetenskap och teknik, Institutionen för teknik, TEK.
    Automatic sorting of sawn birch: Defect detection possibilities on sawn and planed wood surfaces2010Inngår i: Hardwood research and utilisation in Europe: New Challanges / [ed] Robert Nemeth and Alfred Teischinger, Sopron: University of West Hungary Press , 2010, s. 206-213Konferansepaper (Fagfellevurdert)
    Abstract [en]

    In the production of sawn hardwood a critical processing step is the quality grading. The grading has normally been handled manually in the hardwood sawmills. The process has been labour intensive and a problematic working environment. With the help from existing scanning technology it is possible to automate the process with several benefits as a result. These are e.g. a decreased need of labour, a better working environment and the possibility to use more complicated grading rules. Thereby the wood could be used in a more optimal way with both cost and environmental benefits.

    One problem when grading hardwood is that camera and laser based scanning technology has mainly been used on planed surfaces. Normally the quality grading in hardwood sawmills is performed before planing. The wood may then be cross-cutted to components before planing in order to minimise the volume losses because of deformations of the wood pieces.

    In order to investigate the possibilities to scan the sawn wood before planing rip-sawn birch boards (Betula pubescens Ehrh., Betula pendula Roth.) was scanned before and after planing the wood. The used scanner was a commercial system for automatic sorting of wood. Before the scanning it was estimated that the sawn surfaces exposed to the surrounding environment during drying would not generate any usable results from the scanning. Therefore only the two rip-sawn surfaces were used for evaluation before and after planing. The evaluation was made by comparing the results from the quality grading before and after the planing based on grading rules used by Swedish hardwood sawmill. The results show that there are possibilities to grade the birch wood before planing. The study, however, shows that the scanner has difficulties in detecting small colour variations as brown streaks and fresh knots. It is also difficult to detect fibre angle deviations because of loose fibres on the sawn surface. The possibilities to scan the birch wood are thereby related to the grading rules, i.e. if the mentioned quality parameters are allowed or not.

  • 307.
    Johansson, Jimmy
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Sandberg, Dick
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT). Luleå University of Technology.
    Integrated use of product data for improved wood material utilization in the furniture and joinery production2013Inngår i: Pro Ligno, ISSN 1841-4737, E-ISSN 2069-7430, Vol. 9, nr 4, s. 321-327Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Quality communication from customer to supplier is crucial for the effectiveness of a value chain. In the forest products industry, a mutual understanding of quality requirements between customer and supplier in relation to material characteristics and production conditions is important if the material is to be utilized effectively.

     

    In the mechanical wood industry, hardwood has normally been quality graded manually. This has been a work-intensive operation and a problematic working environment. Automatic grading equipment based mainly on camera and laser technology is therefore gradually replacing the manual grading operation which relies on the human eye. The cross-cutting of sawn wood into shorter components with well-defined quality parameters is a process which needs to be automated. This makes it possible for the sawmill to redefine the quality grading process with e.g. more complex grading rules. To gain full benefits from the new technology, however, the grading process must be redefined in cooperation with the customers. There is also an expressed need for tools to communicate the quality of products produced by sawmills.

     

    In this study, three case studies were therefore performed where the communication of requirements between sawmills and customers was studied with regard to three different components delivered from two sawmills. In one sawmill, two products were studied; one intended for a furniture producer and one for a joinery producer. In the other sawmill, the studied product was intended for a producer of solid wood panels. The idea has been to study the need for product information expressed by both the customer and supplier through the automatic grading process and to utilise this equipment for data collection and visualisation.

     

    The requirements for a communication and data exchange tool have been derived. There is often an expressed need to measure how different raw materials affect the volume yield in a process and how different quality requirements affect the volume yield. Sharing this information between customer and supplier has been shown to yield a mutual understanding of how and why deviations occur. Visualisation possibilities are a prerequisite for a mutual understanding of quality conceptions.

  • 308.
    Johansson, Jimmy
    et al.
    Växjö universitet, Fakulteten för matematik/naturvetenskap/teknik, Institutionen för teknik och design.
    Sandberg, Dick
    Linnéuniversitetet, Fakultetsnämnden för naturvetenskap och teknik, Institutionen för teknik, TEK.
    Ny träteknik höjer värdet på lövskogen2008Inngår i: Ekbladet, ISSN 0283-4839, nr 23, s. 24-27Artikkel i tidsskrift (Annet vitenskapelig)
    Abstract [sv]

    Lövträ är ett uppskattat material i möbler, snickerier och inredningar samtidigt som en stor del av det svenska lövträet av olika anledningar inte utnyttjas för dessa användningsområden. Endast ca. 5 % av den totala volymen lövträ som årligen avverkas blir sågat virke. Motsvarande siffra för furu och gran är 50 %. Istället importeras den största delen av råvaran, men bakom knuten väntar nya spännande nyheter, vilka är ett  resultat av forskningen vid Växjö universitets avdelning för Skog & Trä.

  • 309.
    Johansson, Jimmy
    et al.
    Växjö universitet, Fakulteten för matematik/naturvetenskap/teknik, Institutionen för teknik och design.
    Sandberg, Dick
    Växjö universitet, Fakulteten för matematik/naturvetenskap/teknik, Institutionen för teknik och design.
    Preparation of wood with pulsed UV-laser ablation for characterisation of the wood structure2007Inngår i: Proceedings of Third International Symposium on Wood Machining, Presses polytechniques et universitaires romandes , 2007, s. 191-194Konferansepaper (Fagfellevurdert)
    Abstract [en]

    In contrast to mechanical techniques involving cutting with a knife, cutting with a microtome or grinding, pulsed UV-laser ablation is an irradiation technique where a so-called Excimer laser is used, and the process is adiabatic, which means that no or a very little chemical change occurs in the material being processed. Cross sections of samples of Scots pine and Norway spruce which had been exposed outdoors have been prepared with the help of an Excimer laser (wavelength 248 nm) for study in a microscope. UV-laser ablation has been found to be a suitable method of preparation for wood when it is desired to obtain thin sections with little influence on the material, and particularly when dealing with brittle materials, e.g. archaeological wood, biologically-attacked wood or, as in this case, wood which has been exposed outdoors.

  • 310.
    Johansson, Jimmy
    et al.
    Växjö universitet, Fakulteten för matematik/naturvetenskap/teknik, Institutionen för teknik och design.
    Sandberg, Dick
    Växjö universitet, Fakulteten för matematik/naturvetenskap/teknik, Institutionen för teknik och design.
    The Concept of Value Activation II.: The PrimWood Method for improved properties of hardwood products.2005Inngår i: Hardwood research and utilisation in Europe: new challanges / [ed] Bejo, L., Sopron: University of West Hungary , 2005, s. 53-59Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The name Value activation refers to the basic understanding of wood, where at present there are properties that are not fully exploited, but with help of a new sawing pattern could be fully utilized. The basic idea lies at an industrial level producing radial sawn timber with good profitability and with lesser and mostly a controllable moisture movement. In short it implies an activation of values of timber that has not been exploited in ordinary industrial production to date.

    This paper gives one example how the basic ideas in the concept of Value activation can be implemented in the industry. A new manufacturing system, the PrimWood Method, producing radial sawn timber, well adjusted to the conditions of the Swedish hardwood sawmill industry is presented. The manufacturing system generates knot and defect-free hardwood products with vertical annual rings.

    Utilizing the proposed manufacturing system in the Swedish hardwood sawmill industry imply an increased focus on hardwood in consumer products, which gain both forestry, sawmill industry and the wood manufacturing industry.

  • 311.
    Johansson, Jimmy
    et al.
    Linnéuniversitetet, Fakultetsnämnden för naturvetenskap och teknik, Institutionen för teknik, TEK.
    Sandberg, Dick
    Linnéuniversitetet, Fakultetsnämnden för naturvetenskap och teknik, Institutionen för teknik, TEK.
    Volymutbyte vid tillverkning av kvistfria snickeriämnen och skivor med stående årsringar2005Rapport (Annet vitenskapelig)
    Abstract [sv]

    Denna rapport beskriver ett nytt produktionskoncept för tillverkning av högkvalitativa träkomponenter och skivor av massivt trä från barr- och lövträ. Konceptet, som benämns PrimWood-metoden, resulterar i ett kvistfritt virke med stående årsringar. Det sågade virket har antingen ett rektangulärt eller ett triangulärt tvärsnitt och benämns Rektangel respektive Trekant. Dessa två virkesformer vidareförädlas till ämnen, komponenter och skivor.

