Helena C. Quilter, Regis Risani, Suzanne Gallagher, Michael Robertson, Armin Thumm, Hayden P. Thomas, Robert Abbel
The bark of Pinus radiata offers an underutilized source of high-value renewable chemicals such as extractable polyphenols and lipophilic compounds (waxes and suberin). Here, the depolymerization and extraction of suberin from P. radiata bark and its repolymerization to form novel polyesters are reported. Three different strategies were evaluated for repolymerization of the suberin monomers, with starting materials and products characterized using chemical and thermal analysis techniques. The inclusion of comonomer (1,12-dodecanediol) to provide stoichiometric balance improved the conversion, product yield, solubility and increased molecular weight. Enzymatic polymerization conditions gave the highest yield, while the highest molecular weight was achieved using titanium butoxide, demonstrating that polymerization conditions could be varied to target desired product properties. Products were hydrophobic, as shown by contact angles, ϴ ≥ 90° after 30 s. This work highlights opportunities for utilizing suberin to add value to a P. radiata bark biorefinery concept. Potential future applications include its use as a starting material for novel bio-based polymers that can serve as water-repellent surfaces and coatings, replacing established products derived from fossil resources.
{"title":"Synthesis of hydrophobic biopolyesters from depolymerized Pinus radiata bark suberin","authors":"Helena C. Quilter, Regis Risani, Suzanne Gallagher, Michael Robertson, Armin Thumm, Hayden P. Thomas, Robert Abbel","doi":"10.1515/hf-2023-0104","DOIUrl":"https://doi.org/10.1515/hf-2023-0104","url":null,"abstract":"The bark of <jats:italic>Pinus radiata</jats:italic> offers an underutilized source of high-value renewable chemicals such as extractable polyphenols and lipophilic compounds (waxes and suberin). Here, the depolymerization and extraction of suberin from <jats:italic>P. radiata</jats:italic> bark and its repolymerization to form novel polyesters are reported. Three different strategies were evaluated for repolymerization of the suberin monomers, with starting materials and products characterized using chemical and thermal analysis techniques. The inclusion of comonomer (1,12-dodecanediol) to provide stoichiometric balance improved the conversion, product yield, solubility and increased molecular weight. Enzymatic polymerization conditions gave the highest yield, while the highest molecular weight was achieved using titanium butoxide, demonstrating that polymerization conditions could be varied to target desired product properties. Products were hydrophobic, as shown by contact angles, <jats:italic>ϴ</jats:italic> ≥ 90° after 30 s. This work highlights opportunities for utilizing suberin to add value to a <jats:italic>P. radiata</jats:italic> bark biorefinery concept. Potential future applications include its use as a starting material for novel bio-based polymers that can serve as water-repellent surfaces and coatings, replacing established products derived from fossil resources.","PeriodicalId":13083,"journal":{"name":"Holzforschung","volume":"37 1","pages":""},"PeriodicalIF":2.4,"publicationDate":"2024-03-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140105268","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Johannes Karthäuser, Andreas Treu, Erik Larnøy, Holger Militz, Gry Alfredsen
Phenol-formaldehyde (PF) resins can be impregnated and cured in situ to improve the woods dimensional stability and decay resistance. In search of renewable alternatives, the substitution of phenol by lignin cleavage products (LCP) has been discussed. However, the different chemical nature may affect the performance of the resin against fungal decay, formaldehyde emission, and equilibrium moisture content. In this study, 30 % (w/w) of the phenol in PF resins were substituted by LCP obtained from microwave-assisted pyrolysis. Scots pine sapwood was modified with the resin. The decay resistance against Rhodonia placenta, Gloeophyllum trabeum, and Trametes versicolor was determined. Additionally, effects of specimen organisation within the Petri dish, different substrates, length of leaching, and type of inoculum were studied. Further, the materials water vapor sorption properties and formaldehyde emission were determined. All modifications effectively reduced fungal decay. With 10 % weight percent gain (WPG), initial decay was detected, while 20 % WPG and 30 % WPG provided efficient protection. The substitution of phenol increases the formaldehyde emission. While further reduction in formaldehyde in the resin admixture or formaldehyde scavengers may be required, the method described herein can be used to partly replace fossil-based phenol, while maintaining good fungal resistance.
