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Adamopoulos, StergiosORCID iD iconorcid.org/0000-0002-6909-2025
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Publications (10 of 128) Show all publications
Kumar, A., Ryparová, P., Hosseinpourpia, R., Adamopoulos, S., Prošek, Z., Žigone, J. & Petrič, M. (2019). Hydrophobicity and resistance against microorganisms of heat and chemically crosslinked poly(vinyl alcohol) nanofibrous membranes. Chemical Engineering Journal, 360, 788-796
Open this publication in new window or tab >>Hydrophobicity and resistance against microorganisms of heat and chemically crosslinked poly(vinyl alcohol) nanofibrous membranes
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2019 (English)In: Chemical Engineering Journal, ISSN 1385-8947, E-ISSN 1873-3212, Vol. 360, p. 788-796Article in journal (Refereed) Published
Abstract [en]

Poly(vinyl alcohol) (PVA) is a water-soluble, semi-ionic and biocompatible polymer with excellent chemical and thermal stability. The chemical crosslinking of PVA membrane improve its stability towards humidity and water. In the present work, PVA nanofibrous membranes were fabricated using roller electrospinning techniques. The prepared membranes were crosslinked by heat treatment, glutaraldehyde dipping, and glutaraldehyde vapour. Furthermore, octadecyltrichlorosilane (OTS) treatment was used for hydrophobization of the crosslinked membranes. The prepared crosslinked membranes were analysed by scanning electron microscopy (SEM) and Fourier-transform infrared spectroscopy (FTIR). The hydrophobization of PVA nanofibrous membranes were analysed by employing optical goniometer and auto-dynamic vapour sorption (AVS) techniques. Further, the PVA membranes were tested against algae and mould growth at in-vitro laboratory conditions. The SEM and FTIR results revealed significant differences in the morphology of the PVA nanofibrous membranes and in chemical bond formation due to crosslinking treatments. Water contact angle and AVS data confirmed a hydrophobization of PVA membranes by the treatments.

National Category
Polymer Technologies Other Materials Engineering
Research subject
Chemistry, Organic Chemistry
Identifiers
urn:nbn:se:lnu:diva-79195 (URN)10.1016/j.cej.2018.12.029 (DOI)
Available from: 2018-12-13 Created: 2018-12-13 Last updated: 2019-03-21Bibliographically approved
van Blokland, J., Olsson, A., Oscarsson, J. & Adamopoulos, S. (2019). Prediction of bending strength of thermally modified timber using high-resolution scanning of fibre direction. European Journal of Wood and Wood Products
Open this publication in new window or tab >>Prediction of bending strength of thermally modified timber using high-resolution scanning of fibre direction
2019 (English)In: European Journal of Wood and Wood Products, ISSN 0018-3768, E-ISSN 1436-736XArticle in journal (Refereed) Epub ahead of print
Abstract [en]

The market share of thermally modified wood (TMW) has increased in Europe during the past few years as an environmentally friendly and durable building product. However, TMW products of today are not permitted for use in structural applications, because the reduction in strength that is caused by thermal treatment cannot be accounted for. The purpose of this paper was to investigate the bending properties of thermally modified timber (TMT) of Norway spruce, and to explore possibilities to predict the bending properties of TMT. A sample of 100 boards from a 2X-log sawing pattern of 100 logs was thermally modified according to the ThermoWood® process, while the mirror 100 boards served as an unmodified control sample. Two non-destructive methods were employed: (1) a novel method based on scanning of fibre directions to obtain the lowest edgewise bending modulus of elasticity (MOE) along a board, and (2) a conventional excitation method to determine the first axial resonance frequency used to calculate the axial dynamic MOE. Finally, the boards were bent to failure according to European standard EN 408. Despite the fact that bending strength was reduced by 42% due to thermal treatment, the type and location of failure in TMT remained related to the presence of knots. Prediction of bending strength based on local fibre direction and axial dynamic MOE, gave coefficients of determination of 0.51 for the thermally modified boards and 0.69 for the control boards, whereas axial dynamic MOE alone gave 0.46 and 0.57, respectively. These results indicate that although Norway spruce TMT has lower bending strength compared to unmodified timber, predictions of the bending strength can be made with good accuracy.