    PrimWood-metoden medför både en betydande kvalitetshöjning jämfört med virke framtaget med konventionella metoder (hårdare yta, formstabilare material, sprickfri yta, enklare och snabbare bearbetning, mindre spill samt en jämnare ytbehandling) och nyvunna estetiska egenskaper (t.ex. jämn textur, kvistfria ytor, dekorativa fingerskarvar). PrimWood-metoden förbättrar också råvaruutbytet, vilket är positivt ur miljöhänseende på grund av att ett högre utnyttjande erhålls av en förnyelsebar råvara.

    Volymutbytet vid framtagning av de olika produkter som PrimWood-metoden resulterar i har studerats ingående, både teoretiskt och experimentellt under industriella förhållanden. För furu kan volymutbyten i olika förädlingssteg sammanfattas som:

    Sågning, från stock till torkat och justerat virke 56 %

    Kvistfria ämnen från Rektangel 75 %

    Kvistfria skivor från Rektangel (Panel) 52 %

    Kvistfria ämnen från Trekant (Romb) 73 %

    Kvistfria skivor från Trekant (Prisma) 53 %

    Volymutbytet för ämnen och skivor är här beräknat med avseende på ingående volym sågad och torkad Rektangel respektive Trekant. Råvarans kvalitet och geometriska form är naturligtvis avgörande för vilka volymutbyten som kan erhållas för processen. De ovan angivna volymutbytena får alltså endast ses som riktvärden vid förädling av svensk furu.

  • 312.
    Johansson, Jimmy
    et al.
    Växjö universitet, Fakulteten för matematik/naturvetenskap/teknik, Institutionen för teknik och design.
    Sandberg, Dick
    Växjö universitet, Fakulteten för matematik/naturvetenskap/teknik, Institutionen för teknik och design.
    Gustafsson, Åsa
    Växjö universitet, Fakulteten för matematik/naturvetenskap/teknik, Institutionen för teknik och design.
    Design of form stable and visually crack free edge-glued oak panels.2005Inngår i: Hardwood research and utilisation in Europe: new challanges / [ed] Bejo, L., Sopron: University of West Hungary , 2005, s. 167-171Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Edge-glued panels are a very appreciated material, for instance used in cabinet doors or worktops in the kitchen. The surrounding climate for these products is often severe, due to large seasonal variation of the relative humidity in the indoor air. Therefore problems regarding crack formation and form stability often occurs. This paper studies how annual ring orientation of lamellas, lamella width, initial different moisture content in the panels and single lamellas with deviating moisture content are affecting form stability and crack formation of edge-glued oak panels (Quercus robur).

    In the study 47 test samples with different characteristics were tested in varying climate during 182 days. The relative humidity was changed approximately every 14 days in the interval 18 to 88 % and temperature 20˚C. The panels were measured each 7 days regarding form stability factors. The crack formation was measured at the beginning and the end of the test.

    The evaluation of the results show that the annual ring orientation of the lamellas will be a significant factor regarding the form stability factors width changes and cupping of the panels and also regarding the crack formation. The lamella width is important as a significant factor regarding the surface evenness. Moisture content (initial level) will affect both the form stability and the crack formation. The effect of this factor is dependent on the relation to the climate of the surroundings.

  • 313.
    Johansson, Jimmy
    et al.
    Växjö universitet, Fakulteten för matematik/naturvetenskap/teknik, Institutionen för teknik och design.
    Sandberg, Dick
    Växjö universitet, Fakulteten för matematik/naturvetenskap/teknik, Institutionen för teknik och design.
    Gustafsson, Åsa
    Växjö universitet, Fakulteten för matematik/naturvetenskap/teknik, Institutionen för teknik och design.
    Secondary interior wood products for manufacturing in Swedish hardwood sawmills2005Inngår i: Hardwood research and utilisation in Europe: new challanges / [ed] Bejo, L., Sopron: University of West Hungary , 2005, s. 162-166Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The Swedish hardwood sawmill industry is today in a situation where the sawn hardwood exhibit a wide variation in quality characteristics, while the customers places strict demands. To create a profitable return for all their products the hardwood sawmill industry therefore must find new markets where other quality characteristics are valuable.

    In this study the requirements regarding logistic service and product quality characteristics for secondary wood products used as for instance indoor panelling and mouldings are identified and described. The industrial setting for the study is the Swedish retail and house building industry. The purpose of the study was to study the possibilities to increase the use of hardwoods in these products.

    The study follows a case study methodology. The studied companies consisted of in total nine companies in the southern part of Sweden. Six house-building companies were studied and three retail companies.

    A total of 15 different requirements regarding logistic service and product quality characteristics were identified. The product quality characteristics were related mainly to the aesthetic appearance of the products and to the stability of the product in service. The important logistical service requirements were related to the location and time of delivery and customer-specified orders.

    The results show that adjustment to customer requirements means that a supplier of hardwood products must adjust its organization towards a stronger customer focus. In order to do this a fundamental problem for Swedish hardwood sawmills is the current lack of an accepted quality sorting system for hardwood. It is also important for sawmills to control and adjust their production processes in order to gain increased flexibility and delivery precision.

    With the results from this study a test collection of mouldings and indoor panelling has been developed by a Swedish hardwood sawmill and is now tested by one of the retail companies within the study.

  • 314.
    Johansson, Jimmy
    et al.
    Växjö universitet, Fakulteten för matematik/naturvetenskap/teknik, Institutionen för teknik och design.
    Söderström, Ove
    Sandberg, Dick
    Växjö universitet, Fakulteten för matematik/naturvetenskap/teknik, Institutionen för teknik och design.
    Capillarity in hardwood: An important factor for hardwood market expansion2007Inngår i: The Beauty of Hardwood: Proceedings of third Conference on Hardwood Research and utilisation in Europe, University of West Hungary, Sopron , 2007Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The Swedish hardwood sawmills are today experiencing problems of finding profitable markets for products containing for instance knots and red or brown heartwood. By using hardwood outdoors, it would be possible to expand the market of hardwood with new products that may set other requirements on the wood than the present use. In Sweden today, hardwood is normally used in furniture, joinery, floors and kitchens where esthetical requirements are dominant. When considering outdoor use, technical requirements such as durability become more important and especially the capillary characteristics of the wood are of interest. The capillarity determines the ability of the material to absorb and desorb moisture, characteristics that affect the resistance of degrading. 

    In this paper, the capillary characteristics were modelled and studied by exposing the cross section of wood to a free water surface. The study compares two Swedish hardwood species, aspen and oak with pine, a softwood species that is common in Sweden and often used outdoors.

    The results show that the capillary transport mechanism is affected by the microstructure of the wood and the natural ability of the material to close the transport paths in the structure with for instance extractives, tyloses and closed pits. Based on these factors, a characteristic capillary mean radius is introduced to describe the longitudinal capillary water absorption in the studied wood species.