{"title":"Resistance against fungal decay of Scots pine sapwood modified with phenol-formaldehyde resins with substitution of phenol by lignin pyrolysis products","authors":"Johannes Karthäuser, Andreas Treu, Erik Larnøy, Holger Militz, Gry Alfredsen","doi":"10.1515/hf-2023-0119","DOIUrl":"https://doi.org/10.1515/hf-2023-0119","url":null,"abstract":"Phenol-formaldehyde (PF) resins can be impregnated and cured <jats:italic>in situ</jats:italic> to improve the woods dimensional stability and decay resistance. In search of renewable alternatives, the substitution of phenol by lignin cleavage products (LCP) has been discussed. However, the different chemical nature may affect the performance of the resin against fungal decay, formaldehyde emission, and equilibrium moisture content. In this study, 30 % (w/w) of the phenol in PF resins were substituted by LCP obtained from microwave-assisted pyrolysis. Scots pine sapwood was modified with the resin. The decay resistance against <jats:italic>Rhodonia placenta, Gloeophyllum trabeum</jats:italic>, and <jats:italic>Trametes versicolor</jats:italic> was determined. Additionally, effects of specimen organisation within the Petri dish, different substrates, length of leaching, and type of inoculum were studied. Further, the materials water vapor sorption properties and formaldehyde emission were determined. All modifications effectively reduced fungal decay. With 10 % weight percent gain (WPG), initial decay was detected, while 20 % WPG and 30 % WPG provided efficient protection. The substitution of phenol increases the formaldehyde emission. While further reduction in formaldehyde in the resin admixture or formaldehyde scavengers may be required, the method described herein can be used to partly replace fossil-based phenol, while maintaining good fungal resistance.","PeriodicalId":13083,"journal":{"name":"Holzforschung","volume":"37 1","pages":""},"PeriodicalIF":2.4,"publicationDate":"2024-03-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140074415","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Thi Tham Nguyen, Cong Chi Tran, Thi Vinh Khanh Nguyen, Trong Kien Nguyen, Zefang Xiao, Yanjun Xie
Chemical modification is an efficient strategy for improving wood quality; however, for some fast-grown wood species unwanted shrinkage occur upon treatment with alkaline solution. This study was devised to reveal the shrinkage behavior of poplar and radiata pine woods treated with 5, 10, 15 and 20 % alkaline sodium silicate (SS) solutions. Wood treated with sodium hydroxide (SH) solution adjusting to the same pH as the specific SS solution was used as a reference sample. The weight loss, chemical components analysis, and confocal microscopy revealed that treatments with SS caused considerable reductions in hemicellulose and acid-insoluble lignin (AIL) of poplar wood up to 51 % and 21 %, respectively. In contrast, such reductions of the SS-treated radiata pine wood were only 13 % and 2 %, respectively. Consequently, shrinkage of poplar wood in the tangential- and radial-directions reached up to 22 % and 11 % respectively. However, such shrinkage for radiata pine was less than 2 % in either direction. The crystallinity index of poplar and radiata pine woods after treatment increased up to 35.3 % and 4.8 %, respectively, attributable to removal of the amorphous fraction. The scanning electron microscopy displayed that treatments had minor effect on the cell structure of radiata pine, but brought about significant collapse of poplar cells. The above results show that radiata pine is more chemically stable to alkaline treatment than poplar.