Keywords
axial dynamic excitation, fibre angle, four-point bending, grade determining properties, machine strength grading, ThermoWood®, tracheid effect
National Category
Building Technologies Wood Science
Identifiers
urn:nbn:se:lnu:diva-80374 (URN)10.1007/s00107-019-01388-w (DOI)
Available from: 2019-02-11 Created: 2019-02-11 Last updated: 2019-03-21
Hosseinpourpia, R., Adamopoulos, S. & Parsland, C. (2019). Utilization of different tall oils for improving the water resistance of cellulosic fibers. Journal of Applied Polymer Science, 136(13), Article ID 47303.
Open this publication in new window or tab >>Utilization of different tall oils for improving the water resistance of cellulosic fibers
2019 (English)In: Journal of Applied Polymer Science, ISSN 0021-8995, E-ISSN 1097-4628, Vol. 136, no 13, article id 47303Article in journal (Refereed) Published
Abstract [en]

This study was conducted to assess the effect of the pulping by-products crude tall oil (CTO), distilled tall oil (DTO), andtall oil fatty acid (TOFA) on dynamic water vapor sorption behavior, interfiber strength, and thermal stability of cellulosic paper-sheets.The results were compared against those obtained in cellulose papers treated with the conventional petroleum-derived hydrophobicagent hydrowax and in untreated ones. The tall oil treatments caused strong reduction in equilibrium moisture content of the paper-sheets during adsorption and desorption runs. The same trend was noticed for the hydrowax-treated papers, however, it was lesspronounced than the CTO-treated and DTO-treated samples in the relative humidity range of 75–95%. The sorption hysteresis was con-siderably decreased after the treatments. The ultimate dry-tensile strengths of the paper-sheets were significantly reduced by TOFA andhydrowax treatments, while CTO and DTO showed comparable strength as that of untreated control. The ultimate wet-strengths of thepaper-sheets were improved after the treatments. The thermal stability of the specimens was improved by the tall oil treatments, and thehydrowax-treated samples illustrated lower degradation temperature than the untreated control. The results are promising for the use oftall oils as alternative hydrophobic agents of cellulosicfiber-based products, such as wood panels and paper packaging.

Place, publisher, year, edition, pages
Wiley-Blackwell, 2019
National Category
Wood Science Composite Science and Engineering Paper, Pulp and Fiber Technology Bio Materials Polymer Chemistry
Research subject
Technology (byts ev till Engineering), Forestry and Wood Technology
Identifiers
urn:nbn:se:lnu:diva-78872 (URN)10.1002/app.47303 (DOI)000454418300034 ()
Funder
Vinnova, 2015‐04825The Kamprad Family Foundation, 20160052
Available from: 2018-11-19 Created: 2018-11-19 Last updated: 2019-03-19Bibliographically approved
Adamopoulos, S., Ahmed, S. A. & Lankveld, C. (2018). Acoustic properties of acetylated wood under different humid conditions and its relevance for musical instruments. In: Jos Creemers, Thomas Houben, Bôke Tjeerdsma, Holger Militz and Brigitte Junge (Ed.), Proceedings of the 9th European Conference on Wood Modification 2018, Arnhem, The Netherlands: . Paper presented at 9th European Conference on Wood Modification (ECWM9), September 17-18, Arnhem, The Netherlands (pp. 61-61). The Netherlands: Practicum
Open this publication in new window or tab >>Acoustic properties of acetylated wood under different humid conditions and its relevance for musical instruments
2018 (English)In: Proceedings of the 9th European Conference on Wood Modification 2018, Arnhem, The Netherlands / [ed] Jos Creemers, Thomas Houben, Bôke Tjeerdsma, Holger Militz and Brigitte Junge, The Netherlands: Practicum , 2018, p. 61-61Conference paper, Oral presentation with published abstract (Refereed)
Abstract [en]