  • 315.
    Johansson, Jimmy
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Woxblom, Lotta
    Sveriges lantbruksuniversitet.
    Prerequisites for the Realization of the Transnational Communication Platform WoodApps.2013Inngår i: Proceeding of ISCHP2013 - International Scientific Conference on Hardwood Processing, October 7-9, Florence, Italy., 2013Konferansepaper (Annet vitenskapelig)
  • 316.
    Johansson, Marie
    et al.
    Växjö universitet, Fakulteten för matematik/naturvetenskap/teknik, Institutionen för teknik och design.
    Olsson, Anders
    Växjö universitet, Fakulteten för matematik/naturvetenskap/teknik, Institutionen för teknik och design.
    Grading of sawn timber with dynamic methods – influence of defects2009Inngår i: Proceedings of the COST E53 Workshop, Lisbon 22-23 October 2009 / [ed] José António Santos, 2009Konferansepaper (Annet vitenskapelig)
  • 317.
    Johansson, Marie
    et al.
    Växjö universitet, Fakulteten för matematik/naturvetenskap/teknik, Institutionen för teknik och design.
    Ormarsson, Sigurdur
    Technical University of Denmark.
    Influence of growth stresses and material properties on distortion of sawn timber – Numerical investigation.2009Inngår i: Annals of Forest Science, ISSN 1286-4560, E-ISSN 1297-966X, Vol. 66, nr 6, artikkel-id 604Artikkel i tidsskrift (Fagfellevurdert)
  • 318.
    Johansson, Martin
    Växjö universitet, Fakulteten för matematik/naturvetenskap/teknik, Institutionen för teknik och design.
    Hårdgörning av Asp2008Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
    Abstract [sv]

    Hårdgörning av trä syftar till att göra materialet hårdare. Detta går att åstadkomma genom komprimering, det komprimerade materialet tenderar dock att återgå mot sin ursprungsform då materialet utsätts för fukt om ingen låsning sker. Låsningen kan ske mekaniskt i en treskiktskonstruktion som motverkar träets fuktrörelser. Dessa skivor har dock visat sig vara instabila och tidigare försök har uppvisat deformationer i form av kupning. Denna undersökning syftar till att utreda förutsättningarna för att använda komprimerad asp samt att ta fram underlag för framtagning av en kommersiell produkt.

    Praktiska tester har genomförts för att studera hårdhet, återfjädring och densitet hos det komprimerade virket. Vidare har treskiktsskivor tagits fram för att testa om det går att få en stabil konstruktion genom att variera tjockleken på spärrskiktet. Även skillnader i acklimatiseringstid och fuktkvotens inverkan för virkets återfjädring har studerats.

    Resultaten visar på att aspens hårdhet efter komprimering blir i samma nivå som bok och ask, en låg fuktkkvot vid komprimering av materialet ger en låg återfjädring, komprimerat material har en längre acklimatiseringstid till jämviktsfuktkvot och materialet går att låsa tvärs fiberriktningen i en treskiktskonstruktion.

  • 319. Johnson, O.
    et al.
    Lindberg, Siv
    RISE., STFI-Packforsk.
    Roos, A.
    Hugosson, M.
    Lindström, Mikael
    RISE., STFI-Packforsk.
    Consumer perceptions and preferences on solid wood, wood-based panels, and composites: A repertory grid study2008Inngår i: Wood and Fiber Science, ISSN 0735-6161, Vol. 40, nr 4, s. 663-678Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Knowledge about consumer perception and preferences on solid wood, wood-based panels, and wood-based composites is important for product development and marketing. The aim of this study was to identify attributes and associations that people use to describe different types of wood materials and to explore how they relate to preferences. The study involved nine samples that were evaluated with the Kelly’s repertory grid technique and content analysis. Based on respondents’ answers, 19 core categories reflecting sample attributes were extracted. General preferences for each sample were also recorded. Principal component analysis generated two factors describing 1) naturalness, wood-likeness, softness, unprocessed origin, living, pleasant, and high value; and 2) solid and homogeneous impression. A third, preliminary factor included categories describing irregular pattern, sleekness, and smoothness. The wood samples were most liked, whereas composites and panels were not appreciated. Preferred core categories were naturalness, wood-likeness, smoothness, living impression, and value. The least liked core categories were processed, hard, and high weight. The implications of the results for product development and marketing are discussed. © 2008 by the Society of Wood Science and Technology.

  • 320.
    Josef, Füssl
    et al.
    Technische Univerität, Austria.
    Bader, Thomas K.Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggteknik (BY).Josef, EberhardsteinerTechnische Univerität, Austria.
    CompWood 2017 - Computational Methods in Wood Mechanics - From Material Properties to Timber Structures: Programme & Book of Abstracts2017Konferanseproceedings (Fagfellevurdert)
  • 321. Jäger, Andreas
    et al.
    Bader, Thomas K.
    Vienna University of Technology, Austria.
    Hofstetter, Karin
    Eberhardsteiner, Josef
    Identification of Elastic Properties of Wood Cell Walls by Means of Nanoindentation2009Inngår i: 26th Danubia-Adria Symposium on Advances in Experimental Mechanics, Leoben, Austria, 2009, s. 83-84Konferansepaper (Annet vitenskapelig)
  • 322.
    Jäger, Andreas
    et al.
    Vienna University of Technology, Austria.
    Bader, Thomas K.
    Vienna University of Technology, Austria.
    Hofstetter, Karin
    Vienna University of Technology, Austria.
    Eberhardsteiner, Josef
    Vienna University of Technology, Austria.
    The relation between indentation modulus, microfibril angle, and elastic properties of wood cell walls2011Inngår i: Composites. Part A, Applied science and manufacturing, ISSN 1359-835X, E-ISSN 1878-5840, Vol. 42, nr 6, s. 677-685Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Nanoindentation is a well known tool for identification of mechanical properties at the micrometer scale of materials. When applied to study wood cell walls the commonly used isotropic indentation theory is not applicable. In this study, anisotropic nanoindentation theory was employed for analyzing nanoindentation test results on wood cell walls. The influence of elastic stiffness components, microfibril angle, and cell wall composition on the indentation modulus was studied. The indentation modulus was found to depend on longitudinal, transverse, and shear modulus to a similar extent. A significant influence of the microfibril angle on the indentation modulus was observed and discussed with respect to experimental scatter and sample preparation. It is concluded, that application of anisotropic nanoindentation theory provides a tool for quantitative instead of qualitative investigation of wood cell walls, with the goal of identifying all elastic properties of the transversely isotropic cell wall from nanoindentation tests.

  • 323.
    Kallas, Åsa
    KTH, Skolan för bioteknologi (BIO), Träbioteknik.
    Heterologous expression, characterization and applications of carbohydrate active enzymes and binding modules2006Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Wood and wood products are of great economical and environmental importance, both in Sweden and globally. Biotechnology can be used both for achieving raw material of improved quality and for industrial processes such as biobleaching. Despite the enormous amount of carbon that is fixed as wood, the knowledge about the enzymes involved in the biosynthesis, re-organization and degradation of plant cell walls is relatively limited. In order to exploit enzymes more efficiently or to develop new biotechnological processes, it is crucial to gain a better understanding of the function and mechanism of the enzymes. This work has aimed to increase the knowledge about some of the enzymes putatively involved in the wood forming processes in Populus. Xyloglucan endotransglycosylases and a putative xylanase represent transglycosylating and hydrolytic enzymes, respectively. Carbohydrate binding modules represent non-catalytic modules, which bind to the substrate.

    Among 24 genes encoding for putative xyloglucan endotransglycosylases or xyloglucan endohydrolases that were identified in the Populus EST database, two were chosen for further studies (PttXTH16-34 and PttXTH16-35). The corresponding proteins, PttXET16-34 and PttXET16-35, were expressed in P. pastoris, purified and biochemically characterized. The importance of the N-glycans was investigated by comparing the recombinant wild-type proteins with their deglycosylated counterparts. In order to obtain the large amounts of PttXET16-34 that were needed for crystallization and development of biotechnological applications, the conditions for the large-scale production of PttXET16-34 in a fermenter were optimized.

    In microorganisms, endo-(1,4)-β-xylanases are important members of the xylan degrading machinery. These enzymes are also present in plants where they might fulfill a similar, but probably more restrictive function. One putative endo-(1,4)-β-xylanase, denoted PttXYN10A, was identified in the hybrid aspen EST library. Sequence analysis shows that this protein contains three putative carbohydrate-binding modules (CBM) from family 22 in addition to the catalytic module from GH10. Heterologous expression and reverse genetics were applied in order to elucidate the function of the catalytic module as well as the binding modules of PttXYN10A.