{"title":"Shrinkage of poplar and radiata pine wood after treatment with sodium silicate and sodium hydroxide","authors":"Thi Tham Nguyen, Cong Chi Tran, Thi Vinh Khanh Nguyen, Trong Kien Nguyen, Zefang Xiao, Yanjun Xie","doi":"10.1515/hf-2023-0097","DOIUrl":"https://doi.org/10.1515/hf-2023-0097","url":null,"abstract":"Chemical modification is an efficient strategy for improving wood quality; however, for some fast-grown wood species unwanted shrinkage occur upon treatment with alkaline solution. This study was devised to reveal the shrinkage behavior of poplar and radiata pine woods treated with 5, 10, 15 and 20 % alkaline sodium silicate (SS) solutions. Wood treated with sodium hydroxide (SH) solution adjusting to the same pH as the specific SS solution was used as a reference sample. The weight loss, chemical components analysis, and confocal microscopy revealed that treatments with SS caused considerable reductions in hemicellulose and acid-insoluble lignin (AIL) of poplar wood up to 51 % and 21 %, respectively. In contrast, such reductions of the SS-treated radiata pine wood were only 13 % and 2 %, respectively. Consequently, shrinkage of poplar wood in the tangential- and radial-directions reached up to 22 % and 11 % respectively. However, such shrinkage for radiata pine was less than 2 % in either direction. The crystallinity index of poplar and radiata pine woods after treatment increased up to 35.3 % and 4.8 %, respectively, attributable to removal of the amorphous fraction. The scanning electron microscopy displayed that treatments had minor effect on the cell structure of radiata pine, but brought about significant collapse of poplar cells. The above results show that radiata pine is more chemically stable to alkaline treatment than poplar.","PeriodicalId":13083,"journal":{"name":"Holzforschung","volume":"27 1","pages":""},"PeriodicalIF":2.4,"publicationDate":"2024-03-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140057691","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The glass transition temperatures (Tg) of native, residual, and technical lignins are important to lignocellulose pulping, pulp processing and side stream utilization; however, how the structural changes from native to residual and technical lignin influences Tg has proven difficult to elucidate. Since the Tg of macromolecules is greatly influenced by the molecular weight, low-molecular-weight fractions, such as milled wood lignin (MWL), are poor representatives of lignin in the cell wall. To circumvent this problem, lignins of both high yield and purity were isolated from Norway spruce and softwood kraft pulp using the enzymatic mild acidolysis lignin (EMAL) protocol. Technical softwood kraft lignin was also fractionated into groups of different molecular weights, to acquire lignin that spanned over a wide molecular-weight range. A powder sample holder for dynamic mechanical analysis (DMA), was used to determine the Tg of lignins, for which calorimetric methods were not sensitive enough. The Tgs of EMAL were found to be closer to their in situ counterparts than MWL.
原生木质素、残留木质素和工业木质素的玻璃化转变温度（T g）对木质纤维素制浆、纸浆加工和副流利用非常重要；然而，从原生木质素到残留木质素和工业木质素的结构变化如何影响 T g 却很难阐明。由于大分子的 T g 受分子量影响很大，因此低分子量馏分（如碾磨木质素 (MWL)）不能很好地代表细胞壁中的木质素。为了避免这一问题，我们采用酶法温和酸解木质素（EMAL）方案从挪威云杉和软木牛皮浆中分离出了高产率和高纯度的木质素。技术软木牛皮浆木质素也被分成了不同分子量的组，以获得跨越宽分子量范围的木质素。使用动态机械分析（DMA）的粉末样品架来测定木质素的 T g，因为热量测定法对其不够灵敏。结果发现，EMAL 的 T gs 比 MWL 更接近其原位对应物。
{"title":"The glass transition temperature of isolated native, residual, and technical lignin","authors":"Åke Henrik-Klemens, Fabio Caputo, Roujin Ghaffari, Gunnar Westman, Ulrica Edlund, Lisbeth Olsson, Anette Larsson","doi":"10.1515/hf-2023-0111","DOIUrl":"https://doi.org/10.1515/hf-2023-0111","url":null,"abstract":"The glass transition temperatures (<jats:italic>T</jats:italic> <jats:sub>g</jats:sub>) of native, residual, and technical lignins are important to lignocellulose pulping, pulp processing and side stream utilization; however, how the structural changes from native to residual and technical lignin influences <jats:italic>T</jats:italic> <jats:sub>g</jats:sub> has proven difficult to elucidate. Since the <jats:italic>T</jats:italic> <jats:sub>g</jats:sub> of macromolecules is greatly influenced by the molecular weight, low-molecular-weight fractions, such as milled wood lignin (MWL), are poor representatives of lignin in the cell wall. To circumvent this problem, lignins of both high yield and purity were isolated from Norway spruce and softwood kraft pulp using the enzymatic mild acidolysis lignin (EMAL) protocol. Technical softwood kraft lignin was also fractionated into groups of different molecular weights, to acquire lignin that spanned over a wide molecular-weight range. A powder sample holder for dynamic mechanical analysis (DMA), was used to determine the <jats:italic>T</jats:italic> <jats:sub>g</jats:sub> of lignins, for which calorimetric methods were not sensitive enough. The <jats:italic>T</jats:italic> <jats:sub>g</jats:sub>s of EMAL were found to be closer to their <jats:italic>in situ</jats:italic> counterparts than MWL.","PeriodicalId":13083,"journal":{"name":"Holzforschung","volume":"11 1","pages":""},"PeriodicalIF":2.4,"publicationDate":"2024-03-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140034304","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Carbon fraction (CF) of trees is essential for quantifying forest carbon (C) stocks. Considerable attention has been paid to CF variations at various levels with the exception of inter- and intra-growth rings. Herein, the inter- and intra-growth ring variation of CF in Pinus tabuliformis was investigated. Elemental analysis was performed to obtain CF values of the earlywood and latewood in each growth ring of the xylem. Patterns of CF variation at the growth ring level were evaluated using mixed-effect models. The results showed that latewood CF, 50.6 %, was significantly higher than earlywood CF, 49.9 % (p < 0.01). In particular, inter-growth ring variations of CF differed between heartwood and sapwood, as well as between juvenile wood and mature wood. CF values decreased nonlinearly with cambium age toward the heartwood or juvenile wood, with estimated least-squares means of 50.4 % and 51.8 %, respectively. While CF values were almost unaltered in sapwood, and slightly decreased in mature wood, with estimated least-squares means of 50.0 % and 50.2 %, respectively. It indicates that patterns of CF variation between juvenile wood and mature wood are important to estimate the C stock of P. tabuliformis. This research provides insights into C uptake dynamics to support forest management and wood utilization.
{"title":"Inter- and intra-growth ring variations of wood carbon fractions in Pinus tabuliformis","authors":"Yupei Wei, Chang Zheng, Lingyu Ma, Xiaomei Jiang, Yafang Yin, Juan Guo","doi":"10.1515/hf-2023-0115","DOIUrl":"https://doi.org/10.1515/hf-2023-0115","url":null,"abstract":"Carbon fraction (CF) of trees is essential for quantifying forest carbon (C) stocks. Considerable attention has been paid to CF variations at various levels with the exception of inter- and intra-growth rings. Herein, the inter- and intra-growth ring variation of CF in <jats:italic>Pinus tabuliformis</jats:italic> was investigated. Elemental analysis was performed to obtain CF values of the earlywood and latewood in each growth ring of the xylem. Patterns of CF variation at the growth ring level were evaluated using mixed-effect models. The results showed that latewood CF, 50.6 %, was significantly higher than earlywood CF, 49.9 % (<jats:italic>p</jats:italic> < 0.01). In particular, inter-growth ring variations of CF differed between heartwood and sapwood, as well as between juvenile wood and mature wood. CF values decreased nonlinearly with cambium age toward the heartwood or juvenile wood, with estimated least-squares means of 50.4 % and 51.8 %, respectively. While CF values were almost unaltered in sapwood, and slightly decreased in mature wood, with estimated least-squares means of 50.0 % and 50.2 %, respectively. It indicates that patterns of CF variation between juvenile wood and mature wood are important to estimate the C stock of <jats:italic>P. tabuliformis</jats:italic>. This research provides insights into C uptake dynamics to support forest management and wood utilization.","PeriodicalId":13083,"journal":{"name":"Holzforschung","volume":"176 1","pages":""},"PeriodicalIF":2.4,"publicationDate":"2024-02-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139751942","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Daniel Konopka, Benjamin Grohmann, Jens Gecks, Wolfram Scheiding, Michael Kaliske
