| 1. |
- Ali, Alexandre Charifo, et al.
(författare)
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Comparative natural durability of five wood species from Mozambique
- 2011
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Ingår i: International Biodeterioration and Biodegradation. - : Elsevier BV. - 0964-8305. ; 65, s. 768-776
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Tidskriftsartikel (refereegranskat)abstract
- The objective of this study was to evaluate the natural durability of five lesser-utilized wood species from Mozambique. Both laboratory methods and field tests were applied for assessing wood decay of muanga (Pericopsis angolensis), metil (Sterculia appendiculata), namuno (Acacia nigrescens), ncurri (lcuria dunensis), and ntholo (Pseudolachnostylis maprounaefolia). Laboratory tests involved soft-, brown-, and white-rot fungi and termites. Heart- and sapwood of ncurri and ntholo were exposed in above-ground field tests; additionally, all species were exposed to in-ground contact tests. The results indicated that namuno, muanga, ncurri, and ntholo are resistant to soft-, brown- and white-rot fungi and the termite species Reticulitermes grassea and Mastotermes darwiniensis. Comparatively, soft-rot caused more severe decay on the studied wood species than did basidiomycete fungi. The brown-rot fungi Coniophora puteana, Gloeophiyllum trabeum, and Postia placenta caused less decay on the tested species than did the white-rot Trametes versicolor. Metil was not resistant to any of the mentioned hazards. Therefore, this species is not recommendable for exterior use if untreated. (C) 2011 Elsevier Ltd. All rights reserved.
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| 2. |
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| 3. |
- Cai, Shengzhen, et al.
(författare)
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Curing of wood treated with vinyl acetate-epoxidized linseed oil copolymer (VAc-ELO)
- 2016
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Ingår i: Holzforschung. - : Walter de Gruyter GmbH. - 0018-3830 .- 1437-434X. ; 70, s. 305-312
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Tidskriftsartikel (refereegranskat)abstract
- Scots pine sapwood was treated with a new formulation consisting of vinyl acetate (VAc) and epoxidized linseed oil (ELO) catalyzed by potassium persulfate to impart protection to wood. The effects of various curing temperatures, durations, and solution uptakes on dimensional stability (DS) and leachability were studied. The new formulation provided good anti-swelling efficiency (ASE) ranging from 35% to 47% with negligible leaching of the treating agent after four cycles of water soaking and oven drying (2%-2.5%). The extent of polymerization in wood was observed by FTIR-attenuated total reflectance (FTIR-ATR) by evaluation of the areas below typical IR bands as a function of curing temperature and time. Linear relationships were found with high R-2 values. The FTIR data of extracted samples were interpreted that chemical reactions took place between the resulting copolymer and wood components.
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| 4. |
- Cai, Shengzhen, et al.
(författare)
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Mechanical properties and decay resistance of Scots pine (Pinus sylvestris L.) sapwood modified by vinyl acetate-epoxidized linseed oil copolymer
- 2016
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Ingår i: Holzforschung. - : Walter de Gruyter GmbH. - 0018-3830 .- 1437-434X. ; 70, s. 885-894
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Tidskriftsartikel (refereegranskat)abstract
- Equilibrium moisture content (EMC), mechanical properties, and durability of Scots pine (Pinus sylvestris L.) sapwood modified by vinyl acetate epoxidized linseed oil (WVA-ELO) have been studied. Microscopic observations revealed that the impregnated copolymer is mainly in cell walls, rays, resin canals, and a small fraction in the cell lumens. Under the same climate conditioning, the EMC of the treated wood was in the range of 6.0%-8.2%, which was significantly lower than that of untreated wood (about 12%). Mechanical tests performed on paired samples (control and treated) showed a slight reduction on the mechanical properties of WVA-ELO. The decay resistance against basidiomycete fungi of WVA-ELO was significantly improved as demonstrated by laboratory tests. It was found that 8% weight percentage gain (WPG) was sufficient to ensure decay resistance against the test fungi with <5% mass loss (ML), which led to durability class (DC) of 2.
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| 5. |
- Cai, Shengzhen, et al.
(författare)
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Properties of epoxidised linseed oil-furfuryl alcohol and vinyl acetate-furfuryl alcohol treated wood
- 2014
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Furfurylation process is a well-studied wood modification method. Properties such as dimensional stability, decay resistance, moisture uptake and weathering have been reported to be greatly improved after treatment. However, the main remaining challenge for this process lies in the negative impact on the mechanical properties, especially the hardness which increased significantly. This has a direct impact on the structural applications of the material. In this context, new formulations consisting of combinations of furfural alcohol (FA) mixed with epoxidised linseed oil (ELO) or vinyl acetate (VA) were prepared and impregnated into Scots pine sapwood and cured without any additional crosslinking agents. Maleic anhydride was used as catalyst for polymerisation. The impact of the treatments has been studied concerning the mechanical properties, dimensional stability and durability. The average WPGs obtained after impregnation with VA-FA and ELO-FA treatments were 37.4% and 59.7% for samples intended for dimensional stability and 40.5% and 26.4% for samples intended for mechanical tests. With the achieved WPGs, the dimensional stability was significantly improved reaching an ASE of 63.3% and 43.1% for VA-FA-treated and ELO-FA-treated samples respectively. Mass loss caused by basidiomycetes fungi was in the range between 2 to 4% for both treatments, while the untreated samples lost more than 30%. MOE was almost not affected by the treatments, while impact bending strength increased by 26% after the ELO-FA treatment and decreased by 30% after the VA-FA treatment. Brinell hardness increased only by 21% for ELO-FA treatment and 64% for VA-FA treatment. These results showed that the combination of ELO with FA could result in durable timber without significant negative effect on the mechanical properties. Moreover, no darkening of the ELO-FA samples was observed.
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| 6. |
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| 7. |
- Cuvilas, Carlos Alberto, et al.
(författare)
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The Characterization of Wood Species from Mozambique as a Fuel
- 2014
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Ingår i: Energy Sources, Part A. - : Informa UK Limited. - 1556-7036 .- 1556-7230. ; 36:8, s. 851-857
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Tidskriftsartikel (refereegranskat)abstract
- The efficient utilization of fuelwood as a source of energy is strongly dependent on the properties of the biomass. This study characterizes common hardwood species from Mozambique and evaluates their quality as a fuel. Disc samples, taken at breast height, from Afzelia quanzensis Welwn, Millettia stuhlmannii Taub, Pterocarpus angolensis DC, Sterculia appendiculata K. Schum, Pericopsis angolensis Meeuwen, Acacia nigrescens Oliv., Pseudolachostylis maprounaefolia Pax, and Icuria dunensis Wieringa, were collected from three provinces in Mozambique. Chemical and physical properties were analyzed. The raking of the species as fuel was performed using fuelwood value index. The higher heating value varied between 19.38 and 21.50 MJ/kg dry weight. The concentration of lignin ranged from 21.96 up to 36.69% weight dry basis (wt% d.b.), and ash free. All studied species showed very low concentrations of Si, S, and Cl. Ash content varied between 0.76-3.71 wt% (d.b.), while the basic density ranged from 536 to 1,111 k gm(-3). Heavy metals were also determined and their concentrations were below the values reported in the literature. The species Acacia nigrescens had the highest fuelwood value index and it was closely followed by Icuria dunensis and Millettia stuhlmannii. The worst ranked was Sterculia appendiculata.