    Just as in microorganisms, some of the carbohydrate active enzymes from plants have one or more CBM attached to the catalytic module. So far, a very limited number of plant CBMs has been biochemically characterized. A detailed bio-informatic analysis of the CBM family 43 revealed interesting modularity patterns. In addition, one CBM43 (CBM43PttGH17_84) from a putative Populus b-(1,3)-glucanase was expressed in E. coli and shown to bind to laminarin (β-(1,3)-glucan), mixed-linked β-(1,3)(1,4)-glucans and crystalline cellulose. Due to their high specificity for different carbohydrates, CBMs can be used as probes for the analysis of plant materials. Generally, they are more specific than both staining techniques and carbohydrate-binding antibodies. We have used cellulose- and mannan binding modules from microorganisms as tools for the analysis of intact fibers as well as processed pulps.

  • 324.
    Karastergiou, Sotirios
    et al.
    Technological Educational Institute of Thessaly, Greece.
    Adamopoulos, Stergios
    Technological Educational Institute of Thessaly, Greece.
    Kakaras, Ioannis
    Technological Educational Institute of Thessaly, Greece.
    Voulgaridis, Elias
    Aristotle University of Thessaloniki, Greece.
    Passialis, Costas
    Aristotle University of Thessaloniki, Greece.
    Foti, Dafni
    Aristotle University of Thessaloniki, Greece.
    Koutsianitis, Dimitrios
    Aristotle University of Thessaloniki, Greece.
    Voulgaridou, Eleni
    Aristotle University of Thessaloniki, Greece.
    Blaskova, Genka
    University of Forestry, Bulgaria.
    Impregnation of fir (Abies borisii regis) and spruce (Picea excelsa) wood with rape oil and CCB preservative2014Inngår i: Wood Structure, Properties and Quality – 2014: 5th RCCWS International Symposium, Moscow State University Press, 2014, s. 77-82Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The objective of this study was to examine the retention (kg/m³) and the penetration depth (mm) as well as the impregnated area of cross sections (%) along the hole length, in fir (Abies borisii regis) and spruce (Picea excelsa) wood, after preservative treatment with rape oil and CCB preservative (3,2 %). The wood specimens (5×5 cm or 10×10cm in cross section and 40 cm long) with true radial and tangential surfaces, were treated with the full cell pro-cess. In order to determine the effect of direction (axial, lateral/radial or tangential) on pene-tration of rape oil and CCB preservative, the surfaces of the specimens were coated (laterally in all surfaces and in cross sections, respectively). Retention of rape oil ranged between 21,06 and 78,51 kg/m3 in fir specimens and between 11,20 and 90,32 kg/m3 in spruce specimens, while retention of CCB preservatives fluctuated between 1,68 and 10,05 kg/m3 in fir and be-tween 1,86 and 6,80 kg/m3 in spruce specimens. Penetration depth in all directions as well as impregnated area of cross sections of wood specimens were found to be lower in spruce than in fir for rape oil and, in most cases, for CCB preservative tested. The general conclusion is that both species are difficult to impregnation, but fir is more permeable than spruce.

  • 325.
    Karlsson, Eric
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Sturesson, Brian
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Ett verktyg för sågoptimering av kubb2013Independent thesis Basic level (university diploma), 10 poäng / 15 hpOppgave
    Abstract [sv]

    I detta examensarbete har ett användarvänligt verktyg skapats för att möjliggöra undersökningar av värdeutfallet vid kubbsågning på VIDA Alvesta AB. Verktyget har skapats i Microsoft Excel som för många är en känd miljö. Just nu är det svårt att få lönsamhet inom sågverksbranschen. Råvaran är dyr och det tvingar sågverken att effektivisera sin produktion. Det här verktyget har vankantsandel som viktigaste variabel eftersom det maximerar värdeutbytet genom att använda maximalt tillåtna vankanter.

    En undersökning för produkten 47x100 har gjorts med avseende att dölja vankanter med hjälp av rundade hörn med radie 3 och 5 mm. Undersökningen visade att det går att dölja en större vankant genom att öka hörnradien från 3 till 5 mm. En ytterligare åtgärd som kan utföras för att utnyttja råvaran på ett bättre sätt är att minska på råmåtten. Om råmåttet minskas med 3 % kan en ekonomisk vinning erhållas.

  • 326.
    Karlsson, Maria
    Linnéuniversitetet, Fakultetsnämnden för naturvetenskap och teknik, Institutionen för teknik, TEK.
    Underlag för utformning av statistikrapporter i ett scannersystem2011Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
    Abstract [sv]

    Denna studie syftar till att utgöra underlag och förslag till utformningen av statistikrapporter till WoodEye’s nya statistikdatabas som ingår i WoodEye 5. WoodEye 5 lanserades på Lignamässan i Hannover, 30 maj- 3 juni 2011. Förslagen har sin grund i kvalitativa intervjuer med ett urval av Innovativ Vision AB’s kunder, som tidigare visat intresse i frågan. Innovativ Visions kunder finns inom träbearbetningsindustrin, och uppvisar stora variationer i verksamhetsområde. Därför ska den nya statistikdatabasen präglas av en större valfrihet och flexibilitet, för att ett specifikt företag ska kunna göra de produktionsuppföljningar som är lämpliga för ändamålet.

    I slutet av 1960-talet påbörjades utvecklingen av automatisk virkessortering, eftersom detta skulle medföra en högre kapacitet och en jämnare avsyning i träbearbetande företag. En större mängd produkter kan tillverkas och fler sorteringsregler kan tillämpas samtidigt vid automatisk virkesavsyning jämfört med manuell avsyning. På senare år har även träindustrin påverkats av olika produktionsfilosofier, exempelvis resurssnål produktion. Detta medför att arbetet med kvalitetsteknik får en mer betydande roll i träbearbetande företag. Eftersom trä är ett heterogent material, är kvalitetsoptimering en komplex aktion. Därför har man börjat förespråka idén om rätt kvalitet för rätt ändamål, istället för att tala om hög och låg kvalitet.

    Innovativ Vision har sina rötter i den datorbaserade bildbehandlingen som bedrevs med stor framgång vid Linköpings universitet under 1980-talet. I slutet av 2011 beräknas den femte generationen WoodEye vara i drift, och i dagsläget finns tre tillhörande mjukvaruoptioner; Sorter, CrossCut och Parquet & Flooring. Sorter är en sorteringsoption, CrossCut är en kapoptimeringsoption och Parquet & Flooring är en sorteringsoption med förbättrad avsyning av färgvariationer i virket.

    I intervjuerna framkommer att de uppföljningar som referensföretagen utför idag är personal-, tillgänglighets-, och leverantörsuppföljningar samt hur den faktiska produktionen förhåller sig till den kalkylerade produktionen. Det finns stora variationer i uppföljningsverksamheten mellan företagen. Tre företag utför leverantörsuppföljningar och dessa anses vara de som har bäst rutin på uppföljningar. För optimalt genomförda uppföljningar av råvaran krävs en utvecklad defektstatistik, en funktion i statistikdatabasen som skulle innebär ett stort mervärde för kunderna. Det är framför allt kunder som använder WoodEye CrossCut som efterfrågar defektstatistik. Det beror sannolikt på att ingen motsvarighet till WoodEye Sorter’s nedklassningsstatistik finns till denna kapoptimeringsoption.

    I WoodEye 5 kommer trendstatistik genereras. Trendstatistiken blir ett verktyg för att avgöra hur det ögonblickliga produktionsutfallet förhåller sig till produktionsutfallet över tiden. Bland referensföretagen råder delade meningar om hur trendstatistiken kommer att användas; en del företag tror sig vilja göra uppföljningar baserat på informationen, medan andra enbart vill tillämpa den som ett stöd då WoodEye är i drift.