The hygroscopic and moisture-dependent mechanical characteristics of small-leaved lime wood (Tilia cordata) were investigated experimentally. This study includes sorption, swelling and shrinkage experiments, as well as tension and compression tests in the three principal anatomical directions at four relative humidity levels. Four sample groups from trees of three different locations in Germany were used. The findings are comparable to those of earlier studies. The hygro-expansion anisotropy is relatively small. Young’s moduli at tension/compression decreased by about 52 %/64 % in radial, 19 %/48 % in tangential and 16 %/58 % in longitudinal direction for an increase of moisture content from 10 % (65 % RH) to 20 % (95 % RH). Tension strengths/compression yield stresses decreased by about 25 %/45 % in radial, 9 %/42 % in tangential, and 32 % (compression) in longitudinal direction, respectively. These parameters increased with an increasing density. Based on the mechanical tests, Young’s modulus, tension strength and compression yield stress were derived as density- and moisture-dependent material model parameters. Shear modulus and shear strength were estimated by a theoretical approach. The experimental and modelling study was accompanied by a literature survey on characteristics of lime wood relevant for hygro-mechanical material modelling.
{"title":"Short-term hygro-mechanical behaviour of lime wood (Tilia cordata) in principal anatomical directions","authors":"Daniel Konopka, Benjamin Grohmann, Jens Gecks, Wolfram Scheiding, Michael Kaliske","doi":"10.1515/hf-2023-0029","DOIUrl":"https://doi.org/10.1515/hf-2023-0029","url":null,"abstract":"The hygroscopic and moisture-dependent mechanical characteristics of small-leaved lime wood (<jats:italic>Tilia cordata</jats:italic>) were investigated experimentally. This study includes sorption, swelling and shrinkage experiments, as well as tension and compression tests in the three principal anatomical directions at four relative humidity levels. Four sample groups from trees of three different locations in Germany were used. The findings are comparable to those of earlier studies. The hygro-expansion anisotropy is relatively small. Young’s moduli at tension/compression decreased by about 52 %/64 % in radial, 19 %/48 % in tangential and 16 %/58 % in longitudinal direction for an increase of moisture content from 10 % (65 % RH) to 20 % (95 % RH). Tension strengths/compression yield stresses decreased by about 25 %/45 % in radial, 9 %/42 % in tangential, and 32 % (compression) in longitudinal direction, respectively. These parameters increased with an increasing density. Based on the mechanical tests, Young’s modulus, tension strength and compression yield stress were derived as density- and moisture-dependent material model parameters. Shear modulus and shear strength were estimated by a theoretical approach. The experimental and modelling study was accompanied by a literature survey on characteristics of lime wood relevant for hygro-mechanical material modelling.","PeriodicalId":13083,"journal":{"name":"Holzforschung","volume":"11 1","pages":""},"PeriodicalIF":2.4,"publicationDate":"2024-02-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139752045","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Babar Hassan, Lesley Francis, R. Andrew Hayes, Maryam Shirmohammadi
Resin production in wood tissues is a regular feature of pine wood species, including southern pine. High resin contents of southern pine wood may increase wood resistance against decay fungi. The current study investigated the effect of resin contents in southern pine wood on decay resistance by exposing non-extracted heartwood, mixed wood (sapwood + heartwood), and sapwood blocks with varying resin content to brown rot, Fomitopsis ostreiformis in a laboratory decay test. Matching blocks of each wood type were successively extracted in a Soxhlet using three solvents to determine resin content and were exposed to decay fungus in parallel. Results showed that mass losses in non-extracted heartwood and mixed wood depended on resin content levels, and very shallow or no mass losses were observed in blocks containing more than 31 % resin content. Sapwood experienced high mass losses, but the presence of resinous extractives significantly increased the decay resistance. All solvent-extracted blocks experienced high mass loss (53–55 %). Scanning electron microscopy showed that penetration of brown rot hyphae and cell damage depended on the resin contents of blocks. Most of the identified compounds through GC-MS belonged to oleoresins, among which monoterpene hydrocarbons, oxygenated monoterpenoids, and sesquiterpenes were more abundant in heartwood than sapwood.
{"title":"Decay resistance of southern pine wood containing varying amounts of resin against Fomitopsis ostreiformis (Berk.) T. Hatt.","authors":"Babar Hassan, Lesley Francis, R. Andrew Hayes, Maryam Shirmohammadi","doi":"10.1515/hf-2023-0106","DOIUrl":"https://doi.org/10.1515/hf-2023-0106","url":null,"abstract":"Resin production in wood tissues is a regular feature of pine wood species, including southern pine. High resin contents of southern pine wood may increase wood resistance against decay fungi. The current study investigated the effect of resin contents in southern pine wood on decay resistance by exposing non-extracted heartwood, mixed wood (sapwood + heartwood), and sapwood blocks with varying resin content to brown rot, <jats:italic>Fomitopsis ostreiformis</jats:italic> in a laboratory decay test. Matching blocks of each wood type were successively extracted in a Soxhlet using three solvents to determine resin content and were exposed to decay fungus in parallel. Results showed that mass losses in non-extracted heartwood and mixed wood depended on resin content levels, and very shallow or no mass losses were observed in blocks containing more than 31 % resin content. Sapwood experienced high mass losses, but the presence of resinous extractives significantly increased the decay resistance. All solvent-extracted blocks experienced high mass loss (53–55 %). Scanning electron microscopy showed that penetration of brown rot hyphae and cell damage depended on the resin contents of blocks. Most of the identified compounds through GC-MS belonged to oleoresins, among which monoterpene hydrocarbons, oxygenated monoterpenoids, and sesquiterpenes were more abundant in heartwood than sapwood.","PeriodicalId":13083,"journal":{"name":"Holzforschung","volume":"73 1 1","pages":""},"PeriodicalIF":2.4,"publicationDate":"2024-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139668421","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The time domain nuclear magnetic resonance (TD-NMR) technique was employed to distinguish various water states, and the moisture migration during Elm wood (Ulmus rubra) heartwood vacuum drying was quantitatively analyzed. The transverse relaxation time (T2) was employed to establish the correlation between drying time and moisture migration. Additionally, the longitudinal relaxation time (T1) was utilized to identify two types of water states within the cell wall: OH bound water (B-water) and more freely bound water (C-water). Meanwhile, the changes in these two types of bound water during the drying were investigated. The results demonstrated an exponential decrease in the content of OH bound water and more freely bound water with drying time. OH bound water within the cell wall predominated, with only a small portion of more freely bound water experiencing migration loss when the moisture content (MC) dropped below 20 %. Furthermore, OH bound water exhibited higher migration rate compared to more freely bound water at 10–20 % MC, while the motion of OH bound water molecules became highly restricted and stronger binding to cell walls than more freely bound water at a MC level of below 10 %. These findings yield a theoretical foundation and empirical support for optimizing drying methods.
采用时域核磁共振（TD-NMR）技术来区分各种水状态，并对榆木（Ulmus rubra）心材真空干燥过程中的水分迁移进行了定量分析。采用横向弛豫时间（T2）来确定干燥时间与水分迁移之间的相关性。此外，还利用纵向松弛时间（T1）来确定细胞壁内的两种水状态：OH结合水（B-水）和更自由结合水（C-水）。同时，研究了这两种结合水在干燥过程中的变化。结果表明，随着干燥时间的延长，OH 结合水和更自由结合水的含量呈指数下降。当水分含量（MC）降至 20% 以下时，细胞壁内的羟基结合水占主导地位，只有一小部分自由结合水发生迁移损失。此外，在 MC 含量为 10%-20% 时，与自由结合水相比，OH 结合水的迁移率更高，而在 MC 含量低于 10% 时，OH 结合水分子的运动受到很大限制，与自由结合水相比，与细胞壁的结合力更强。这些发现为优化干燥方法提供了理论基础和经验支持。
{"title":"Elm wood (Ulmus rubra) vacuum drying at 40 °C studied by time domain nuclear magnetic resonance (TD-NMR)","authors":"Rui Tan, Zhihong Zhao, Wenjing Liu, Shuang Wu, Minghui Zhang","doi":"10.1515/hf-2023-0079","DOIUrl":"https://doi.org/10.1515/hf-2023-0079","url":null,"abstract":"The time domain nuclear magnetic resonance (TD-NMR) technique was employed to distinguish various water states, and the moisture migration during Elm wood (<jats:italic>Ulmus rubra</jats:italic>) heartwood vacuum drying was quantitatively analyzed. The transverse relaxation time (T2) was employed to establish the correlation between drying time and moisture migration. Additionally, the longitudinal relaxation time (T1) was utilized to identify two types of water states within the cell wall: OH bound water (B-water) and more freely bound water (C-water). Meanwhile, the changes in these two types of bound water during the drying were investigated. The results demonstrated an exponential decrease in the content of OH bound water and more freely bound water with drying time. OH bound water within the cell wall predominated, with only a small portion of more freely bound water experiencing migration loss when the moisture content (MC) dropped below 20 %. Furthermore, OH bound water exhibited higher migration rate compared to more freely bound water at 10–20 % MC, while the motion of OH bound water molecules became highly restricted and stronger binding to cell walls than more freely bound water at a MC level of below 10 %. These findings yield a theoretical foundation and empirical support for optimizing drying methods.","PeriodicalId":13083,"journal":{"name":"Holzforschung","volume":"23 1","pages":""},"PeriodicalIF":2.4,"publicationDate":"2024-01-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139501029","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Romain Viala, Jérémy Cabaret, Marjan Sedighi-Gilani, Vincent Placet, Scott Cogan
In this study, the influence of “bear claw” or indented growth ring anatomical patterns on the vibro-mechanical behavior of spruce wood have been investigated, particularly in the context of utilizing these singularities/specific features for the construction of violins. By employing vibrometry and modal analysis followed by finite element model updating, the vibro-mechanical properties (specific stiffness in longitudinal (L) and radial (R) directions and shear LR plane, and associated damping) of the indented growth rings spruce were identified and implemented in a numerical model of a violin. Results have revealed a significant increase in specific moduli in R direction and LR plane and decrease in L direction of spruce wood in the presence of indented growth rings, therefore accompanied by a reduction in anisotropic elastic properties, in comparison to spruce without these patterns. These properties led to changes in violin dynamics, globally increasing resonance frequencies and changing the shape of the vibration modes. The simulated frequency response function of the violin at the bridge suggested a global shift of the admittance of the bridge toward higher frequencies. These results suggest a potential impact of indented growth rings of spruce on the acoustic properties of instruments.
本研究调查了 "熊爪 "或凹陷生长环解剖形态对云杉木材振动力学行为的影响，特别是在利用这些奇异/特殊特征制造小提琴的背景下。通过采用测振法和模态分析以及有限元模型更新，确定了缩进生长环云杉的振动机械特性（纵向（L）和径向（R）方向和剪切LR平面的比刚度以及相关阻尼），并将其应用于小提琴的数值模型中。研究结果表明，与无凹陷生长环的云杉相比，有凹陷生长环的云杉木材在 R 向和 LR 面的比模量明显增加，而在 L 向的比模量则有所减少，因此各向异性弹性特性也随之降低。这些特性导致了小提琴动力学的变化，在整体上增加了共振频率，改变了振动模式的形状。琴桥处的小提琴模拟频率响应函数表明，琴桥的导纳总体上向高频移动。这些结果表明，云杉的缩进生长环可能会对乐器的声学特性产生影响。