In musical instrument making, less expensive wood species and materials with good characteristics and acoustical properties can provide potentials to find alternatives to the traditional exotic wood species used today. Modified wood could be such a choice if shows similar sound characteristics to wood coming from endangered and expensive tropical species with problematic commercial availability. In musical instruments, the overall functionality depends on the contribution of wood to different material performance indexes like sound radiation coefficient (R), characteristic impedance (z) and acoustic conversion efficiency (ACE). In this study, the performance indexes were measured for acetylated beech, maple and radiata pine and compared with these obtained for the reference wood materials maple, mahogany, alder and ash. A non-destructive free-free flexural vibration test method was used at constant temperature (20oC) but in different humid conditions- dry (35% RH), standard (65% RH) and wet (85% RH). Dimensional changes in the different humid conditions were also taken in account. Acetylated wood showed lower EMC with higher dimensional stability at each humidity level as compared with the reference wood materials. These properties are considered important factors for making quality musical instruments. Based on the acoustical properties, acetylated wood materials, especially radiata pine, showed good potential for use for musical instruments where specific characteristics of sound are required. However, the other types of acetylated wood can also be used for specific musical instruments.

Place, publisher, year, edition, pages
The Netherlands: Practicum, 2018
Keywords
Acoustic conversion efficiency, damping, equilibrium moisture content, free-free flexural vibration, volumetric shrinkage
National Category
Wood Science Chemical Engineering Polymer Technologies
Research subject
Technology (byts ev till Engineering), Forestry and Wood Technology
Identifiers
urn:nbn:se:lnu:diva-77908 (URN)
Conference
9th European Conference on Wood Modification (ECWM9), September 17-18, Arnhem, The Netherlands
Available from: 2018-09-20 Created: 2018-09-20 Last updated: 2019-03-18Bibliographically approved
Ahmed, S. A. & Adamopoulos, S. (2018). Acoustic properties of modified wood under different humid conditions and their relevance for musical instruments. Applied Acoustics, 140, 92-99
Open this publication in new window or tab >>Acoustic properties of modified wood under different humid conditions and their relevance for musical instruments
2018 (English)In: Applied Acoustics, ISSN 0003-682x, Vol. 140, p. 92-99Article in journal (Refereed) Published
Abstract [en]

In musical instrument making, there is a strong need to find alternatives to the traditional endangered and expensive tropical wood species used today. The present study examined whether different commercial and experimental modified wood materials have the necessary acoustic qualities under different humid conditions (dry, standard and wet) to contribute to the use of raw materials for wooden musical instruments. The materials were thermally-modified wood (ash, aspen and birch), acetylated wood (beech, maple and radiata pine), melamine- and phenol formaldehyde-treated beech and furfurylated Scots pine (Kebony Scots pine). Investigations involved physical (density ρ, Equilibrium moisture content EMC, volumetric shrinkage) and dynamic elastic testing by a free-free flexural vibration method to determine various acoustic characteristics: specific dynamic modulus (MOEdyn/ρ), damping coefficient (tanδ), speed of sound (c), specific acoustic impedance (z), sound radiation coefficient (R) and acoustic conversion efficiency (ACE). The modified materials and especially acetylated wood showed low EMC values and high dimensional stability at each humidity level, which are considered important factors for making quality musical instruments. Based on the obtained value ranges of all acoustical properties, the different modified wood materials could find uses in musical instruments where specific characteristics of sound are required. Furthermore, most of the modified materials showed an excellent acoustic performance in the three humid conditions based on a high ACE and low tanδ. Furfurylated Scots pine and phenol formaldehyde-treated beech showed an inferior acoustic quality with the lowest ACE and the highest tanδ, which is a less favourable combination for most of the musical instruments.

Place, publisher, year, edition, pages
Elsevier, 2018
Keywords
Wood modification; Dimensional stability; Free-free flexural vibration; Dynamic elastic modulus; Damping; Sound velocity; Sound radiation; Acoustic impedance; Acoustic conversion efficiency
National Category
Wood Science
Research subject
Physics, Waves and Signals
Identifiers
urn:nbn:se:lnu:diva-74511 (URN)10.1016/j.apacoust.2018.05.017 (DOI)000440121900010 ()
Available from: 2018-05-24 Created: 2018-05-24 Last updated: 2019-03-19Bibliographically approved
Hosseinpourpia, R., Adamopoulos, S. & Mai, C. (2018). Analysis of the vapour sorption behaviour of wood modified with thermosetting resins with Hailwood-Horrobin and Excess Surface Work models. In: Spanic N.,Zupcic I. (Ed.), 29th International Conference on Wood Science and Technology, ICWST 2018: Implementation of Wood Science in Woodworking Sector - Proceedings: . Paper presented at 29th International Conference on Wood Science and Technology: Implementation of Wood Science in Woodworking Sector, ICWST 2018; Zagreb; Croatia; 6 -7 December 2018 (pp. 87-92). University of Zagreb
Open this publication in new window or tab >>Analysis of the vapour sorption behaviour of wood modified with thermosetting resins with Hailwood-Horrobin and Excess Surface Work models
2018 (English)In: 29th International Conference on Wood Science and Technology, ICWST 2018: Implementation of Wood Science in Woodworking Sector - Proceedings / [ed] Spanic N.,Zupcic I., University of Zagreb , 2018, p. 87-92Conference paper, Published paper (Refereed)
Abstract [en]

Wood modification is a well-known technology to enhance the dimensional stability of wood and the resistance to abiotic and biotic degradation. Impregnation modification of wood with thermosetting resins, such as melamine formaldehyde (MF) or phenol formaldehyde (PF), alters the material properties of wood through formation of a three-dimensional network within the cell wall. This work investigates the vapour sorption behaviour of Scots pine (Pinus sylvestris L.) micro-veneers modified with MF and PF resins by means of Hailwood-Horrobin (H-H) and excess surface work (ESW) models. The analysed sorption data indicated that the available sorption sites were increased in the modified samples compared to the unmodified controls due to an increase of the monolayer sorption. However, modification resulted in a considerable reduction of the multilayer sorption. This could be attributed to the formation of a rigid, three-dimensional corset within the cell wall formed by auto-polymerization reactions of resin monomers and oligomers, which is known to reduce the cell wall swell-ability upon water absorption.

Place, publisher, year, edition, pages
University of Zagreb, 2018
National Category
Wood Science
Identifiers
urn:nbn:se:lnu:diva-79193 (URN)978-953-292-059-8 (ISBN)
Conference
29th International Conference on Wood Science and Technology: Implementation of Wood Science in Woodworking Sector, ICWST 2018; Zagreb; Croatia; 6 -7 December 2018
Available from: 2018-12-13 Created: 2018-12-13 Last updated: 2019-03-21Bibliographically approved
van Blokland, J., Adamopoulos, S., Olsson, A. & Oscarsson, J. (2018). Bending properties and strain fields around knots in thermally modified timber. In: Jos Creemers, Thomas Houben, Bôke Tjeerdsma, Holger Militz and Brigitte Junge (Ed.), : . Paper presented at 9th European Conference on Wood Modification (ECWM), 17-18 September 2018, Bugers’ Zoo, Arnhem, The Netherlands.
Open this publication in new window or tab >>Bending properties and strain fields around knots in thermally modified timber
2018 (English)In: / [ed] Jos Creemers, Thomas Houben, Bôke Tjeerdsma, Holger Militz and Brigitte Junge, 2018Conference paper, Published paper (Refereed)
Abstract [en]

Thirty-two (32) boards of Norway spruce with cross-sectional dimensions of 145×45 mm2 were first tested non-destructively in a four-point static bending test, were then thermally modified according to the ThermoWood® process, and were finally tested destructively in the mentioned test set up. For one of these boards, the 2D strain fields occurring due to pure bending were recorded, both before and after thermal modification, over the surface of a knotty part of the board using a non-contact optical deformation measurement system. The objectives were to get more insight into the static bending behaviour of thermally modified timber (TMT), specifically with regard to the local and global modulus of elasticity (MOE) and their respective relationship to bending strength, and the strain development around a cluster of knots. The bending strength was significantly reduced by thermal treatment, whereas the effect on the MOEs was limited. Linear regression analyses demonstrated that bending strength of TMT can be predicted by employing stiffness as indicating property. Strain field measurements showed that at the examined levels of loading the quantity and distribution of strains in a knotty area were not influenced by thermal modification. It was therefore suggested that the influence of thermal modification on global stiffness, as well as on local stiffness around knots, is limited.

Keywords
four-point bending, modulus of elasticity, Norway spruce, strain measurement, strength prediction, ThermoWood®
National Category
Wood Science Building Technologies
Identifiers
urn:nbn:se:lnu:diva-77974 (URN)
Conference
9th European Conference on Wood Modification (ECWM), 17-18 September 2018, Bugers’ Zoo, Arnhem, The Netherlands
Available from: 2018-09-24 Created: 2018-09-24 Last updated: 2019-03-21
Hosseinpourpia, R., Adamopoulos, S. & Mai, C. (2018). Effects of acid pre-treatments on the swelling and vapor sorption of thermally modified Scots pine (Pinus sylvestris L.) wood. BioResources, 13(1), 331-345
Open this publication in new window or tab >>Effects of acid pre-treatments on the swelling and vapor sorption of thermally modified Scots pine (Pinus sylvestris L.) wood
2018 (English)In: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 13, no 1, p. 331-345Article in journal (Refereed) Published
Abstract [en]

Scots pine sapwood samples were pre-treated with a Lewis acid (AlCl3) and a combination of Lewis and protonic acids (AlCl3 and H2SO4), and were subsequently exposed to respective temperatures of 180 °C and 120 °C for establishing a comparable mass loss with those impregnated with demineralized water and solely thermally modified at 220 °C. Water impregnated samples dried at 120 °C also served as controls. The swelling behavior of all wood samples was examined with respect to maximum swelling in water, anti-swelling efficiency (ASE), shrinkage, and dynamic water vapor sorption at relative humidity ranges of 0% to 95%. The thermal modification at 220 °C diminished swelling and moisture adsorption, and also reduced moisture increment and decrement compared with the unmodified control. However, it was less obvious than both acid pre-treated samples. Excess surface work and Hailwood-Horrobin results calculated from water vapor sorption studies demonstrated that, at comparable mass loss, the available sorption sites were reduced to a greater extent by Lewis acid and combination of Lewis and protonic acids pre-treatment than the sole thermal treatment. This was attributed to more pronounced degradation of polysaccharides, mainly hemicelluloses and amorphous parts of cellulose, and to cross-linking of cell wall polymers due to the acid pre-treatments.

National Category
Wood Science Polymer Chemistry
Research subject
Technology (byts ev till Engineering), Forestry and Wood Technology
Identifiers
urn:nbn:se:lnu:diva-68862 (URN)10.15376/biores.13.1.331-345 (DOI)000427790000027 ()
Available from: 2017-11-20 Created: 2017-11-20 Last updated: 2019-03-19Bibliographically approved
Hemmilä, V., Zabka, M. & Adamopoulos, S. (2018). Evaluation of dynamic microchamber as a quick factory formaldehyde emission control method for industrial particleboards. Advances in Materials Science and Engineering, Article ID 4582383.
Open this publication in new window or tab >>Evaluation of dynamic microchamber as a quick factory formaldehyde emission control method for industrial particleboards
2018 (English)In: Advances in Materials Science and Engineering, ISSN 1687-8434, E-ISSN 1687-8442, article id 4582383Article in journal (Refereed) Published
Abstract [en]

The most common formaldehyde control method for wood panels in Europe, the perforator method, measures formaldehyde content, while most of the legal requirements in the world are based on emissions. Chamber methods typically used for emission measurements require too much time to reach steady state for factory quality control. The aim of this study was therefore to investigate whether emission values of particleboards measured one day after production would be usable for quality control purposes. The correlation between 1-day and 7-day emission values was determined using a dynamic microchamber (DMC). Three industrial board types that differed in density and emission levels were used for the evaluation. The online emission measuring equipment Aero-laser AL4021 connected to the 1 m3 chamber was used to gain further information on the emission reduction behaviour of the different board types. Only the two particleboard types with higher densities showed good correlation between the 1-day and 7-day emissions. The overall results suggested that 1-day emission values can be used for factory quality control purposes; however, if the initial 1-day values are above the permitted level, extensive evaluation for each individual board type needs to be performed

Place, publisher, year, edition, pages
Hindawi Publishing Corporation, 2018
National Category
Wood Science Other Chemical Engineering
Research subject
Technology (byts ev till Engineering), Forestry and Wood Technology
Identifiers
urn:nbn:se:lnu:diva-75901 (URN)10.1155/2018/4582383 (DOI)000436291600001 ()
Available from: 2018-06-14 Created: 2018-06-14 Last updated: 2019-03-19Bibliographically approved
van Blokland, J., Adamopoulos, S., Olsson, A., Oscarsson, J. & Källander, B. (2018). Evaluation of non-destructive test methods to predict bending properties of thermally modified timber. In: 2018 World Conference on Timber Engineering (WCTE),August 20-23, 2018, Seoul, Republic of Korea: . Paper presented at 2018 World Conference on Timber Engineering (WCTE),August 20-23, 2018, Seoul, Republic of Korea (pp. 8). National Institute of Forest Science (NIFoS)
Open this publication in new window or tab >>Evaluation of non-destructive test methods to predict bending properties of thermally modified timber
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2018 (English)In: 2018 World Conference on Timber Engineering (WCTE),August 20-23, 2018, Seoul, Republic of Korea, National Institute of Forest Science (NIFoS) , 2018, p. 8-Conference paper, Published paper (Refereed)
Abstract [en]

Thermally modified wood is available through a number of manufacturers in Europe on today’s market for interior and exterior building products. Thermal modification of wood allows for improvement of dimensional stability and durability, but a considerable decrease in strength properties occurs. Despite this loss in strength, thermally modified wood shows potential to be further exploited in structures exposed to loading. For such applications, accurate prediction of its static bending behaviour is essential. This paper studies the applicability of two different non-destructive test (NDT) techniques in estimating the bending properties of thermally modified timber (TMT). The study was done on 100 Norway spruce logs. One hundred (100) boards (i.e. one from each log) were thermally modified and the mirrored 100 boards were used as controls. After modification, resonance-based and time-of-flight measurements of axial wave velocity were carried out. Subsequently, all 200 boards were bent to failure following European standard EN408. This study shows that although TMT has a lower bending strength than unmodified timber, predictions of bending strength and stiffness using the NDT techniques are possible and with sufficient accuracy. The resonance-based method gave better predictions of the bending properties of TMT in respect to time-of-flight method.

Place, publisher, year, edition, pages
National Institute of Forest Science (NIFoS), 2018
Keywords
ThermoWood®, resonance method, time-of-flight method, four-point bending, Norway spruce
National Category
Wood Science Building Technologies
Research subject
Technology (byts ev till Engineering), Forestry and Wood Technology
Identifiers
urn:nbn:se:lnu:diva-77976 (URN)
Conference
2018 World Conference on Timber Engineering (WCTE),August 20-23, 2018, Seoul, Republic of Korea
Note

Ej belagd 181022

Available from: 2018-09-24 Created: 2018-09-24 Last updated: 2019-03-18Bibliographically approved
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ORCID iD: ORCID iD iconorcid.org/0000-0002-6909-2025

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