  • 327.
    Kielmann, B
    et al.
    Georg-August-University Göttingen, Germany.
    Adamopoulos, Stergios
    Georg-August-University Göttingen, Germany.
    Militz, H
    Georg-August-University Göttingen, Germany ; Technological Educational Institute of Larissa, Greece.
    Koch, G
    Federal Research Institute of Rural Areas, Forestry and Fisheries (vTI), Germany.
    Mai, C
    Georg-August-University Göttingen, Germany.
    Modification of three hardwoods with an N-methylol melamine compound and a metal-complex dye2014Inngår i: Wood Science and Technology, ISSN 0043-7719, E-ISSN 1432-5225, Vol. 48, nr 1, s. 123-136Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This study evaluated the combined modification and staining of ash, beech and maple wood with a low molecular weight N-methylol melamine compound (NMM) and a metal-complex dye. Wood samples were treated with aqueous solutions of 10, 20 and 30 wt% NMM and 5 wt% of the dye. The treatment caused the fixation of the water-soluble dye by the NMM resin. Vacuum pressure impregnation of unsealed wood blocks did not result in different solution uptake and weight percent gain after curing among the three species, but sealing of the surfaces of the wood blocks to allow penetration only into one direction revealed easiest penetrability of beech followed by maple and ash. UV micro-spectrophotometry and light microscopy indicated that NMM was partly deposited in the cell wall and partly in the lumens. Penetration of the metal-complex dye was shown by means of X-ray micro-analysis (SEM–EDX). The study shows that a combined resin modification and staining of the three wood species tested is possible and that NMM causes fixation of the water-soluble dye.

  • 328.
    Kielmann, B
    et al.
    Georg-August-University Göttingen, Germany.
    Adamopoulos, Stergios
    Georg-August-University Göttingen, Germany ; Technological Educational Institute of Thessaly, Greece.
    Militz, H
    Georg-August-University Göttingen, Germany.
    Mai, C
    Georg-August-University Göttingen, Germany.
    Decay resistance of ash, beech and maple wood modified with N-methylol melamine and a metal complex dye2014Inngår i: International Biodeterioration & Biodegradation, ISSN 0964-8305, E-ISSN 1879-0208, Vol. 89, s. 110-114Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This study evaluated the decay resistance of ash (Fraxinus excelsior L.), beech (Fagus sylvatica L.), and maple (Acer platanoides L.) wood impregnated by a full cell process with N-methylol melamine (NMM) and combined NMM-metal complex dye (NMM-BS) in aqueous solutions. Basidiomycete decay testing involved incubation with Coniophora puteana (brown rot) and Trametes versicolor (white rot) according to a modified EN 113 (1996) standard, while for the soft rot fungal resistance was evaluated following the standard ENv 807 (2001). NMM and NMM-BS modifications at a WPG range of 7–11% provided decay protection against brown rot resulting in a mass loss less than the required limit (3%). The NMM and NMM-BS modified wood showed increased resistance to white rot decay; however, a higher WPG is needed to prohibit attack from this hardwood specific fungus. The metal-complex dye alone revealed biocidal effects against basidiomycetes. An increased WPG in NMM or NMM-BS had a positive impact against soft rot decay and the lowest mass losses after 32 weeks of exposure were obtained with NMM modification at about 18–21% WPG. NMM modification at this WPG range, however, was not sufficient to protect the wood from soft rot decay. The wood of beech and maple showed slightly higher resistance to all decay types than ash, probably due to the poorer degree of modification of the latter.

  • 329.
    Kielmann, B
    et al.
    Georg-August-University Göttingen, Germany.
    Militz, H
    Georg-August-University Göttingen, Germany.
    Mai, C
    Georg-August-University Göttingen, Germany.
    Adamopoulos, Stergios
    Technological Educational Institute of Thessaly, Greece.
    Strength changes in ash, beech and maple wood modified with a N-methylol melamine compound and a metal-complex dye2013Inngår i: Wood research, ISSN 1336-4561, Vol. 58, nr 3, s. 343-350Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Ash, beech and maple wood was modified with aqueous solutions of methylated N-methylol melamine (NMM) and a metal-complex dye (BS) consisting of 10, 20, and 30 % NMM and 5 % BS. Static bending strength and stiffness, impact bending strength and hardness were examined to evaluate the suitability of modified wood for structural uses. The combined NMMBS modification resulted in significant higher dynamic (MOEdyn) and static (MOE) moduli of elasticity for all species. Beech and maple exhibited enhanced static bending strength (MOR), while that of ash was unchanged. The higher stiffness and strength of NMM-BS modified wood is attributed to its higher wood density and lower EMC and to the stiff character of NMM resin incorporated in the wood matrix. Impact bending strength decreased substantially after modification as a result of reduced pliability of treated wood. Brinell hardness significantly increased with the weight percent gain (WPG) due to modification, and, unlike the other properties, it was positively correlated with the WPG.

  • 330. Kielmann, BC
    et al.
    Militz, Holger
    Adamopoulos, Stergios
    Technological Educational Institute of Larissa, Greece.
    Combined N-Methylol melamine-colouring agent modification of hardwoods to improve their performance under use class 32012Inngår i: The Sixth European Conference on Wood Modification: Proceedings / [ed] Dennis Jones, Holger Militz, Marko Petrič, Franc Pohleven, Miha Humar, Matjaž Pavlič, University of Ljubljana , 2012, s. 437-446Konferansepaper (Fagfellevurdert)
  • 331.
    Kifetew, Girma
    et al.
    Linnéuniversitetet, Fakultetsnämnden för naturvetenskap och teknik, Institutionen för teknik, TEK.
    Nilsson, Jonaz
    Linnéuniversitetet, Fakultetsnämnden för naturvetenskap och teknik, Institutionen för teknik, TEK.
    Sandberg, Dick
    Linnéuniversitetet, Fakultetsnämnden för naturvetenskap och teknik, Institutionen för teknik, TEK.
    Is it possible to constrain moisture movement of densified wood product mechanically?2011Inngår i: Mechano-chemical transformation of wood during THM processing / [ed] Navi, P. & Roth, A, Biel Switzerland: Bern University of Applied Sciencs, Architecture, Wood and Civil Engineering , 2011, s. 67-68Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Densification of wood in the transverse direction increases the density. One of the reasons for densifying wood is to produce high quality timber from timbers of low quality. However, densified wood shows an undesired behaviour, i.e. a tendency to return to its initial dimensions when it is subjected to heat and humidity, i.e. shape memory. There are several methods to overcome the problem of shape memory.

    This study uses a three-layered cross-laminated wood panel where one of the layers is of densified wood and the other two are of normal wood together these will mechanically restrain the shape memory of the densified layer.

    The study includes three stages:

    • Densification of clear wood in the radial direction
    • Manufacture of a three-layered cross laminated composite product with densified wood as a service layer
    • Testing of the shape stability when the composite was subjected to variations relative humidity (40-85 % RH at 20°)

    The result of this study reveals the significance of service to bottom layer thickness ratio on the shape stability of the cross laminated composite. Consequently, the performance and the shape stability of the cross laminated composite were significant when the service to bottom layer thickness ratio increases. Therefore, it appears feasible to disclose the appreciable degree of shape stability, hardness and wear resistance of the product. Accordingly, cross laminated composite can be considered as one of the promising mechanical methods for improving moisture movement of densified wood product.

  • 332.
    Kifetew, Girma
    et al.
    KTH, Träteknologi.
    Sandberg, Dick
    KTH, Träteknologi.
    A Comparsion of Dot-counting and Mercury immersion Methods for Determing Density.1996Rapport (Annet vitenskapelig)
    Abstract [en]

    This paper describes two wood density determination techniques, one using the dotcounting and the other Mercury immersion and discuses the correlation between the methods. The paper includes also a short literature survey on some other wood density determination methods.