{"title":"Effect of indented growth rings on spruce wood mechanical properties and subsequent violin dynamics","authors":"Romain Viala, Jérémy Cabaret, Marjan Sedighi-Gilani, Vincent Placet, Scott Cogan","doi":"10.1515/hf-2023-0090","DOIUrl":"https://doi.org/10.1515/hf-2023-0090","url":null,"abstract":"In this study, the influence of “bear claw” or indented growth ring anatomical patterns on the vibro-mechanical behavior of spruce wood have been investigated, particularly in the context of utilizing these singularities/specific features for the construction of violins. By employing vibrometry and modal analysis followed by finite element model updating, the vibro-mechanical properties (specific stiffness in longitudinal (L) and radial (R) directions and shear LR plane, and associated damping) of the indented growth rings spruce were identified and implemented in a numerical model of a violin. Results have revealed a significant increase in specific moduli in R direction and LR plane and decrease in L direction of spruce wood in the presence of indented growth rings, therefore accompanied by a reduction in anisotropic elastic properties, in comparison to spruce without these patterns. These properties led to changes in violin dynamics, globally increasing resonance frequencies and changing the shape of the vibration modes. The simulated frequency response function of the violin at the bridge suggested a global shift of the admittance of the bridge toward higher frequencies. These results suggest a potential impact of indented growth rings of spruce on the acoustic properties of instruments.","PeriodicalId":13083,"journal":{"name":"Holzforschung","volume":"148 1","pages":""},"PeriodicalIF":2.4,"publicationDate":"2024-01-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139500908","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This study aims to reveal the diversity of thermal-softening temperatures and identify the factors that determine this temperature. To achieve this, the thermal-softening properties of the radial direction of wood were measured under water-saturated conditions for 15 softwood and 72 hardwood specimens. Wood samples were obtained from the xylarium of the Forestry and Forest Products Research Institute, Japan. A dynamic viscoelastic measurement was performed on samples with uniform heating and cooling history because the difference in cooling rate can alter in the mechanical properties of wood. The storage and loss elastic moduli increased linearly as wood density increased, regardless of the wood species. However, the thermal-softening temperature (defined in this study as the peak temperature of loss tangent) was unrelated to the density, anatomical features, species, latitude, and annual rainfall in the habitat. When the relationship between thermal-softening temperature and lignin structure was investigated, a negative correlation was observed between the thermal-softening temperature and the syringyl ratio (syringyl/(syringyl+guaiacyl)) of lignin aromatics. This indicates that the thermal-softening temperature is higher for wood species with denser lignin structures, supporting the prior research showed correlation between thermal-softening temperature and methoxyl group content of wood.
{"title":"Influence of habitat, density, lignin structure, and extraction treatment on thermal-softening properties of water-swollen wood: a study of 87 wood specimens","authors":"Yuka Miyoshi, Hisashi Abe, Hiroaki Horiyama, Keisuke Kojiro, Yuzo Furuta","doi":"10.1515/hf-2023-0083","DOIUrl":"https://doi.org/10.1515/hf-2023-0083","url":null,"abstract":"This study aims to reveal the diversity of thermal-softening temperatures and identify the factors that determine this temperature. To achieve this, the thermal-softening properties of the radial direction of wood were measured under water-saturated conditions for 15 softwood and 72 hardwood specimens. Wood samples were obtained from the xylarium of the Forestry and Forest Products Research Institute, Japan. A dynamic viscoelastic measurement was performed on samples with uniform heating and cooling history because the difference in cooling rate can alter in the mechanical properties of wood. The storage and loss elastic moduli increased linearly as wood density increased, regardless of the wood species. However, the thermal-softening temperature (defined in this study as the peak temperature of loss tangent) was unrelated to the density, anatomical features, species, latitude, and annual rainfall in the habitat. When the relationship between thermal-softening temperature and lignin structure was investigated, a negative correlation was observed between the thermal-softening temperature and the syringyl ratio (syringyl/(syringyl+guaiacyl)) of lignin aromatics. This indicates that the thermal-softening temperature is higher for wood species with denser lignin structures, supporting the prior research showed correlation between thermal-softening temperature and methoxyl group content of wood.","PeriodicalId":13083,"journal":{"name":"Holzforschung","volume":"56 1","pages":""},"PeriodicalIF":2.4,"publicationDate":"2024-01-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139482051","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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