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| 8. |
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| 9. |
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| 10. |
- Gao, Jie, et al.
(författare)
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Chemical and ultrastructural changes in compound middle lamella (CML) regions of softwoods thermally modified by the Termovuoto process
- 2014
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Ingår i: Holzforschung. - : Walter de Gruyter GmbH. - 0018-3830 .- 1437-434X. ; 68, s. 849-859
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Tidskriftsartikel (refereegranskat)abstract
- Silver fir and Norway spruce wood have been thermally modified (TMW) for 3-4 h at 160 degrees C, 180 degrees C, 200 degrees C, and 220 degrees C by means of the thermovacuum process (Termovuoto), and the ultrastructural and chemical changes in the compound middle lamella (CML), including the middle lamella cell corner (MLcc) regions (CMLcc), were investigated. Severe anatomical and histochemical changes were prominent above treatment temperatures of 200 degrees C; thus, woods treated at 220 degrees C for 4 h were in focus. Immunocytochemical studies showed that noncellulosic polysaccharides, such as pectin, xyloglucan, xylan, and mannan, were significantly degraded in CMLcc regions of TMWs. After treatment, the CMLcc regions were composed almost entirely of modified lignin with increased amounts of acidic groups. With cytochemical staining for lignin, many electron dense particulates were detected in the CMLcc regions of TMWs, indicating early degradation/alteration by the Termovuoto treatment.
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| 11. |
- Gao, Jie, et al.
(författare)
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Decay resistance of softwoods and hardwoods thermally modified by the Thermovouto type thermo-vacuum process to brown rot and white rot fungi
- 2016
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Ingår i: Holzforschung. - : Walter de Gruyter GmbH. - 0018-3830 .- 1437-434X. ; 70, s. 877-884
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Tidskriftsartikel (refereegranskat)abstract
- Softwoods (SW, spruce and fir) and hardwoods (HW, ash and beech) were thermally modified by the thermo-vacuum (Termovuoto) process for 3-4 h in the temperature range 160-220 degrees C (TMW160-220 degrees C) and their fungal durability were examined in soil-block tests with two brown rot (BR, Postia placenta, Gloeophyllum trabeum) and two white rot (WR, Pycnoporus sanguineus, Phlebia radiata) fungi. SW-TMW160-220 degrees C were exposed to P. placenta and P. sanguineus and HW-TMW190-220 degrees C to all fungal species. Considerable improvement (durability class 1-3) in decay resistance was only achieved for SW-and HW-TMW 220 degrees C. Thermal modification (TM) below 200 degrees C influenced decay resistance negatively in case of some fungal species applied for both SW and HW. Judged by the durability class, decay resistance was higher in HW- than in SW-TMW at high TM temperature. Behavior of TM differed significantly between ash (ring-porous HW) and beech (diffuse-porous HW). A comparison between results of soil-and agar-block tests on Termovouoto wood demonstrated that the influence of testing method in terms of assignment to durability classes is not significant.
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| 12. |
- Gao, Jie, et al.
(författare)
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Effect of thermal modification on the durability and decay patterns of hardwoods and softwoods exposed to soft rot fungi
- 2018
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Ingår i: International Biodeterioration and Biodegradation. - : Elsevier BV. - 0964-8305. ; 127, s. 35-45
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Tidskriftsartikel (refereegranskat)abstract
- The durability and decay patterns of thereto-vacuum (Terrnowoto process for 3-4 h at 160-220 degrees C) treated hardwoods (ash, beech) and softwoods (spruce, fir) TMWs exposed to three soft rot fungi (Chaetorniwn globoswn, Phialophom malorum, P. mutabilis) were investigated using the soil-block test, light- and electron microscopy. Monitoring of mass loss over 1 year indicated that soft rot fungi do not attack softwood TMWs as rapidly or as extensively as hardwood TMWs. Decay resistance progressively increased in hardwood TMWs with increase in temperature but was unclear/or varied in softwood TMWs depending on fungal/wood species, particularly at lower temperatures (160-180 degrees C). Soft- and hardwood TMWs showed a major increase in decay resistance at 200-220 degrees C and 210-220 degrees C, respectively. Light microscopy of decayed hardwood TMWs showed formation of typical soft rot Type-I cavities in fibres at lower temperatures (190-200 degrees C). However, cavities were significantly inhibited or delayed at higher temperatures (210-220 degrees C). Cavity formation in vessels and parenchyma cells were only observed in beech TMW treated at 190 degrees C or references, indicating higher resistance than fibres. Transmission electron microscopy of decayed ash TMW treated at 200 degrees C showed a radial-like distribution of electron dense materials in cavities and lack of fibrillar-like materials within degraded fibre walls, which differed from reference.
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| 13. |
- Gao, Jie, et al.
(författare)
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Evaluation of Wood Quality Traits in Salix viminalis Useful for Biofuels: Characterization and Method Development
- 2021
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Ingår i: Forests. - : MDPI AG. - 1999-4907. ; 12
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Tidskriftsartikel (refereegranskat)abstract
- Salix (willow) is a well-known coppice plant that has been used as a source for bioenergy for decades. With recent developments in changing from a fossil-based to a circular bioeconomy, greater interest has been orientated towards willow as a potential source of biomass for transport biofuels. This has created increasing interest for breeding strategies to produce interesting genotypic and phenotypic traits in different willow varieties. In the present study, 326 genetically distinct clones and several commercial varieties of S. viminalis were analyzed using complementary approaches including density, chemical, image, histochemical, and morphometric analyses. A systematic approach was adopted whereby the basal regions of harvested stems were separated and used in all studies to aid comparisons. Density analyses were performed on all clone individuals, and from the results, 20 individual plants representing 19 clones were selected for the more in-depth analyses (chemical, image analysis, histochemical, and morphometric). The absolute dry density of the clones selected varied between ca. 300 and 660 kg/m3 with less variation seen in the commercial S. viminalis varieties (ca. 450–520 kg/m3). Selected clones for chemical analysis showed the largest variation in glucose (47.3–60.1%; i.e., cellulose) and total sugar content, which ranged between ca. 61 and 77% and only ca. 16 and 22% for lignin. Image analyses of entire basal stem sections showed presence of tension wood in variable amounts (ca. 7–39%) with characteristic G-fibers containing cellulose-rich and non-lignified gelatinous layers. Several of the clones showing prominent tension wood also showed high glucose and total sugar content as well as low lignin levels. A morphometric approach using an optical fiber analyzer (OFA) for analyzing 1000 s (minimum 100,000 particles) of macerated fibers was evaluated as a convenient tool for determining the presence of tension wood in stem samples. Statistical analyses showed that for S. viminalis stems of the same density and thickness, the OFA approach could separate tension wood fibers from normal wood fibers by length but not fiber width. Results emphasized considerable variability between the clones in the physical and chemical approaches adopted, but that a common aspect for all clones was the occurrence of tension wood. Since tension wood with G-fibers and cellulose-rich G-layers represents an increased source of readily available non-recalcitrant cellulose for biofuels, S. viminalis breeding programs should be orientated towards determining factors for its enhancement.
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| 14. |
- Gao, Jie, et al.
(författare)
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The contribution of G-layer glucose in Salix clones for biofuels: comparative enzymatic and HPLC analysis of stem cross sections
- 2022
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Ingår i: Biotechnology for Biofuels and Bioproducts. - : Springer Science and Business Media LLC. - 2731-3654. ; 15
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Tidskriftsartikel (refereegranskat)abstract
- Background: Interest on the use of short rotation willow as a lignocellulose resource for liquid transport fuels has increased greatly over the last 10 years. Investigations have shown the advantages and potential of using Salix spp. for such fuels but have also emphasized the wide variations existing in the compositional structure between different species and genotypes in addition to their effects on overall yield. The present work studied the importance of tension wood (TW) as a readily available source of glucose in 2-year-old stems of four Salix clones (Tora, Bjorn, Jorr, Loden). Studies involved application of a novel approach whereby TW-glucose and residual sugars and lignin were quantified using stem cross sections with results correlated with HPLC analyses of milled wood. Compositional analyses were made for four points along stems and glucose derived from enzyme saccharification of TW gelatinous (G) layers (G-glucose), structural cell wall glucose (CW-glucose) remaining after saccharification and total glucose (T-glucose) determined both theoretically and from HPLC analyses. Comparisons were also made between presence of other characteristic sugars as well as acid-soluble and -insoluble lignin.Results: Preliminary studies showed good agreement between using stem serial sections and milled powder from Salix stems for determining total sugar and lignin. Therefore, sections were used throughout the work. HPLC determination of T-glucose in Salix clones varied between 47.1 and 52.8%, showing a trend for higher T-glucose with increasing height (Bjorn, Tora and Jorr). Using histochemical/microscopy and image analysis, Tora (24.2%) and Bjorn (28.2%) showed greater volumes of % TW than Jorr (15.5%) and Loden (14.0%). Total G-glucose with enzyme saccharification of TW G-layers varied between 3.7 and 14.7% increasing as the total TW volume increased. CW-glucose measured after enzyme saccharification showed mean values of 41.9-49.1%. Total lignin between and within clones showed small differences with mean variations of 22.4-22.8% before and 22.4-24.3% after enzyme saccharification. Calculated theoretical and quantified values for CW-glucose at different heights for clones were similar with strong correlation: T-glucose = G-glucose + CW-glucose. Pearson's correlation displayed a strong and positive correlation between T-glucose and G-glucose, % TW and stem height, and between G-glucose with % TW and stem height.Conclusions: The use of stem cross sections to estimate TW together with enzyme saccharification represents a viable approach for determining freely available G-glucose from TW allowing comparisons between Salix clones. Using stem sections provides for discrete morphological/compositional tissue comparisons between clones with results consistent with traditional wet chemical analysis approaches where entire stems are milled and analyzed. The four clones showed variable TW and presence of total % G-glucose in the order Bjorn > Tora > Jorr > Loden. Calculated in terms of 1 m(3), Salix stems Tora and Bjorn would contain ca. 0.24 and 0.28 m(3) of tension wood representing a significant amount of freely available glucose.[GRAPHICS].
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| 15. |
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| 16. |
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| 17. |
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| 18. |
- Jebrane, Mohamed, et al.
(författare)
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Comparative Study of Two Softwood Species Industrially Modified by Thermowood (R) and Thermo-Vacuum Process
- 2018
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Ingår i: Bioresources. - : BioResources. - 1930-2126. ; 13, s. 715-728
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Tidskriftsartikel (refereegranskat)abstract
- Scots pine and Norway spruce, the most used commercial wood species in Europe, were thermally treated under industrial conditions by steam (Thermowood (R)) and vacuum (Termovuoto). Matched boards were treated, and the alterations in chemistry, color, mass loss, mechanical properties, and durability were compared. In treatments at identical temperature and duration, Thermowood (R) and the thermo-vacuum process caused similar mass loss in both wood species. The thermal treatments showed minor effects on the released acetic acid during the thermal degradation of polysaccharides. The equilibrium moisture content correlated well with the mass loss and confirmed indirectly the similarity of the two processes. The chemical composition and durability of the two groups of treated wood were similar. In conclusion, Thermowood (R) and thermo-vacuum treatments according to Termovuoto technology both produce similar final products with regard to chemical composition, physical-mechanical properties, and durability, with some differences in the appearance.
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| 19. |
- Jebrane, Mohamed, et al.
(författare)
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Comparative Wood Anatomy and Chemical Composition of Millettia mossambicensis and Millettia stuhlmannii from Mozambique
- 2018
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Ingår i: Bioresources. - : BioResources. - 1930-2126. ; 13, s. 3335-3345
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Tidskriftsartikel (refereegranskat)abstract
- The wood anatomy and chemistry of a relatively lesser used wood species, known in Mozambique as nsangala (Millettia mossambicensis J. B. Gillett), was compared to overexploited species jambire (Milletia stuhlmannii Taub.) to provide diagnostic features for safe discrimination. The anatomical results showed that both species shared several similarities such as intervessel pitting size range (8 mu m to 11 mu m), rays composed of only procumbent cells, fiber dimensions (average length up to 1359 mu m and wall thickness up to 10 mu m), and banded axial parenchyma. The extractives and lignin content were higher in jambire, while the carbohydrates and acetyl contents were higher in nsangala. The main anatomical feature separating the two species was the porosity pattern with semi-ring porous wood of nsangala compared to the diffuse-porous structure of jambire. Jambire had wider vessel lumina (200 mu m) and up to 3 vessels/mm(2) compared to nsangala vessel lumina of 86 mu m and a frequency of 37 vessels/mm(2).
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| 20. |
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| 21. |
- Jebrane, Mohamed, et al.
(författare)
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Dimensional stability and mechanical properties of exoxidized vegetable oils as wood preservatives
- 2016
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- In recent years, some vegetable oils such as linseed oil and soybean oil, have been used to preserve wood material, and contain no environmentally hazardous chemicals or chemicals harmful to humans. However, based on early studies related to vegetable oils, it was found that vegetable oils do not chemically bond with the wood structure, but rather only fill the cavities in the wood structure. This acts only to prevent the water uptake into wood. Because vegetable oils only act as a barrier to prevent water absorption, higher oil retentions (400 kg/m3 - 600 kg/m3) which are not cost-effective, would be needed to be effective in protecting wood. In this study, to reactivate oil and improve the bonding ability between oil and wood components, epoxidation of vegetable oil was targeted. Thus, more cost-effective oil retention levels between 80 kg/m3 and 270 kg/m3 were used due to treat the wood. With epoxidized vegetable oils, oil acids are able to bond to sites normally occupied by water molecules. This study also aimed to reduce leaching of boron compounds.
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| 22. |
- Jebrane, Mohamed, et al.
(författare)
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Enzymatic hydrolysis of the gelatinous layer in tension wood of Salix varieties as a measure of accessible cellulose for biofuels
- 2021
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Ingår i: Biotechnology for Biofuels. - : Springer Science and Business Media LLC. - 1754-6834. ; 14
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Tidskriftsartikel (refereegranskat)abstract
- Background: Salix (willow) species represent an important source of bioenergy and ofer great potential for producing biofuels. Salix spp. like many hardwoods, produce tension wood (TW) characterized by special fbres (G-fbres) that produce a cellulose-rich lignin-free gelatinous (G) layer on the inner fbre cell wall. Presence of increased amounts of TW and G-fbres represents an increased source of cellulose. In the present study, the presence of TW in whole stems of diferent Salix varieties was characterized (i.e., physical measurements, histochemistry, image analysis, and microscopy) as a possible marker for the availability of freely available cellulose and potential for releasing d-glucose. Stem cross sections from diferent Salix varieties (Tora, Björn) were characterized for TW, and subjected to cellulase hydrolysis with the free d-glucose produced determined using a glucose oxidase/peroxidase (GOPOD) assay. Efect of cellulase on the cross sections and progressive hydrolysis of the G-layer was followed using light microscopy after staining and scanning electron microscopy (SEM). Results: Tension wood fbres with G-layers were developed multilaterally in all stems studied. Salix TW from varieties Tora and Björn showed fbre G-layers were non-lignifed with variable thickness. Results showed: (i) Diferences in total % TW at diferent stem heights; (ii) that using a 3-day incubation period at 50 °C, the G-layers could be hydrolyzed with no apparent ultrastructural efects on lignifed secondary cell wall layers and middle lamellae of other cell elements; and (iii) that by correlating the amount of d-glucose produced from cross sections at diferent stem heights together with total % TW and density, an estimate of the total free d-glucose in stems can be derived and compared between varieties. These values were used together with a literature value (45%) for estimating the contribution played by G-layer cellulose to the total cellulose content. Conclusions: The stem section-enzyme method developed provides a viable approach to compare diferent Salix varieties ability to produce TW and thus freely available d-glucose for fermentation and biofuel production. The use of Salix stem cross sections rather than comminuted biomass allows direct correlation between tissue- and cell types with d-glucose release. Results allowed correlation between % TW in cross sections and entire Salix stems with d-glucose production from digested G-layers. Results further emphasize the importance of TW and G-fbre cellulose as an important marker for enhanced d-glucose release in Salix varieties.
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| 23. |
- Jebrane, Mohamed, et al.
(författare)
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Micro-distribution, Water Absorption, and Dimensional Stability of Wood Treated with Epoxidized Plant Oils
- 2018
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Ingår i: Bioresources. - 1930-2126. ; 13, s. 5124-5138
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Tidskriftsartikel (refereegranskat)abstract
- Samples of Scotch pine sapwood were treated with epoxidized linseed and soybean oils via an empty cell process to improve the hydrophobic properties of wood. Boric acid was included to introduce fungicidal properties into the oils. Two retention levels (80 to 140 kg/m(3) and 170 to 270 kg/m(3)) were targeted for oil treatments. Both an empty cell method and emulsion techniques were used to combine epoxidized oils and boric acid in a one-step treatment. Iodine number changes, Fourier transform infrared spectroscopy (FTIR), water absorption (WA), anti-swelling efficiency (ASE), and scanning electronic microscopy (SEM) analyses were used to characterize the wood after treatment. High iodine number changes that indicated a reduction the amount of unsaturated double bonds were determined. The FTIR analysis of epoxidized oils revealed a peak at 820 cm(-1), which indicated that epoxide moieties (C-O-C) were present. All of the oil treatments resulted in statistically significant lower water absorptions than the control sample. The lowest water absorption values were obtained from wood treated with epoxidized oils. The highest ASE result (70%) was observed on samples treated with epoxidized soybean oil at low retention (108 kg/m(3)). It was also determined that most of the latewood tracheids were filled with oils when compared to the earlywood tracheids.
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| 24. |
- Jebrane, Mohamed, et al.
(författare)
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Natural durability of selected larch and Scots pine heartwoods in laboratory and field tests
- 2014
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Ingår i: International Biodeterioration and Biodegradation. - : Elsevier BV. - 0964-8305. ; 91, s. 88-96
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to compare natural durability of Siberian larch heartwood grown in Siberia and Sweden as well as European larch and Scots pine heartwood grown in Sweden. The study was based on standard in- and above ground tests lasting 12 years but laboratory decay tests with white and brown rot fungi was also included. Field test results showed that Siberian larch heartwood from Siberia was the most durable among the studied heartwoods with a decay index of 60 after 12 years in Simlangsdalen (Sweden), while European larch heartwood grown in Sweden, was decayed to failure before the end of the test. Scots pine heartwood was found to perform similarly to Siberian larch from Siberia. No relationship could be established between natural durability of examined heartwoods and their water absorption behavior; however, strong correlation to the total amount of extractives was observed. Scots pine and Siberian larch heartwood from Siberia had 12.7 and 19.6% total extractives content respectively but the extractives composition differs. The study revealed also that lignin and monosaccharide content could not explain the variations in decay resistance of the studied heartwoods. No similarities in the natural durability revealed by laboratory and field tests were observed.
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| 25. |
- Jebrane, Mohamed, et al.
(författare)
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Natural Weathering and Photostability of Wood Modified by Fatty Acid Esters
- 2018
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Konferensbidrag (refereegranskat)abstract
- Polyunsaturated fatty acid vinyl ester was synthesized via a transition-metal catalyzed transvinylation reaction between vinyl acetate and fatty acids from Tung oil. The ensuing fatty acid vinyl ester (vinyl α-eleostearate) was characterized by FTIR and NMR spectral analyses and used as reactive reagent for modification of wood veneers. The covalent grafting of polyunsaturated fatty acid moieties onto the wood was achieved through transesterification reaction between wood hydroxyl groups and fatty acid vinyl ester. The transesterification reaction was confirmed by FTIR, 13C CP MAS NMR spectroscopy and the level of modification was estimated by determining the weight percentage gain (WPG). The photostability of modified wood veneers was evaluated by exposing wood veneers to natural weathering in Uppsala (Sweden) during April-May 2018. Upon 5 weeks of exposure to natural weathering, unmodified wood showed quick color changes and degradation of lignin, while modification of wood vinyl α-eleostearate was very effective in suppressing light-induced color changes at wood surfaces.
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| 26. |
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| 27. |
- Jebrane, Mohamed, et al.
(författare)
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Novel hydrophobization of wood by epoxidized linseed oil. Part 1. Process description and anti-swelling efficiency of the treated wood
- 2015
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Ingår i: Holzforschung. - : Walter de Gruyter GmbH. - 0018-3830 .- 1437-434X. ; 69, s. 173-177
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Tidskriftsartikel (refereegranskat)abstract
- The known method of wood modification by epoxidized linseed oil (ELO) has a limiting practical application due to the rapid polymerization of ELO in the presence of acetic acid (AA) needed as a catalyst. The present study was designed to develop an alternative method by means of a two-step process to avoid the rapid polymerization. The treatment options were tested on Scots pine sapwood, with the dimensional stability (DS) of the treated samples in focus. The new method provided an anti-swelling efficiency (ASE) in the range of 40-57%, which was even better than the thermally modified (TM) reference samples with 40% ASE. The developed two-step process is a feasible and practical approach for ELO treatment of wood.
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| 28. |
- Jebrane, Mohamed, et al.
(författare)
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Novel hydrophobization of wood by epoxidized linseed oil. Part 2. Characterization by FTIR spectroscopy and SEM, and determination of mechanical properties and field test performance
- 2015
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Ingår i: Holzforschung. - : Walter de Gruyter GmbH. - 0018-3830 .- 1437-434X. ; 69, s. 179-186
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Tidskriftsartikel (refereegranskat)abstract
- Scots pine samples were impregnated with epoxidized linseed oil (ELO) by means of a two-step process, and the effect of treatments has been studied concerning the Fourier transform infrared (FTIR) spectra, mechanical properties, moisture uptake, and field test performance. FTIR analysis of ELO-treated samples revealed that part of the ELO epoxy reactive group was chemically bound to the hydroxyl groups of wood. ELO-treated samples have improved dimensional stability, while the mechanical properties were slightly reduced and the moisture uptake was significantly lowered. The field performance of lap joints treated with ELO (90 kg m(-3)) after 60 months' exposure showed great improvements in performance, as the average annual moisture content (MC) was maintained at the level of 19.3% compared to 34.6% for lap joints treated with linseed oil (LO). The lap-joint area was not stained, and less discoloration by staining fungi on the external surfaces was observed in ELO-treated samples compared to samples treated with LO.
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| 29. |
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| 30. |
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| 31. |
- Jebrane, Mohamed, et al.
(författare)
-
Synthesis and characterization of new vinyl acetate grafting onto epoxidized linseed oil in aqueous media
- 2015
-
Ingår i: Journal of Applied Polymer Science. - : Wiley. - 0021-8995 .- 1097-4628. ; 132:24
-
Tidskriftsartikel (refereegranskat)abstract
- Modified poly (vinyl acetate) copolymers with epoxidized linseed oil (ELO) as co-monomer have been prepared. The polymerization was performed in aqueous medium without any additional protective colloid in the presence of sodium persulfate as catalyst. The effect of vinyl acetate (VAc)/ELO feed ratio, reaction temperature, reaction time, and catalyst amount has been studied. FTIR spectroscopy showed that the reaction between ELO and VAc resulted in slight decrease and shift in ELO characteristic bands of oxirane groups; and new bands were detected in the copolymer spectra attributed to PVAc and ELO functional groups. Moreover, new signals attributable to the copolymer were observed in the H-1 NMR spectra ( 4.07 and 1.62 ppm) and in the C-13 NMR spectra ( 15.29 and 31.0 ppm). Analysis by differential scanning calorimetry (DSC) showed a single T-g for the copolymerization product of VAc and ELO and two T-g for the PVAc/ELO blend, indicating the chemical reaction between VAc and ELO.
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| 32. |
- Jebrane, Mohamed, et al.
(författare)
-
The reactivity of linseed and soybean oil with different epoxidation degree towards vinyl acetate and impact of the resulting copolymer on the wood durability
- 2017
-
Ingår i: eXPRESS Polymer Letters. - : Department of Polymer Engineering, Scientific Society of Mechanical Engineering. - 1788-618X. ; 11, s. 383-395
-
Tidskriftsartikel (refereegranskat)abstract
- Linseed (LO) and soybean oil (SO) were in-situ epoxidized with peracetic acid to produce different degree of epoxidized LO and epoxidized SO. For comparison purpose, commercial epoxidized linseed oil (ELO (R)) and epoxidized soybean oil (ESO (R)) were also included in the study. The effect of epoxidation degree on the copolymerization reaction between epoxidized oils and vinyl acetate (VAc) was investigated. Results showed that a copolymer can be formed between VAc and epoxidized LO with high epoxy content, while no reaction occurred between VAc and SO or its epoxidized derivatives. As the most reactive monomer among the studied oils, the epoxidized LO with highest epoxy content (i.e. ELO (R)) was mixed with VAc and then impregnated into the wood using three different ELO (R) /VAc formulations either as solution or as emulsions. After curing, the impact of the resulting copolymer issued from the three tested formulations on the wood durability was evaluated. Results showed that the formulation comprising VAc, ELO (R), H2O, K2S2O8 and alkaline emulsifier (Formulation 3) can significantly improve wood's durability against white rot- (Trametes versicolor) and brown rot fungi (Postia placenta and Coniophora puteana). Treated wood of 8% weight percentage gain (WPG) was sufficient to ensure decay resistance against the test fungi with less than 5% mass loss.
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| 33. |
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| 34. |
- Karunasekera, Hasanthi, et al.
(författare)
-
Does copper tolerance provide a competitive advantage for degrading copper treated wood by soft rot fungi?
- 2017
-
Ingår i: International Biodeterioration and Biodegradation. - : Elsevier BV. - 0964-8305. ; 117, s. 105-117
-
Tidskriftsartikel (refereegranskat)abstract
- The ability of soft rot fungi possessing strong (Phialophora malorum), medium (Phialophora mutabilis) and poor copper tolerance (Chaetomium globosum) to degrade untreated and CuSO4 and micronized copper treated birch- and pine wood was assessed using ENV 807 standard tests. The aim was to determine whether an ability to grow on Cu-agar and copper in liquid cultures can be transcribed into a competitive advantage to degrade Cu-treated wood. An ability to tolerate high copper levels in-vitro was not correlated with increased decay by the fungi but rather reflected the native chemistry of the wood cell walls. Both untreated and Cu-treated wood were degraded by the three fungi and showed aggressiveness in the order C. globosum > P.mutabilis > P.malorum. Higher mass loss was recorded for birch than pine and decreased progressively as the copper loadings increased with statistically insignificant difference noted between Cu-treatments. Microscopy showed decay at the cell wall level to reflect degree of lignification with parenchyma cells degraded first in both untreated and Cu-treated wood. Results indicate presence of copper and its toxicity is unlikely to be the main reason for preventing soft rot decay of wood but rather the additive effect of copper binding to the wood material.
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| 35. |
- Kim, Jongsik, et al.
(författare)
-
Chemical and ultrastructural changes of ash wood thermally modified using the thermo-vacuum process: I. Histo/cytochemical studies on changes in the structure and lignin chemistry
- 2015
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Ingår i: Holzforschung. - : Walter de Gruyter GmbH. - 0018-3830 .- 1437-434X. ; 69, s. 603-613
-
Tidskriftsartikel (refereegranskat)abstract
- Changes in structure and lignin chemistry were investigated in ash wood thermally modified (TMW) by the thermo-vacuum (Termovuoto) process for 3 h at 190-220 degrees C by means of light, fluorescence, and transmission electron (TEM) microscopy combined with histo/cytochemistry. Variation in changes in native cell color in TMWs was positively correlated with differences in lignin content between cell types and cell wall regions in the reference wood. Histochemical staining showed increasing amounts of acidic groups in TMWs with different response to ethanol extraction between secondary cell walls and CMLcc (compound middle lamella/middle lamella cell corner) regions. Fluorescence microscopy of TMWs and references showed a difference in intensity and color emission of lignin autofluorescence, reflecting modification of lignin in TMWs. Changes in histochemistry and fluorescence were prominent at and above 200 degrees C. With TEM, increased intensity of lignin staining and distortion of fiber S-1 layers were detected in TMW treated for 3 h at 220 degrees C (TMW3 h, 220 degrees C). TMW3 h, 220 degrees C differed significantly in molecular ultrastructure of fiber cell walls compared to references, such as loss of the lamellar structure and size and distribution of lignin aggregates. The modification in CMLcc structure in ash TMW3 h, 220 degrees C is different from that of softwoods.
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| 36. |
- Lhate, Inácio Arnaldo, et al.
(författare)
-
Chemical composition of traditionally and lesser used wood species from Mozambique
- 2010
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Ingår i: Wood Material Science and Engineering. - : Informa UK Limited. - 1748-0272 .- 1748-0280. ; 5, s. 143-150
-
Tidskriftsartikel (refereegranskat)abstract
- The main objective of this study was to determine the chemical composition of some lesser used Mozambican native wood species, such as Acacia nigrescens Oliv., Icuria dunensis Wieringa, Pseudolachnostylis maprounaefolia Pax and Sterculia appendiculata K. Schum. Another aim was to compare these species with traditionally used species, namely, Afzelia quanzensis Welwn, Milletia stuhlmannii Taub, Pericopsis angolensis Meeuwen and Pterocarpus angolensis DC. Wood samples for analysis were taken from sapwood, outer and inner heartwood. All chemical analyses were performed according to standard methods. The contents of carbohydrates, extractives and ash were in ranges considered normal for tropical species. The contents of lignin and minerals were unexpectedly high in Pseudolachnostylis (ntholo), reaching 37.51% and 2.2% (wt% extractive-free) on a dry basis, respectively. Based on the determined chemical features, it was concluded that Acacia and Pseudolachnostylis were similar to well-known species, whereas Icuria and Sterculia differed from the known species. Keywords: Acacia nigrescens; cellulose; extractives; hemicellulose; Icuria dunensis; Klason lignin; minerals content; Pseudolachnostylis maprounaefolia; Sterculia appendiculata
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| 37. |
- Nazari, Meysam, et al.
(författare)
-
Bio-based phase change material for enhanced building energy efficiency: A study of beech and thermally modified beech wood for wall structures
- 2024
-
Ingår i: Energy Storage. - 2578-4862. ; 6
-
Tidskriftsartikel (refereegranskat)abstract
- This study investigated the impregnation of beech and thermally modified beech (TMB) with a ternary mixture of capric acid, palmitic acid, and stearic acid as a bio-based phase change material (BPCM). Finite element method (FEM) was used to complement the experimental analysis by providing new insights into computational methods for simulating the behavior of BPCMs in untreated and TMB. The analyzed specimens namely beech and TMB were impregnated with BPCM; the TMB achieved 54% weight percentage gain (WPG) while untreated beech got 37%. Accordingly, a greater increase in the latent heat was obtained for TMB up to 90 J/g, while for untreated beech with BPCM up to 75 J/g. Impregnated specimens absorbed less moisture at relative humidity of air above 50%, likely caused by the high uptake and hydrophobic nature of the BPCM. The study highlights the research gap in performing mathematical simulations on wood samples with BPCM using material thermal properties derived from differential scanning calorimetry or T-History analysis. It shows that the direct use of these values for simulations leads to unacceptable outputs that result in high errors. The root mean square error for untreated and TMB samples impregnated with BPCM was in the range from 1.06 to 3.1 while that for untreated samples was in the range from 0.57 to 0.87, indicating that the main challenge in simulating and characterizing the samples is due to the interaction of the phase change material with the wood structure.
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| 38. |
- Nazari, Meysam, et al.
(författare)
-
Bio-Based Phase Change Materials for Wooden Building Applications
- 2022
-
Ingår i: Forests. - : MDPI AG. - 1999-4907. ; 13
-
Tidskriftsartikel (refereegranskat)abstract
- Solid wood can serve multifunctionality for energy savings in buildings. The study reveals the results of biodeterioration and degradation of solid Scots pine wood used to incorporate single or multicomponent fatty acid mixtures as bio-based phase change materials (BPCMs). The sapwood samples were impregnated with capric acid (CA), methyl palmitate (MP), lauryl alcohol (LA) and a mixture of coconut oil fatty acids and linoleic acid (CoFA-LA). The samples were tested against subterranean termites by an Italian species (Reticulitermes lucifugus), the wood boring beetle Hylotrupes bajulus and mold through a discoloration test. Tested against termites, the impregnated samples were significantly less susceptible to the attack than the controls, i.e., the tested BPCMs were resistant to R. lucifugus. The only test with MP terminated at the moment against H. bajulus showed positive results with no larvae surviving. The mold discoloration test revealed that the wood impregnated with CoFA-LA was identically susceptible to mold discoloration when compared to the control, nonimpregnated samples. This pioneer study verifies that solid wood employed for the encapsulation of BPCMs for building purposes can serve identically or somewhat better than similar wooden building elements regarding attacks of the above microorganisms and insects. Such multifunctional building elements will be tested further in a pilot scale building to characterize better the durability aspects of the new materials.
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| 39. |
- Nazari, Meysam, et al.
(författare)
-
Bio-Based Phase Change Materials Incorporated in Lignocellulose Matrix for Energy Storage in Buildings-A Review
- 2020
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Ingår i: Energies. - : MDPI AG. - 1996-1073. ; 13
-
Forskningsöversikt (refereegranskat)abstract
- Due to growing consciousness regarding the environmental impact of fossil-based and non-sustainable materials in construction and building applications, there have been an increasing interest in bio-based and degradable materials in this industry. Due to their excellent chemical and thermo-physical properties for thermal energy storage, bio-based phase change materials (BPCMs) have started to attract attention worldwide for low to medium temperature applications. The ready availability, renewability, and low carbon footprint of BPCMs make them suitable for a large spectrum of applications. Up to now, most of the BPCMs have been incorporated into inorganic matrices with only a few attempts to set the BPCMs into bio-matrices. The current paper is the first comprehensive review on BPCMs incorporation in wood and wood-based materials, as renewable and sustainable materials in buildings, to enhance the thermal mass in the environmentally-friendly buildings. In the paper, the aspects of choosing BPCMs, bio-based matrices, phase change mechanisms and their combination, interpretation of life cycle analyses, and the eventual challenges of using these materials are presented and discussed.
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| 40. |
- Nazari, Meysam, et al.
(författare)
-
Engineered Wood Material with Bio-Based Phase Change Material and Micronised Copper for Building Applications
- 2023
-
Ingår i: Pro Ligno. - 1841-4737 .- 2069-7430. ; 19, s. 91-95
-
Tidskriftsartikel (refereegranskat)abstract
- In this study, pine sapwood was first impregnated with micronized copper (Cu) solution at concentrations of 5 and 10%, the samples then dried and impregnated with ethyl palmitate as a bio-based phase change material (BPCM). The leakage test showed slightly less leakage in this scenario compare to controls without copper. The mould test showed using copper solution, significattly improves the resistance of the composites to mould growth. Thermal tests showed using BPCM improves thermal conductivity and thermal mass of the composites, enabling them to store and release energy within the temperature range of 20-25ºC. It is observed that the copper did not improve thermal conductivity, and 5% copper showed the best performance in thermal mass improvement.
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| 41. |
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| 42. |
- Nazari, Meysam, et al.
(författare)
-
Multicomponent bio-based fatty acids system as phase change material for low temperature energy storage
- 2021
-
Ingår i: Journal of Energy Storage. - : Elsevier BV. - 2352-152X. ; 39
-
Tidskriftsartikel (refereegranskat)abstract
- In this study, new multicomponent mixtures of fatty acids for low temperature thermal energy storage applications have been developed. The new mixtures were based on coconut oil fatty acids (CoFA) and commercial grades of oleic (OA) and linoleic acid (LA). Refined coconut oil (CO) was first converted into free fatty acids by alkaline saponification. The prepared CoFA were then mixed with OA or LA at various compositions to prepare stable bio-based phase change materials (BPCMs). The thermal behavior including melting/solidification temperatures, specific heat and enthalpy of the developed mixtures were investigated by means of differential scanning calorimetry (DSC) and T-history. Transient hot wire method was used to measure thermal conductivity of the PCMs. The chemical stability and thermal reliability of the mixtures were assessed stepwise from 100 to 700 melt/freeze cycles by attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR) and DSC. Based on DSC and T-history results, the phase transition of the developed PCMs were in line with the range of human comfort temperatures i.e. 18-25 degrees C, with no incongruent melting and less than 0.6 degrees C super cooling, whereas specific heat and enthalpy of the new mixtures were in the range of 1-5 J/g K, and 40-100 J/g. The FTIR and DSC results indicated that the PCMs mixtures are chemically and thermally stable. The thermal conductivity of the mixtures were in average 0.2 W/m K, in liquid phase and 0.35 W/m K, in solid phase. Out of the different developed combinations, the mixture of LA/CoFA (20/80) showed distinguished performance and can be considered as potential BPCM for low temperature thermal energy storage applications.
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| 43. |
- Nazari, Meysam, et al.
(författare)
-
New hybrid bio-composite based on epoxidized linseed oil and wood particles hosting ethyl palmitate for energy storage in buildings
- 2023
-
Ingår i: Energy. - 0360-5442 .- 1873-6785. ; 278
-
Tidskriftsartikel (refereegranskat)abstract
- In this study, the incorporation of ethyl palmitate (EP) as a bio-based phase change material (BPCM) in wood particles, the preparation and properties of the novel biocomposite for building applications were investigated. The wood particle-based composites hosting BPCM were produced by cold compression moulding. The EP impregnation step was optimized in terms of uptake and its ratio by post-addition of non-impregnated fibers. The optimized wood particles/EP ratio were combined with 37.5% epoxidized linseed oil (ELO) as a binder to produce a composite with energy storage function containing more than 99% bio-ingredients. The optimum BPCM content in the composite was 25%. The produced biocomposites were characterized by T-hystory, DSC, TGA, and a moisture buffer test. The results revealed excellent moisture buffer values (2.07 g/m2 RH%) according to the Nordtest protocol, significant thermal mass, ability to store excessive energy in terms of latent heat and maintain the temperature constant for longer time, good thermal stability and improved specific heat capacity when compared to a reference composite without BPCM. The effect of incorporating BPCM into biocomposite for regulating temperature fluctuations was confirmed by comparing test prototype cubes, with and without BPCM, subjected to temperature fluctuation between 0 and 40 ◦C.
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| 44. |
- Nazari, Meysam, et al.
(författare)
-
Solid wood impregnated with a bio-based phase change material for low temperature energy storage in building application
- 2022
-
Ingår i: Journal of Thermal Analysis and Calorimetry. - : Springer Science and Business Media LLC. - 1388-6150 .- 1588-2926. ; 147, s. 10677-10692
-
Tidskriftsartikel (refereegranskat)abstract
- Wood impregnated with a multicomponent mixture of fatty acids as a bio-based phase change material (BPCM) to improve its thermal characteristics was studied. The studied wood/BPCM composites can be used as internal elements in buildings for energy storage. Scots pine and beech sapwood were impregnated with a multicomponent mixture of linoleic acid and coconut oil fatty acids at a ratio of 20:80. Leakage test was conducted and revealed that the maximum leakage for pine and beech were 9 and 8%, respectively. Light microscopy was employed to demonstrate the distribution of the BPCM in the wood structure. Rays in both pine and beech wood served as pathways for impregnation of the BPCM to partly fill the tracheid lumens (pine) and vessels (beech). Thermal characterization of the studied samples employed T-history and DSC methods, concluding that the impregnated wood had significant thermal mass, ability to store excessive energy in terms of latent heat and keep the temperature constant for long time. The specific heat capacity of the impregnated samples was 4-5 J g(-1) K-1 i.e., higher than that of the untreated control samples of ca. 2 J g(-1) K-1. The thermal conductivity of the samples before and after the impregnation was measured using heat flow meter method and the results showed that the untreated beech wood had higher thermal conductivity compared to pine and the parameter improved when the cell lumens were filled with the BPCM. Scots pine wood with to 80% mass percentage gain (MPG) after impregnation demonstrated an increment in thermal conductivity of 33% while Scots pine and beech with 43 and 38% MPG demonstrated an increase of the conductivity with 8 and 11%, respectively.
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| 45. |
- Nazari, Meysam, et al.
(författare)
-
Thermal performance and mold discoloration of thermally modified wood containing bio-based phase change material for heat storage
- 2022
-
Ingår i: Energy Storage. - : Wiley. - 2578-4862. ; 4
-
Tidskriftsartikel (refereegranskat)abstract
- The work presents the results of thermal performance and mold discoloration of thermally modified wood-based composites incorporating multicomponent fatty acids as a bio-based phase change materials (BPCM). Thermally modified Scots pine (TMP), beech (TMB), and spruce (TMS) sapwood were impregnated with a multicomponent mixture of linoleic acid and coconut oil fatty acids at a ratio of 20:80. Samples with different BPCM uptakes were analyzed in the temperature range typical for building indoor conditions. Leakage tests were conducted and revealed that the maximum leakage for all the samples is 3% to 5%. T-history and heat flowmeter methods were used to evaluate the thermal characteristic of the composites. The incorporation of BPCM into thermally modified woods (TMWs) resulted in significant thermal mass improvements, expressed by the ability of the composites to store excessive energy in terms of latent heat and keep the temperature constant for long time. The specific heat capacity of the TMWs was around 2 J/g K, which increased to 4 to 8 J/g K after impregnation with BPCM, depending on the impregnation uptake. Results showed also that TMB has higher thermal conductivity than TMP and TMS, while incorporating of BPCM into these materials resulted in even improved thermal conductivity. Results showed that the thermal conductivity of TMP increased after incorporation of BPCM from 0.06 W/m K to 0.1 and 0.14 W/m K for TMP/BPCM with 48% and 95% uptake respectively. Mold tests showed that BPCM encapsulated in TMWs is less susceptible to mold discoloration compared to untreated wood.
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| 46. |
- Nazari, Meysam, et al.
(författare)
-
Wood Impregnated with a Multicomponent Bio-Phase Change Material for Energy Storage in Buildings
- 2021
-
Ingår i: Refrigeration science and technology. - 0151-1637. ; , s. 393-400
-
Konferensbidrag (refereegranskat)abstract
- Wood is widely used in buildings but its low thermal mass limits its energy efficiency for internal use. The thermal mass of wood can be improved by incorporation of PCMs into its porous structure, and thus can control energy intermittency inside buildings. In this study, coconut oil fatty acids mixed with linoleic acid in 4:1 (w/w), with a phase transition temperature in the range of human comfort (18-25 degrees C), were integrated into thermally treated spruce. The impregnation uptake was 60% and the stability of the PCM in wood structure was evaluated by subjecting impregnated wood samples to leaching tests, and found to be 5%. Thermal characteristics of the wood/BPCM composite including phase transition temperature, enthalpy, heat capacity and thermal conductivity were investigated with DSC, T-history and heat flow meter method, and respectively found to be in the range of 22.4-25.5 degrees C, 39 J/g, 4 J/(g K) and 0.13 W/(m K).
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| 47. |
- Nazari, Meysam, et al.
(författare)
-
Wood impregnated with multicomponent bio-based PCM for low temperature energy storage in buildings
- 2021
-
Ingår i: Refrigeration science and technology. - 0151-1637.
-
Konferensbidrag (refereegranskat)abstract
- Wood is widely used in buildings but its low thermal mass limits its energy efficiency for internal use. The thermal mass of wood can be improved by incorporation of PCMs into its porous structure, and thus can control energy intermittency inside buildings. In this study, coconut oil fatty acids mixed with linoleic acid in 4:1 (w/w), with a phase transition temperature in the range of human comfort (18-25 ºC), were integrated into thermally treated spruce. The impregnation uptake was 60% and the stability of the PCM in wood structure was evaluated by subjecting impregnated wood samples to leaching tests, and found to be 5%. Thermal characteristics of the wood/BPCM composite including phase transition temperature, enthalpy, heat capacity and thermal conductivity were investigated with DSC, T-history and heat flow meter method, and respectively found to be in the range of 22.4-25.5 °C, 39 J/g, 4 J/(g K) and 0.13 W/(m K).
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| 48. |
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| 49. |
- Pockrandt, Michael, et al.
(författare)
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Industrial Thermowood (R) and Termovuoto thermal modification of two hardwoods from Mozambique
- 2018
-
Ingår i: Holzforschung. - : Walter de Gruyter GmbH. - 0018-3830 .- 1437-434X. ; 72, s. 701-709
-
Tidskriftsartikel (refereegranskat)abstract
- The study aimed at treating metil (Sterculia appendiculata K. Schum) and neem (Azadirachta indica A. Juss) timber from Mozambique under industrial conditions by steam [Thermowood (R) (TW)] and vacuum [Termovuoto (TV)] thermal modifications (TM). Matched boards were treated identically and wood alterations in chemistry, colour, mass loss (ML), mechanical properties and durability were compared. The applied vacuum partly removed the acetic acid that causes carbohydrate degradation, i.e. heat applied under vacuum was less destructive. TM under vacuum generated a lighter colour than that caused by steam treatment. ML was significantly higher after the TW process namely, 14.1 vs. 9.9% after thermovacuum treatment for metil and 14.2 and 12.1% for neem. Colour and ML changes correlated with the decrease in shear strength, rupture and elasticity moduli and increase in wood decay resistance. Metil wood is more permeable and demonstrated significant differences between the treatments; the thereto-vacuum process was less destructive but led to less improvement of durability compared to TW treatment.
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| 50. |
- Råberg, Ulrika, et al.
(författare)
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Characterization of test fields
- 2013
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Ingår i: Proceedings IRG Annual Meeting. - 2000-8953.
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Test field characteristics and impact of test fields on wood degradation is important when testing wood protection. The current EN 252 standard has no requirement for knowledge of decay hazards, but most commonly a test field is known as a “brown”,- “white”,- or “soft rot” field. To understand which decay hazard wood preservatives are tested against, each test field should be characterized. Our purpose here is to outline a number of different approaches that we have been using to characterize four test fields belonging to the Department of Forest Products, SLU, Sweden. For characterization we isolated fungi from EN 252 Scots pine stakes by using different media and identified the isolated fungi by DNA sequencing. DNA profiles were established for Scots pine mini- stakes as well as microscopy characterization of stake cross sections for decay type and degree of attack. MOE and mass loss was measured for the mini-stakes at one test field. For all fields, the pick test of EN 252 stakes were performed according to the European Standard EN 252. A summary of problems and possibilities of the techniques are presented. Our results show that by combining different approaches like molecular techniques with microscopy and/or strength tests, it is possible to obtain good characterization of test fields, the inherent fungi, and their decay capacity cannot be described by using only one approach. Keywords: DNA sequencing, fungal isolation, microscopy, MOE, pick test, test field
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