  • 333.
    Kitek Kuzman, Manja
    et al.
    University of Ljubljana, Wood Science and Technology.
    Haviarova, Eva
    Purdue University, Department of Forestry and Natural Resources, West Lafayette, IN.
    Sandberg, Dick
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Architects´ perception of modified wood: a parallel study in selected countries in Europe and selected regions in USA2017Inngår i: COST Action FP1407 3rd Conference: Wood modification research & applications / [ed] Tondi G, Posavčevič M, Kutnar A, Wimmer R., Salzburg, Kuchl, 2017, s. 151-152Konferansepaper (Fagfellevurdert)
  • 334.
    Kitek Kuzman, Manja
    et al.
    University of Ljubljana, Wood Science and Technology.
    Lähtinen, Katja
    University of Vaasa, Faculty of Business Studies, Department of Marketing, Finland.
    Sandberg, Dick
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Initiatives Supporting Timber Constructions in Finland, Slovenia and Sweden.2017Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    Presented at the IUFRO 2017 Division 5 Conference "Forest Sector Innovations for a Greener Future", Vancouver, BC, June 12-16, 2017, 18p. Initiatives Supporting Timber Constructions in Finland, Slovenia and SwedenManja KITEK KUZMAN, Katja LÄHTINEN, Dick SANDBERGUniversity of Ljubljana, Biotechnical Faculty, Department of Wood Science and Technology, Slovenia manja.kuzman@bf.uni-lj.siUniversity of Vaasa, Faculty of Business Studies, Department of Marketing, The University Consortium of Seinäjoki, Finland klahtine@uwasa.fiLuleå University of Technology, Wood Science and Engineering, Swedendick.sandberg@ltu.seAbstractFinland, Slovenia and Sweden are the three most forested countries in the European Union. While Finland and Sweden have a long tradition of building with wood, most housing in Slovenia were made with brick and stone. In Finland, knowledge of wood, an age-old building material, is actively preserved and enhanced. New wood buildings gain a contemporary twist, and are a significant part of the building stock in Finland. Swedish long tradition with timber construction is going from strength to strength thanks to the development of advanced, modern day timber structures. Sweden’s national building code has allowed the construction of multi-storey timber housing since the mid1990s. Builders and architects know that timber is not only an economical building material but that it has the added bonus of being climate friendly. Though few in number, most Slovenian timber buildings combine contemporary styling with energy efficiency measures that bring them close to passive house standards. Slovenia’s construction industry is widely recognized as advanced in the field of low energy buildings. As energy-efficient building methods gain importance, timber passive houses can play an increasingly important role in the future.In this paper, the Finnish, Slovenian and Swedish initiatives and legalization supporting timber constructions will be presented in relation to current European regulations with an emphasis on the use of wood as a sustainable architectural construction material for the future

  • 335.
    Kitek Kuzman, Manja
    et al.
    University of Ljubljana, Wood Science and Technology.
    Sandberg, Dick
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Current trends and future directions for multi-storey timber buildings2017Inngår i: Macedonian Association of Structural Engineers ( MASE) 17th International Symposium, 4-7 Sept. 2017, Ohrid, Macedonia: Book of abstracts, Ohrid: Macedonian Association of Structural Engineers , 2017, s. 205-215Konferansepaper (Fagfellevurdert)
  • 336.
    Kitek Kuzman, Manja
    et al.
    University of Ljubljana, Wood Science and Technology.
    Sandberg, Dick
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Development of multi-storey buildings and future trends2017Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Extensive research has shown that material-neutral building regulations are preferable and, for over a decade, function-based regulations have been common in many European countries, and this have contributed to an increase in the construction of multi-storey timber buildings. As one example, in the Scandinavia the development since mid-1990th of multi-storey timber buildings can be described as a success story, but there is also many other countries that have a positive development in timber construction. There is a great market potential for the use of wood in all types of buildings employing a combination of digital design and CNC (computer numerical control) processing. The construction engineers know how to make use of the digital tools; they have geometric imagination capabilities and construction know-how while the architects have ambitious ideas for building extraordinary projects. Digital design and production using CAE (computer-aided engineering), CAD (computer-aided design) and CAM (computer-aided manufacturing) have allowed timber construction to forge ahead into new dimensions of design. Innovative connections, modern wood-based materials and cutting-edge CNC milling offer entirely new possibilities and shape wood into almost any conceivable form. This paper gives an overview of the development of multi-storey timber building with a special focus on future trends in combination of digital design as flexible planning and design tools in combination with CNC processing to design and build extraordinary projects. Keywords: A rchitecture; timber construction; digital design; wood processing

  • 337.
    Kliger, Robert
    et al.
    Chalmers University of Technology, Sweden.
    Johansson, Marie
    Chalmers University of Technology, Sweden.
    Ormarsson, Sigurdur
    Chalmers University of Technology, Sweden.
    Bäckström, Magnus
    Chalmers University of Technology, Sweden.
    The Builders'€™ View on Drying Quality and its Consequences2004Inngår i: Proceedings of COST E15 - Drying timber for value-added products, Athens, Greece, 22-24 April. 01/01/2004, 2004Konferansepaper (Fagfellevurdert)
  • 338.
    Konnerth, Johannes
    et al.
    BOKU-University of Natural Resources and Applied Life Sciences, Austria.
    Eiser, Martina
    Competence Center for Wood Composites and Wood Chemistry, Austria.
    Jäger, Andreas
    Vienna University of Technology, Austria.
    Bader, Thomas K.
    Vienna University of Technology, Austria.
    Hofstetter, Karin
    Follrich, Jürgen
    Competence Center for Wood Composites and Wood Chemistry, Austria.
    Ters, Thomas
    BOKU-University of Natural Resources and Applied Life Sciences, Austria.
    Hansmann, Christian
    Competence Center for Wood Composites and Wood Chemistry, Austria.
    Wimmer, Rupert
    ood Technology and Wood-based Composites Unit, Germany.
    Macro- and micro-mechanical properties of red oak wood (Quercus rubra L.) treated with hemicellulases2010Inngår i: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, Vol. 64, nr 4, s. 447-453Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Red oak wood (Quercus rubra L.) samples were submitted to an enzymatic treatment with a commercial mixture of hemicellulases aiming at the selective depolymerization and removal of the hemicelluloses. Mechanical properties of treated samples were characterized and compared with untreated samples at two hierarchical levels. At the macrolevel, tensile properties revealed to be less sensitive to degradation of the cell wall matrix compared to compression and hardness properties. Results obtained through indentation at the microlevel indicated that hardness and the so-called reduced modulus of treated wood were significantly lowered. Accordingly, hardness and reduced elastic modulus have proven to be most sensitive to modification of the cell wall matrix by reducing the content of hemicelluloses. It is proposed that transversal and shear stresses, which are mainly carried by the cell wall matrix, are additional parameters having strong effects on elastic modulus obtained by nanoindentation. Micromechanical modeling was employed to confirm the observed changes. There is consistency between the measured and the modeled properties, obtained at both the microlevel and the macrolevel of wood.

  • 339. Kortsalioudakis, Nathanail
    et al.
    Petrakis, Panagiotis
    Moustaizis, Stavros
    Voulgaridis, Elias
    Adamopoulos, Stergios
    Karastergiou, Sotirios
    Passialis, Costas
    An application of a laser drilling technique to fir and spruce wood specimens to improve their permeability2015Inngår i: Innovation in Woodworking Industry and Engineerings Design, ISSN 2367-6663, nr 1, s. 5-13Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this work, the application of a laser drilling technique on fir (Abies borisii regis) and spruce (Picea excelsa) wood and a new approach of improvement the wood permeability is investigated. This technique is focusing on increasing the permeability of wood after surface drilling by a high power laser source. The research was involving the establishment of an effective drilling pattern protocol, which will not substantially affect the mechanical strength of wood and to improve its permeability. All lateral surfaces of the wood specimens, 2 × 2 cm in cross section and 34 cm long, were drilled by laser to a depth of 4 mm (1/5 of specimen thickness) with two drilling patterns (distance between holes 10 × 10 mm and 10 × 20 mm). Preliminary results showed that laser drilling is a promising method for improvement of wood permeability without significant effect on its mechanical strength, and this is very important for an effective treatment of the refractory to impregnation fir and spruce wood.

