| 1. |
- Jiang, Wen, et al.
(författare)
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Particleboards with partially liquefied bark of different sizes
- 2019
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Ingår i: 3rd International Scientific Conference “Wood-Science-Economy”, 21-22 October, Poznan, Poland. - Poznan : ACSmedia Pracownia Reklamy. ; , s. 30-30
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Konferensbidrag (refereegranskat)abstract
- Utilizing biomass waste for wood-based composites has been driven by harsh competition for raw materials and environmental concerns for more sustainable products. Bark, as a by-product of the sawmilling and pulping industries, is a lignocellulosic material that is rich in lignin and extractives, and holds potential for producing chemicals and value-added materials. There are many possibilities of using bark in wood-based panel manufacturing such as making adhesives (e.g. bark tannin extractives, liquefied bark) or using it as a furnish in small amounts. Instead of using the completed liquefied bark products in the adhesive mixture, we have been working on a novel method of making particleboards by using partially liquefied bark as a furnish material with binding abilities. Thus, partially liquefied bark was mixed with wood chips with an aim to investigate the effect of different bark sizes on the properties of particleboards.Maritime pine (Pinus pinaster Ait.) bark was partially liquefied in the presence of ethylene glycol as solvent and sulphuric acid (H2SO4) as catalyst in 180˚C for 30 minutes. Four different sizes of bark were used: mix, coarse (> 2 mm), middle (1-2 mm), and fines (< 1 mm). One-layered 8-mm particleboards were prepared by mixing dry wood chips with the partially liquefied bark categories (9.1% or 20% w/w). Melamine-urea-formaldehyde (MUF) resin was 10% of the total weight of the furnish materials (dry wood chips and partially liquefied bark); while boards were also made without adding the resin. Mechanical and physical properties of the particleboards were tested according to the European standards, and ANOVA analysis of the results showed no statistically significant differences between varying bark sizes. Particleboards made with 9.1% of partially liquefied bark and with 10% of MUF resin met all the standard requirements for mechanical strength and thickness swelling. Particleboards made with 20% of partially liquefied bark and without adding MUF resin were inferior to those with MUF resin.From the current results we can conclude that it is possible to make particleboards from partially liquefied bark with competitive properties, and this supports our original idea of not completing the liquefaction process. In that respect, our work can contribute to energy and material savings when using liquefied products in wood panel manufacturing. More research is needed to optimize the process as well as to evaluate the formaldehyde emission level from this type of panels.
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| 2. |
- Hosseinpourpia, Reza, 1983-, et al.
(författare)
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Modification of Pea Starch and Dextrin Polymers with Isocyanate Functional Groups
- 2018
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Ingår i: Polymers. - : MDPI. - 2073-4360. ; 10:9
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Tidskriftsartikel (refereegranskat)abstract
- Pea starch and dextrin polymers were modified through the unequal reactivity of isocyanate groups in isophorone diisocyanate (IPDI) monomer. The presence of both urethane and isocyanate functionalities in starch and dextrin after modification were confirmed by Fourier transform infrared spectroscopy (FTIR) and 13C nuclear magnetic resonance (13C NMR). The degree of substitution (DS) was calculated using elemental analysis data and showed higher DS values in modified dextrin than modified starch. The onsets of thermal degradation and temperatures at maximum mass losses were improved after modification of both starch and dextrin polymers compared to unmodified ones. Glass transition temperatures (Tg) of modified starch and dextrin were lower than unmodified control ones, and this was more pronounced in modified dextrin at a high molar ratio. Dynamic water vapor sorption of starch and dextrin polymers indicated a slight reduction in moisture sorption of modified starch, but considerably lower moisture sorption in modified dextrin as compared to that of unmodified ones.
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| 3. |
- Foti, Dafni, et al.
(författare)
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Microstructure and compressive strength of gypsum-bonded composites with papers, paperboards and Tetra Pak recycled materials
- 2019
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Ingår i: Journal of Wood Science. - : Springer. - 1435-0211 .- 1611-4663. ; 65:1, s. 1-8
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Tidskriftsartikel (refereegranskat)abstract
- The incorporation of recycled papers, paperboards and Tetra Pak as filling materials in brittle matrices presents aninteresting approach in the utilization of waste materials for building construction. This paper examines the compressivestrength and microstructure of gypsum-bonded wastepaper-based composites. Recycled wastepaper of varioustypes (office paper, magazine paper and newspaper), cardboards, paper boxes and Tetra Pak were shredded to shortlength strips of about 4 × 18 mm. The shredded materials were used as filling materials in natural gypsum in a ratioof 1:3 (v/v), and water was added to the mix. The paste was formed in cylindrical samples measuring 10 cm in lengthand 5 cm in diameter. Seven different types of composites were produced depending on the material used. Thecomposite products with newspaper and magazine paper had significantly lower density and compressive strength(p < 0.05) than the others. However, the differences were small to have any practical importance. The density valuesranged between 1.26 and 1.34 g/cm3, and compressive strength was the lowest (4.48 N/mm2) in the gypsum–magazinepaper composites and the highest (6.46 N/mm2) in the gypsum–Tetra Pak I composites. Since the samplesproduced in this study exhibited adequate compressive strength, the products could be suitable for such applicationsas interior walls in building constructions. Scanning electron microscopy (SEM) examination of the fractured surfacesrevealed needle-like structures of gypsite crystals surrounding the fibers, which indicates good adhesion between thehydrophobic matrix and lignocellulosic fibers.
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| 4. |
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| 5. |
- Adamopoulos, Stergios, et al.
(författare)
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Acoustic properties of acetylated wood under different humid conditions and its relevance for musical instruments
- 2018
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Ingår i: Proceedings of the 9th European Conference on Wood Modification 2018, Arnhem, The Netherlands. - The Netherlands : Practicum. ; , s. 236-243
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Konferensbidrag (refereegranskat)abstract
- 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.
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| 6. |
- Adamopoulos, Stergios
(författare)
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Group of Forest Products
- 2018
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Ingår i: Presented at Symposium "Perspectives in Renewables", 4-5 June 2018, BOKU Vienna, Austria.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)
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| 7. |
- Adamopoulos, Stergios, et al.
(författare)
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Manufacturing and properties of gypsum-based products with recovered wood and rubber materials
- 2015
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Ingår i: BioResources. - : BioResources. - 1930-2126. ; 10:3, s. 5573-5585
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Tidskriftsartikel (refereegranskat)abstract
- The experimental production of gypsum-based products (cylindrical samples, solid bricks) using different fractions of wood chips and rubber particles was studied. Recovered rubber and wood materials were mixed with gypsum and water in various proportions to fabricate gypsum-wood and gypsum-rubber cylindrical samples and standard solid bricks with six holes using appropriate molds. It was shown that to manufacture gypsum-wood and gypsum-rubber products with good mechanical strength, coarse fractions of wood and rubber should be used, but the proportion of wood or rubber should not exceed 25%. No thermal conductivity differences were found between the wood-and rubber-type of gypsum products, and particle size and material proportion had no effect. Samples with fine wood and rubber particles present at a lower proportion (25%) exhibited similar sound absorption behavior. The solid bricks had slightly higher strength when loaded at the large surface of their lateral upper side than when loaded at the small surface. The bricks provided better thermal insulation than both the extruded and pressed house bricks but lower than that of insulating bricks. The emission of volatile organic compounds out of the bricks was at an acceptable level according to regulations for construction products.
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| 8. |
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| 9. |
- Adamopoulos, Stergios, et al.
(författare)
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Tensile strength of handsheets prepared with macerated fibres from solid wood modified with cross-linking agents
- 2015
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Ingår i: Holzforschung. - : Walter de Gruyter. - 0018-3830 .- 1437-434X. ; 69:8, s. 959-966
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Tidskriftsartikel (refereegranskat)abstract
- This study was conducted to explain the tensile strength loss of wood due to the modification with 1,3-dimethylol-4,5-dihydroxyethyleneurea (DMDHEU) and glutaraldehyde (GA). Modified and control wood blocks were macerated to deliberate fibres, and handsheets were produced thereof. The nitrogen content of the fibres indicated that maceration removed the major proportions of DMDHEU. The stability of GA in wood during maceration was not assessed. Tensile strength determined at zero span (z-strength) and finite span (f-strength) was equal for the handsheets from DMDHEU-modified fibres and the control handsheets. The microscopic appearance of the tested finite-span paper strips from DMDHEU-modified fibres mainly indicated interfibre failure and did not differ from the fibre fracture mode of the control handsheets. In contrast, the z-strength of the handsheets from GA-modified fibres was lower than that of controls and decreased with increasing content of GA in the initial modified wood. The f-strength behaviour of the handsheets from GA-modified fibres was the opposite: it was higher than that of controls and increased with increasing GA content. The microscopic appearance of the rapture zones of the finite-span testing mainly indicated intrafibre failure for the GA-modified fibres. It was concluded that cross-linking is likely to be the major reason for tensile strength loss of GA- and DMDHEU-modified wood. In terms of DMDHEU-modified wood, the incrustation of the cell wall by the resin and the reduction in pliability could play an additional role.
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| 10. |
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