  • 340. Kostiainen, K.
    et al.
    Kaakinen, S.
    Saranpää, P.
    Sigurdsson, B. D.
    Lundqvist, Sven-Olof
    RISE., STFI-Packforsk.
    Linder, S.
    Vapaavuori, E.
    Stem wood properties of mature Norway spruce after 3 years of continuous exposure to elevated [CO2] and temperature2009Inngår i: Global Change Biology, ISSN 1354-1013, E-ISSN 1365-2486, Vol. 15, nr 2, s. 368-379Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The objective of the study was to investigate the interactive effects of elevated atmospheric carbon dioxide concentration, [CO2], and temperature on the wood properties of mature field-grown Norway spruce (Picea abies (L.) Karst.) trees. Material for the study was obtained from an experiment in Flakaliden, northern Sweden, where trees were grown for 3 years in whole-tree chambers at ambient (365 ÎŒmol mol-1) or elevated [CO2] (700 ÎŒmol mol-1) and ambient or elevated air temperature (ambient +5.6°C in winter and ambient +2.8°C in summer). Elevated temperature affected both wood chemical composition and structure, but had no effect on stem radial growth. Elevated temperature decreased the concentrations of acetone-soluble extractives and soluble sugars, while mean and earlywood (EW) cell wall thickness and wood density were increased. Elevated [CO2] had no effect on stem wood chemistry or radial growth. In wood structure, elevated [CO2] decreased EW cell wall thickness and increased tracheid radial diameter in latewood (LW). Some significant interactions between elevated [CO2] and temperature were found in the anatomical and physical properties of stem wood (e.g. microfibril angle, and LW cell wall thickness and density). Our results show that the wood material properties of mature Norway spruce were altered under exposure to elevated [CO2] and temperature, although stem radial growth was not affected by the treatments. © 2008 The Authors Journal compilation © 2008 Blackwell Publishing.

  • 341. Kostiainen, K.
    et al.
    Saranpää, P.
    Lundqvist, S..-O.
    RISE, Innventia.
    Kubiske, M.E.
    Vapaavuori, E.
    Wood properties of Populus and Betula in long-term exposure to elevated CO2 and O32014Inngår i: Plant, Cell and Environment, ISSN 0140-7791, E-ISSN 1365-3040, Vol. 37, nr 6, s. 1452-1463Artikkel i tidsskrift (Fagfellevurdert)
  • 342.
    Kotsalainen, Stina
    Linköpings universitet, Institutionen för konstruktions- och produktionsteknik.
    Undersökning av värmebehandlingsmetod som färgar trä2005Independent thesis Basic level (professional degree), 20 poäng / 30 hpOppgave
    Abstract [sv]

    Detta examensarbete har utförts för trägolvtillverkaren Tarketts räkning och syftet har varit att utvärdera en särskild metod som färgar trä. Metoden innebär att trä behandlas i vatten i en viss tid och temperatur varvid en färgändring påstods erhållas. Målet har varit ge de nordiska träslagen björk och bok en mörkare färg som liknar exotiska trädslag.

    För att utvärdera metoden genomfördes först en teoretisk utvärdering för att få förståelse för vad som händer i träet när det utsätts för denna behandling och sedan en praktisk utvärdering enligt principen för flerfaktorförsök.

    Arbetet har resulterat i vetskapen om att träet verkligen får en viss färgändring genom att behandla det enligt den särskilda metoden. Hur stor färgförändring som erhålls beror främst på processens temperatur men även tid, ty dessa faktorer samverkar. Metoden uppvisar repeternoggrannhet, dvs uppnådd färg vid bestämda parametrar är konstant och den erhållna färgen är dessutom beständig. Men, metoden påverkar träet på ett flertal negativa sätt. Vid torkning av de behandlade trästavarna uppstår ändsprickor och vissa stavar blir skeva. Utbytet som erhålls beror främst på hur hårt stavarna behandlas. Låga temperaturer, 100 C, krävs om ett bra utbyte ska erhållas. Andra egenskaper som blir försämrade är träets vätbarhet och hållfasthet. En försämrad vätbarhet innebär i sin tur en försämrad limbarhet eftersom träet inte väter limmet tillräckligt bra. Hårdare behandlat trä fick en lägre vätbarhet än mildare behandlad. Men en försämrad vätbarhet är inte bara negativt utan det innebär även att träets dimensionsstabilitet förbättras. Träets fuktrörelser blir alltså inte lika stora vid klimatförändringar, något som också bevisades med sk klimattester.

    Utvärderingen resulterade även i vetskapen om att processvattnet från infärgningsmetoden är miljöfarligt och måste renas. Att rena vattnet är svårt då de miljöfarliga ämnena som det innehåller är lösta i vattnet, så för att kunna ta hand om reningsprocessen behöver Tarkett kunskap om olika reningsprocesser men även utrustning som kan kräva stora investeringar.

    Det är svårt att bedöma om infärgningsmetoden är användbar för Tarkett eller ej. Min rekommendation avgörs nämligen av vilket färgändring som Tarkett tycker är den mest tilltalande. Föredrar Tarkett den mörkaste erhållna färgen rekommenderar jag inte Tarkett att gå vidare med infärgningsmetoden eftersom ett så pass dåligt utbyte erhålls. Utbytet kan eventuellt förbättras men det måste i så fall undersökas närmare. Föredrar Tarkett däremot en ljusare färg som erhållits för andra försök är infärgningsmetoden värd att undersöka vidare.

  • 343.
    Kumar, Anuj
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT). Czech Technical University in Prague, Czech Republic.
    Richter, Jan
    Czech Technical University in Prague, Czech Republic.
    Tywoniak, Jan
    Czech Technical University in Prague, Czech Republic.
    Hajek, Petr
    Czech Technical University in Prague, Czech Republic.
    Adamopoulos, Stergios
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Šegedin, Urban
    University of Ljublijana, Slovenia.
    Marko, Petrič
    University of Ljublijana, Slovenia.
    Surface modification of Norway spruce wood by octadecyltrichlorosilane (OTS) nanosol by dipping and water vapour diffusion properties of the OTS-modified wood2018Inngår i: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, Vol. 72, nr 1, s. 45-56Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The present research deals with a simple dipping method to insert octadecyltrichlorosilane (OTS) into cell walls of spruce wood and to deposit OTS layers on its inner and outer surfaces. Distribution and chemical interactions of OTS with wood polymers has been investigated by scanning electron microscopy-energy-dispersive X-ray spectroscopy (SEM-EDS), X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FTIR) spectroscopy. The OTS/n-hexane solution penetrated into wood via capillary forces through ray tracheids and bordered pits and was deposited as OTS organic-inorganic layers on wood cell walls. The hypothesis is supported by the results, according to which the OTS molecules are hydrolysed by the wood moisture and by free OH groups of the cell wall components. The hydrolysed OTS molecules react with the OH groups and elevate the hydrophobicity of wood.

  • 344.
    Kymäläinen, Maija
    et al.
    Aalto University, Finland.
    Hautamäki, Saara
    Aalto University, Finland.
    Lillqvist, Kristiina
    KTH Royal Institute of Technology, Sweden.
    Segerholm, Kristoffer
    RISE - Research Institutes of Sweden, Bioekonomi. KTH Royal Institute of Technology, Sweden.
    Rautkari, Lauri
    Aalto University, Finland.
    Surface modification of solid wood by charring2017Inngår i: Journal of Materials Science, ISSN 0022-2461, E-ISSN 1573-4803, Vol. 52, nr 10, s. 6111-6119Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Most wooden structures for outdoor applications require repetitive maintenance operations to protect the surfaces from adverse effects of weathering. One-sided surface modification of boards with a relatively fast charring process has the potential to increase the durability and service life of wooden claddings. To assess some weathering-related effects on surface charred wood, spruce and pine sapwood were subjected to a series of long charring processes (30–120 min) at a moderate temperature of 250 °C and to a short one (30 s) at a high temperature of 400 °C. The wettability and contact angles of treated samples were investigated, and the heat transfer was measured along with the micromorphological changes taking place in the material. The result revealed an increased moisture resistance of charred spruce sapwood and an increased water uptake of pine sapwood. The contact angles of both wood species improved compared to references. Heat conduction measurement revealed that only a thin section of the wood was thermally modified. Some micromorphological changes were recorded, especially on the inside walls of the lumina. The results show that spruce sapwood has an improved resistance towards moisture-induced weathering, but more studies are needed to unlock the potential of surface charred wood.

  • 345.
    Källbom, Susanna
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial.
    Rautkari, Lauri
    Department of Forest Products Technology, Aalto University.
    Wålinder, Magnus
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial.
    Johansson, Leena-Sisko
    Aalto University, Finland.
    Campbell, JM
    Department of Forest Products Technology, Aalto University.
    Segerholm, Kristoffer
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial. SP Technical Research Institute of Sweden, Sweden.
    Jones, Dennis
    SP Technical Research Institute of Sweden.
    Laine, Kristiina
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial.
    Water vapour sorption characteristics and surface chemical composition of thermally modified spruce (Picea abies karst)2016Inngår i: International Wood Products Journal, ISSN 2042-6445, E-ISSN 2042-6453Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The objective of this work was to study the hygroscopicity and surface chemical composition of thermally modified (TM) spruce. An effort was also made to study if those features were influenced by a previous exposure to a significant increase in relative humidity (RH). TM and unmodified Norway spruce (Picea abies Karst) samples, both in solid and ground form, were prepared. Water vapour sorption characteristics of the ground samples were obtained by measuring sorption isotherms using a dynamic vapour sorption (DVS). The surface chemical composition of the solid samples, both acetone extracted and non-extracted, were analysed using X-ray photoelectron spectroscopy (XPS). The DVS analysis indicated that the TM wood exposed to the 75% RH revealed a decrease in isotherm hysteresis. The XPS analysis indicated a decrease of acetone extractable or volatile organic components and a relative increase of non-extractable components for the samples exposed to the increased RH condition.

  • 346.
    Köpcke, Viviana
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Träkemi och massateknologi.
    Conversion of Wood and Non-wood Paper-grade Pulps to Dissolving-grade Pulps2010Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Dissolving-grade pulps are commonly used for the production of cellulose derivatives and regenerated cellulose. To obtain products of high quality, these so-called "special" pulps must fulfill certain requirements, such as high cellulose content, low hemicellulose content, a uniform molecular weight distribution and high cellulose reactivity. Most, if not all, of the commercial dissolving pulps accomplish these demands to a certain extent. Nevertheless, achieving high cellulose accessibility as well as solvent and reagent reactivity is not an easy task due to the compact and complex structure presented by the cellulose.

    In the first part of this work, three commercial monocomponent endoglucanases were investigated with the purpose of enhancing the cellulose accessibility and reactivity of a hardwood dissolving pulp. A monocomponent endoglucanase with a cellulose-binding domain (CBD) was shown to significantly improve the cellulose reactivity. The positive effect of this enzyme on dissolving-grade pulps was also observed on paper-grade pulps.

    The main focus of the forest industry is the production of paper-grade pulps. Paper-grade pulps are mostly produced by the kraft process. In contrast, dissolving-grade pulps are produced by the sulfite and prehydrolysis kraft processes due to the high purity required for these pulps. The kraft process is known for being the most efficient process in terms of energy and chemical recovery, which makes the production costs of paper-grade pulps lower than those of sulfite dissolving-grade pulps. Besides, the production of dissolving pulps present, among others, higher capital and chemical costs than paper-grade pulps.

    Therefore, the viability of converting paper-grade pulps into dissolving pulps is brought into a question. However, this task is not simple because paper-grade pulps contain a lower cellulose content and a higher hemicellulose content than dissolving pulps. They also present lower cellulose reactivity and an inhomogeneous molecular weight distribution. As a consequence, the second part of this work focused on the study of the feasibility of converting kraft pulps into dissolving pulps. Several sequences of treatments of hardwoods and non-wood pulps were investigated. The best sequence for each suitable pulp was developed, and the parameters involved were optimized. After several attempts, it was demonstrated that pulps from birch, eucalypt and sisal fulfill the requirements of a commercial dissolving pulp for the viscose process after being subjected to a sequence of treatments that included two commercial enzymes, a xylanase and a monocomponent endoglucanase, and alkali extraction steps.

     

  • 347.
    Köpcke, Viviana
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Träkemi och massateknologi.
    Improvement on cellulose accessibility and reactivity of different wood pulps2008Licentiatavhandling, med artikler (Annet vitenskapelig)
    Abstract [sv]

    Cellulosans tillgänglighet och reaktivitet är nyckelparametrar vid framställning av regenererad cellulosa och cellulosaderivat. Det är välkänt att på grund av cellulosans kristallina struktur är tillgängligheten begränsad för lösningsmedel och olika reagens. Till exempel kan en inhomogen substitution av hydroxylgrupperna i cellulosakedjan resultera i cellulosaderivat av sämre kvalitet. Baserat på detta har en del av arbetet i denna studie fokuserat på att förbättra cellulosans tillgänglighet och reaktivitet genom att studera effekten av olika enzymatiska behandlingar med monokomponent endoglukanaser. Resultaten visar att närvaron av en cellulosabindande domän fyller en viktig funktion för att öka cellulosans reaktivitet, men strukturen för den katalytiska domänen visade sig ha den största inverkan på cellulosans tillgänglighet. I kompletterande studier har även effekten av en mekanisk förbehandling i kombination med enzymatisk behandling utvärderats. Kombinationen av förbehandlingarna resulterade i en positiv effekt, cellulosans reaktivitet kunde ökas i större omfattning.

    I dag används huvudsakligen dissolvingmassor som råvara vid framställning av cellulosaregenerat och cellulosaderivat. Kraven för dessa s.k. specialmassor är högt cellulosainnehåll samt lågt hemicellulosa- respektive lignininnehåll. På grund av dessa specifika krav är produktionskostnaderna för dessa massor högre än konventionella sulfatmassor. Den andra delen av studien har därför fokuserat på möjligheten att använda dessa sulfatmassor som dissolvingmassa. Det har visats att kombinationen av enzymatiska behandlingar med monokomponent endoglukanas och xylanas följt av ett alkaliskt steg kan resultera i massor där kraven uppfylls med avseende på cellulosans reaktivitet, och cellulosa- respektive hemicellulosainnehåll.

  • 348.
    Köpcke, Viviana
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Träkemi och massateknologi.
    Ibarra, David
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Träkemi och massateknologi.
    Ek, Monica
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Träkemi och massateknologi.
    Increasing accessibility and reactivity of paper grade pulp by enzymatic treatment for use as dissolving pulp2008Inngår i: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 23, nr 4, s. 363-368Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

     In this study, the feasibility of using different kraft pulps as dissolving pulps for the viscose process was investigated. Two different bleached hardwood kraft pulps from eucalypt (Eucalyptus globulus) and birch (Betula pendula) were subjected to several enzymatic and chemical pretreatments in order to improve the accessibility and reactivity of the pulps and to reduce the hemicellulose content. Enzymatic treatments were carried out using a commercial monocomponent endoglucanase and a commercial xylanase. Chemical treatment consisted of an alkali extraction. The effects of these pretreatments on reactivity and viscosity were assayed. In both pulps, the endoglucanase enhanced the cellulose reactivity and reduced the viscosity. The sequential combination of xylanase and endoglucanase enhanced the positive effect of endoglucanase treatment alone for eucalypt but showed no major effect for birch. The addition of an alkali extraction step after the xylanase followed by endoglucanase treatment as a final step significantly reduced the hemicellulose content to 24% while the reactivity reached the value of a commercial dissolving pulp (65-70%). The viscosity, on the other hand, showed a considerably decrease.

  • 349.
    Köpcke, Viviana
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Träkemi och massateknologi.
    Nanko, Hiroki
    Ek, Monica
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Träkemi och massateknologi.
    The effect of different monocomponent endoglucanases on cellulose accessibility in dissolving pulpsManuskript (Annet vitenskapelig)
  • 350.
    Laine, Kristiina
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial.
    Segerholm, Kristoffer
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial. SP Tech Res Inst Sweden.
    Wålinder, Magnus
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial.
    Rautkari, Lauri
    Hughes, Mark
    Wood densification and thermal modification: hardness, set-recovery and micromorphology2016Inngår i: Wood Science and Technology, ISSN 0043-7719, E-ISSN 1432-5225, Vol. 50, nr 5, s. 883-894Artikkel i tidsskrift (Fagfellevurdert)
    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.

45678910 301 - 350 of 710
RefereraExporteraLink til resultatlisten
Permanent link
Referera
Referensformat
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annet format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annet språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf