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Rheology and Mechanical Properties of Wood and Wood-Based Materials

A special issue of Materials (ISSN 1996-1944). This special issue belongs to the section "Advanced Composites".

Deadline for manuscript submissions: closed (10 August 2023) | Viewed by 27724

Special Issue Editors


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Guest Editor
Faculty of Forestry, Wood Sciences and Design, Laboratory of Wood Science and Technology, University of Thessaly, 43100 Karditsa, Greece
Interests: physical and mechanical properties of wood; wood-water relationships; chemical modification of wood; wood protection technologies; fire retardancy of wood and wood-based materials

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Guest Editor
1. Department of Wood Science and Thermal Techniques, Faculty of Forestry and Wood Technology, Poznan University of Life Sciences, Wojska Polskiego 38/42, 60-637 Poznan, Poland
2. BioComposites Centre, Bangor University, Deiniol Road, Bangor, Gwynedd LL57 2UW, UK
Interests: wood composition and structure; wood characterisation; wood modification; wood conservation; waterlogged archaeological wood; structure-function relations; wood decay; organosilicons in wood conservation
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Special Issue Information

Dear Colleagues,

Being natural, renewable and environmentally friendly, wood is a highly versatile material that has always been a common choice for many applications, including the production of tools, furniture, or art objects. Furthermore, its exceptional mechanical properties make wood also a preferable structural material for construction purposes. Some species of wood can be even stronger than steel or concrete. Although wood mechanical properties have been broadly investigated, further intensive research in this area is still in progress to provide more detailed knowledge of the relationships between wood structure, composition and mechanical properties that would allow us to improve further the performance of wood under different environmental conditions, as well as broaden its applications.

This Special Issue aims to present updated knowledge relating to the mechanical and viscoelastic performance of wood and wood-based materials under various conditions, to report on the progress in the enhancement of wood mechanical properties by means of different treatments, to review the relationships between wood structure, chemical composition, moisture content and its mechanical performance, and to demonstrate cutting-edge advances in the development of modern wood-based materials of enhanced mechanical properties.

The topics of interest include, but are not limited, to the following:

  • Relationships between wood chemical composition and its mechanical properties.
  • Effect of moisture on the mechanical and rheological properties of wood and wood-based materials.
  • Mechanical properties of weathered and decayed wood.
  • Effects of different treatments on the viscoelastic behaviour and mechanical properties of wood and wood-based materials.
  • Effects of wood structure and density on its mechanical properties and viscoelastic behaviour.
  • New methods and processes to upgrade the wood mechanical performance.
  • Mechanical properties of wood-based composite materials.
  • New methods for the assessment of wood viscoelastic behaviour and mechanical properties.
  • Novel wood-based materials with enhanced mechanical performance.
  • Mechanical properties of waterlogged wood and archaeological wood.

We highly encourage contributions from all relevant fields in the form of original or review articles.

With kind regards,

Prof. Dr. George Mantanis
Dr. Magdalena Broda
Guest Editors

Manuscript Submission Information

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Keywords

  • wood rheology
  • viscoelastic behaviour
  • modulus of elasticity
  • modulus of rupture
  • hardness
  • compression strength
  • tensile strength
  • shear strength
  • static bending
  • impact bending

Published Papers (14 papers)

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Research

20 pages, 1992 KiB  
Article
The Effects of Seawater Treatment on Selected Coniferous Wood Types
by Kamil Roman, Mateusz Leszczyński, Seweryn Pycka and Witold Jan Wardal
Materials 2023, 16(17), 5831; https://doi.org/10.3390/ma16175831 - 25 Aug 2023
Cited by 2 | Viewed by 894
Abstract
The mechanical strength of wood from Scots pine (Pinus sylvestris), European larch (Larix decidua), and Norway spruce (Picea abies) was studied using static compression tests. The material was exposed under constant soaking in water with salinity of [...] Read more.
The mechanical strength of wood from Scots pine (Pinus sylvestris), European larch (Larix decidua), and Norway spruce (Picea abies) was studied using static compression tests. The material was exposed under constant soaking in water with salinity of 7‰. The liquid mix was prepared according to a value roughly equivalent to the average salinity along the entire length of the Baltic Sea. The mechanical strength and quality of the raw material were determined using a sea salt saturation test, which determined the adhesion of the raw material to the extrusion process (permissible stress). An investigation was conducted to determine the physicochemical parameters of the material that was tested. It was investigated how much mineral compounds were absorbed over four cycles lasting a total of six weeks during the test. According to the statistical analysis, the chemical composition of wood and the presence of salts and mineral compounds correlated with its mechanical strength. An important part of the study focused on examining the factors affecting the construction of coniferous wood structures. The preparation of the raw material correctly can provide information on how the material can be protected during exposure to specific environmental conditions for longer. Full article
(This article belongs to the Special Issue Rheology and Mechanical Properties of Wood and Wood-Based Materials)
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17 pages, 6304 KiB  
Article
Creep Behavior of CLT Beams with Finite Thickness Layers of Flexible Adhesives
by Klaudia Śliwa-Wieczorek, Paweł Szeptyński, Tomasz Kozik and Martino Gubert
Materials 2023, 16(12), 4484; https://doi.org/10.3390/ma16124484 - 20 Jun 2023
Cited by 2 | Viewed by 1121
Abstract
Creep behavior of Cross-Laminated-Timber (CLT) beams with a finite-thickness layer of flexible adhesives is investigated. Creep tests were carried out for all component materials as well as for the composite structure itself. Three-point bending creep tests were performed for spruce planks and for [...] Read more.
Creep behavior of Cross-Laminated-Timber (CLT) beams with a finite-thickness layer of flexible adhesives is investigated. Creep tests were carried out for all component materials as well as for the composite structure itself. Three-point bending creep tests were performed for spruce planks and for CLT beams, and uniaxial compression creep tests were performed for two flexible polyurethane adhesives: Sika® PS and Sika® PMM. All materials are characterized with the use of the three-element Generalized Maxwell Model. The results of creep tests for component materials were used in elaboration of the Finite Element (FE) model. The problem of linear theory of viscoelasticity was solved numerically with the use of the Abaqus software. Obtained results of Finite Element Analysis (FEA) are compared with experimental results. Full article
(This article belongs to the Special Issue Rheology and Mechanical Properties of Wood and Wood-Based Materials)
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9 pages, 1563 KiB  
Article
Study on the Wood Characteristics of the Chinese Ancient Ship Luoyang I
by Xinyou Liu, Wanrong Ma, Xinwei Tu, Houyi Huang and Anca Maria Varodi
Materials 2023, 16(3), 1145; https://doi.org/10.3390/ma16031145 - 29 Jan 2023
Cited by 2 | Viewed by 1552
Abstract
Luoyang No.1 is a Qing Dynasty (1644–1902) inland river ancient wooden shipwreck discovered in September 2013. It adds significantly to the study of Grand Canal transport history and Luoyang’s economic history. The wood characteristics of Luoyang No.1 were investigated in this study using [...] Read more.
Luoyang No.1 is a Qing Dynasty (1644–1902) inland river ancient wooden shipwreck discovered in September 2013. It adds significantly to the study of Grand Canal transport history and Luoyang’s economic history. The wood characteristics of Luoyang No.1 were investigated in this study using chemical compositions, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), nano-indentation (NI), and scanning electron microscopy (SEM). The results showed that the holocellulose content was only 32.84–37.69%, indicating that the cellulose and hemicellulose had been seriously degraded. Based on the XRD pattern, the degree of crystallinity of cellulose in wood ranged from 19.82 to 22.83%. The nano-indentation demonstrated that compared with the undegraded contemporary wood, the elastic modulus and hardness of the ancient ship wood decreased by 45.5% and 32.1%, respectively. Furthermore, the FTIR spectra revealed that the biological deterioration of ancient wood was indicated by a decrease in the peaks related to cellulose and hemicellulose, but the change in lignin was insignificant. The results could provide knowledge for appropriate dewatering, strengthening, restoration strategies and regulation of the museum environment. Full article
(This article belongs to the Special Issue Rheology and Mechanical Properties of Wood and Wood-Based Materials)
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10 pages, 2017 KiB  
Article
Characteristics of Ancient Shipwreck Wood from Huaguang Jiao No. 1 after Desalination
by Xinyou Liu, Lulu Zhu, Xinwei Tu, Changjun Zhang, Houyi Huang and Anca Maria Varodi
Materials 2023, 16(2), 510; https://doi.org/10.3390/ma16020510 - 5 Jan 2023
Cited by 4 | Viewed by 1448
Abstract
Huaguangjiao I refers to the ancient Chinese wooden shipwreck of the South Song Dynasty (1127–1279 AD) discovered in the South China Sea in 1996. From 2008 to 2017, the archaeological waterlogged wood was desalted using deionized water combined with ultrasonic treatment, and desalted [...] Read more.
Huaguangjiao I refers to the ancient Chinese wooden shipwreck of the South Song Dynasty (1127–1279 AD) discovered in the South China Sea in 1996. From 2008 to 2017, the archaeological waterlogged wood was desalted using deionized water combined with ultrasonic treatment, and desalted using EDTA-2Na, EDTAHO, and NaH2PO4·2H2O solutions. In this paper, the degree of degradation of the modified waterlogged archaeological wood and the moisture and content of the main components were determined. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), nanoindentation (NI), and scanning electron microscopy (SEM) were employed to investigate the state of wood degradation after desalination and desulfurization. The results showed that the water content of the wood was as high as 532~1149%, while the basic density was only 0.14~0.18 g/cm3, indicating that the wood had been seriously degraded. The holocellulose content was only 36–40%. Based on the XRD patterns, the degree of cellulose crystallinity in the modified wood was 14.08%. The elastic modulus and hardness of the ancient shipwreck wood after desalination and desulfurization were 1.28–4.31 and 0.10–0.28 GPa, respectively, according to nanoindentation. In addition, the FTIR spectra revealed that the biological deterioration of the modified wood caused cellulose and hemicellulose degradation, but no apparent lignin alteration occurred. The results could provide knowledge for appropriate dewatering, strengthening, and restoration strategies. Full article
(This article belongs to the Special Issue Rheology and Mechanical Properties of Wood and Wood-Based Materials)
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11 pages, 2688 KiB  
Article
Characteristics of Ancient Ship Wood from Taicang of the Yuan Dynasty
by Xinyou Liu, Xin Xu, Xinwei Tu, Wanrong Ma, Houyi Huang and Anca Maria Varodi
Materials 2023, 16(1), 104; https://doi.org/10.3390/ma16010104 - 22 Dec 2022
Cited by 8 | Viewed by 1736
Abstract
In this study, wood samples extracted from the Taicang ancient ship, dating back to the Yuan Dynasty, were investigated to study the characteristics of waterlogged archaeological wood. The macroscopic characteristics and microscopic structures were used to identify the wood species. To assess the [...] Read more.
In this study, wood samples extracted from the Taicang ancient ship, dating back to the Yuan Dynasty, were investigated to study the characteristics of waterlogged archaeological wood. The macroscopic characteristics and microscopic structures were used to identify the wood species. To assess the degree of degradation of the waterlogged archaeological wood, X-ray diffraction (XRD), nanoindentation (NI), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM) were used to compare the new and ancient wood samples from the same species. The microscopic structures of the samples were identified as Pinus massoniana. The XRD and nanoindentation results revealed that the crystallinity index of the cellulose decreased from 41.07% to 33.85%, the elastic modulus was reduced by 20.90%, and hardness was reduced by 55.6% compared with the new wood. The FTIR spectra revealed that biological deterioration occurred in the cellulose and hemicellulose, but there was no noticeable change in the lignin content. These results provide helpful information for the conservation and restoration of ancient ships. Full article
(This article belongs to the Special Issue Rheology and Mechanical Properties of Wood and Wood-Based Materials)
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13 pages, 5524 KiB  
Article
Experimental Test of Reinforced Timber of FRCM-PBO with Pull-Off Adhesion Method
by Piotr Sokołowski, Paulina Bąk-Patyna, Dominika Bysiec and Tomasz Maleska
Materials 2022, 15(21), 7702; https://doi.org/10.3390/ma15217702 - 2 Nov 2022
Cited by 1 | Viewed by 1243
Abstract
The article describes the results of pull-off adhesion strength of the FRCM-PBO (Fiber Reinforced Cementitious Matrix-p-Phenylene benzobis oxazole) composite adhered to the epoxy resin layer which is the connector with the timber beam. In addition, this paper shows the results of the tests [...] Read more.
The article describes the results of pull-off adhesion strength of the FRCM-PBO (Fiber Reinforced Cementitious Matrix-p-Phenylene benzobis oxazole) composite adhered to the epoxy resin layer which is the connector with the timber beam. In addition, this paper shows the results of the tests of resistance to pull-off the epoxy resin layer from the pine beam. The tests were carried out based on the Polish Standard PN-EN 1542. The Pearson linear correlation analysis was also carried out in order to determine the correlation between the obtained results and the destructive forces. The factors that occurred during the test that may affect its results, such as the method of applying the bursting force, surface preparation of the tested elements and the types of substrate destruction, were also characterized. The experimental data show that in all the tested samples, non-initial adhesive destruction between the adhesive layer and the disc was observed. Full article
(This article belongs to the Special Issue Rheology and Mechanical Properties of Wood and Wood-Based Materials)
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15 pages, 3578 KiB  
Article
Low-Density Particleboards Modified with Blowing Agents—Characteristic and Properties
by Piotr Boruszewski, Piotr Borysiuk, Agnieszka Jankowska and Jolanta Pazik
Materials 2022, 15(13), 4528; https://doi.org/10.3390/ma15134528 - 27 Jun 2022
Cited by 6 | Viewed by 1703
Abstract
Although lightweight particleboards have been commercially available for years, they still have a number of disadvantages, including difficulty to process, brittleness, low impact strength, and other mechanical resistance. The aim of the paper was to determine the possibility of producing particleboards of reduced [...] Read more.
Although lightweight particleboards have been commercially available for years, they still have a number of disadvantages, including difficulty to process, brittleness, low impact strength, and other mechanical resistance. The aim of the paper was to determine the possibility of producing particleboards of reduced density (dedicated for furniture industry) as a result of using blowing agents from the group of hydrazides, dicarboxamides, or tetrazoles, which were modifiers of the adhesive resin used for bonding the particles of the core layer of three-layer particleboards. The concept presents the possibility of producing low-density particleboards in a standard technological process by modifying the adhesive resin, which has not been practiced by others until now. Analysis of the results of testing the particleboards properties with various types of modifiers (blowing agents), glue content (high 10%/12% and low 8%/10%), differing in glue dosing method, and different particle sizes allowed concluding that the most satisfactory effect was found in particleboards made of the variant modified with p-toluenesulfonyl hydrazide. This variant was characterised by the highest mechanical properties (bending strength, modulus elasticity, and internal bond strength) with high dimensional stability. The presented technology proposal can be applied in the industry. Full article
(This article belongs to the Special Issue Rheology and Mechanical Properties of Wood and Wood-Based Materials)
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16 pages, 3481 KiB  
Article
Low-Density Particleboards Modified with Expanded and Unexpanded Fillers—Characteristics and Properties
by Piotr Boruszewski, Piotr Borysiuk, Agnieszka Jankowska and Jolanta Pazik
Materials 2022, 15(13), 4430; https://doi.org/10.3390/ma15134430 - 23 Jun 2022
Cited by 4 | Viewed by 2119
Abstract
Reducing the density of wood-based materials is a desirable research direction in the development of the wood-based materials sector. Even though lightweight wooden particleboards have been commercially available for many years, they still have a number of disadvantages, especially their low strength parameters. [...] Read more.
Reducing the density of wood-based materials is a desirable research direction in the development of the wood-based materials sector. Even though lightweight wooden particleboards have been commercially available for many years, they still have a number of disadvantages, especially their low strength parameters. The aim of this paper was to determine the possibility of producing particleboards of reduced density for use in the furniture industry, as a result of using expanded polystyrene and two types of microspheres (expanded and unexpanded) to modify the core layer of three-layer particleboards. Analysis of the results of testing the particleboards’ properties when using various types of modifiers (expanded and unexpanded fillers), urea formaldehyde (UF) glue content (high: 10%/12% and low: 8%/10%), various glue-dosing methods, and different particle sizes, allows us to conclude that the most satisfactory effect was found when using EPS. One partly positive effect was observed when using the Expancel-type 031 DU 40 as a filler; therefore, it is recommended that research be continued in this area. Using microspheres that have not been used before as a filler in the production of wood-based panels is the novelty of the presented research. The proposed technology has potential for application in the industry. Full article
(This article belongs to the Special Issue Rheology and Mechanical Properties of Wood and Wood-Based Materials)
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14 pages, 2502 KiB  
Article
Effect of the Longitudinal Tensile Creep on the Stiffness of Radiata Pine (Pinus radiata D. Don)
by Oswaldo Erazo, Judith Vergara-Figueroa, Paulina Valenzuela and William Gacitúa
Materials 2022, 15(12), 4314; https://doi.org/10.3390/ma15124314 - 18 Jun 2022
Cited by 1 | Viewed by 1816
Abstract
The influence of load on the cellulose microfibrils of single cells or thin wood foils is known. It can decrease the cellulose microfibril angles and, in turn, increase the stiffness. However, this modification of a piece of wood, which is made up of [...] Read more.
The influence of load on the cellulose microfibrils of single cells or thin wood foils is known. It can decrease the cellulose microfibril angles and, in turn, increase the stiffness. However, this modification of a piece of wood, which is made up of multiple cells, is unknown. The aim of this research was to study the effect of tensile creep on the longitudinal stiffness of radiata pine wood. The modulus of elasticity of each specimen was determined before and after being subjected to tensile creep. The samples were loaded at 1170 N and 1530 N for 20 min at 70 °C. The load was determined as a function of a percentage of the force at the proportional limit. The moduli of elasticity before and post-tensile creep showed no effect on the stiffness of wood at the macroscopic level, but neither were there damage to the cell structure. It can be assumed that there are changes at the microscopic level, but they are not enough to be reflected at the macro scale. It is also challenging to achieve the modifications that occur at the level of a single cell or in thin wood foils; however, the implications of this would be favorable for the development of stronger wood-based products. Full article
(This article belongs to the Special Issue Rheology and Mechanical Properties of Wood and Wood-Based Materials)
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14 pages, 3526 KiB  
Article
Influence of Pressing Schedule and Adhesive Content on the Rheological Behavior of Wood Fiber-Furnish Mats
by Ali Shalbafan and Heiko Thoemen
Materials 2022, 15(4), 1413; https://doi.org/10.3390/ma15041413 - 14 Feb 2022
Cited by 3 | Viewed by 1411
Abstract
In this study, for a better understanding of the hot-pressing process, the influence of adhesive content (AC) on various features of a typical pressing schedule for medium-density fiberboard (MDF) production, including fiber mat compressibility, heat transfer during hot-pressing, density profile and board properties, [...] Read more.
In this study, for a better understanding of the hot-pressing process, the influence of adhesive content (AC) on various features of a typical pressing schedule for medium-density fiberboard (MDF) production, including fiber mat compressibility, heat transfer during hot-pressing, density profile and board properties, were evaluated. It was found that increasing the AC (urea formaldehyde) leads to faster heat transfer towards the mat’s central plane, mainly due to higher heat release from the adhesive polycondensation reaction. Moreover, the results indicate that the time needed to reach the critical mark of 100 °C in the central plane of the mat depends on the duration of the first densification level (FD). Importantly, the pressure peaks (pmax and p2nd) needed for mat densification are significantly reduced when increasing the AC, which might be attributed to the slippery effect created by the adhesive on the fiber surfaces. The duration of the FD also showed obvious effects on the intermediate density maxima (ρinter) and the core layer density (ρcore). In general, the physical and mechanical properties of MDF panels are significantly impacted by the pressing schedule and AC. All in all, the results of this study are valuable information for refining existing rheological models to improve their accuracy and their ability to simulate the vertical density profile during industrial production. Full article
(This article belongs to the Special Issue Rheology and Mechanical Properties of Wood and Wood-Based Materials)
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15 pages, 3765 KiB  
Article
Statistical Modelling of the Fatigue Bending Strength of Norway Spruce Wood
by Jernej Klemenc and Gorazd Fajdiga
Materials 2022, 15(2), 536; https://doi.org/10.3390/ma15020536 - 11 Jan 2022
Cited by 1 | Viewed by 1646
Abstract
When wood is used as a structural material, the fact that it is a highly inhomogeneous material, which significantly affects its static and fatigue properties, presents a major challenge to engineers. In this paper, a novel approach to modelling the fatigue-life properties of [...] Read more.
When wood is used as a structural material, the fact that it is a highly inhomogeneous material, which significantly affects its static and fatigue properties, presents a major challenge to engineers. In this paper, a novel approach to modelling the fatigue-life properties of wood is presented. In the model, the common inverse-power-law relationship between the structural amplitude loads and the corresponding number of load cycles to failure is augmented with the influence of the wood’s mass density, the loading direction and the processing lot. The model is based on the two-parametric conditional Weibull’s probability density function with a constant shape parameter and a scale parameter that is a function of the previously mentioned parameters. The proposed approach was validated using the example of experimental static and fatigue-strength data from spruce beams. It turned out that the newly presented model is capable of adequately replicating the spruce’s S-N curves with a scatter, despite the relatively scarce amount of experimental data, which came from different production lots that were loaded in different directions and had a significant variation in density. Based on the experimental data, the statistical model predicts that the lower density wood has better fatigue strength. Full article
(This article belongs to the Special Issue Rheology and Mechanical Properties of Wood and Wood-Based Materials)
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14 pages, 7695 KiB  
Article
Factors That Affect the Mechanical Strength of Archaeological Wood—A Case Study of 18th-Century Wooden Water Pipes from Bóżnicza Street in Poznań, Poland
by Magdalena Broda, Carmen-Mihaela Popescu, Daniel Ilie Timpu, Dawid Rowiński and Edward Roszyk
Materials 2021, 14(24), 7632; https://doi.org/10.3390/ma14247632 - 11 Dec 2021
Cited by 2 | Viewed by 2830
Abstract
Large amounts of archaeological wood are often excavated during groundworks in cities and towns. Part of the unearthed artefacts is usually saved, conserved and then presented in museums. However, if the finding contains several similar objects, some of them could potentially be further [...] Read more.
Large amounts of archaeological wood are often excavated during groundworks in cities and towns. Part of the unearthed artefacts is usually saved, conserved and then presented in museums. However, if the finding contains several similar objects, some of them could potentially be further employed for some other practical purposes. The research aimed to determine the mechanical performance of the remains of wooden water mains excavated at Bóżnicza street in Poznań, Poland and evaluate its potential usefulness for any practical purposes. First, wood density was determined along with its mechanical strength in compression. The density of archaeological wood identified as Scots pine was lower than contemporary pinewood (383 kg × m−3 vs. 572 kg × m−3); therefore, its mechanical properties in compression tests were also lower, as expected, making the wood unsuitable for any practical applications. However, the differences in modulus of elasticity and compressive strength were not justified by the differences in wood density. Further infrared spectroscopy and X-ray diffraction analyses revealed additional differences in chemical composition and cellulose crystallinity between archaeological and contemporary wood. The results indicated the decrease in carbohydrate content and cellulose crystallinity in degraded wood, which, in addition to wood density, apparently contribute to the deterioration in mechanical strength of archaeological wood. The case study of the excavated archaeological wooden pipes shows that they have historical value but are not useful for practical purposes. It also revealed that not only wood density but also its chemical composition and cellulose crystallinity level has a substantial impact on the wood mechanical properties, particularly in compression. Full article
(This article belongs to the Special Issue Rheology and Mechanical Properties of Wood and Wood-Based Materials)
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11 pages, 3361 KiB  
Article
Hydrogen-Bonding-Aided Fabrication of Wood Derived Cellulose Scaffold/Aramid Nanofiber into High-Performance Bulk Material
by Xiaoshuai Han, Weijie Wu, Jingwen Wang, Zhiwei Tian and Shaohua Jiang
Materials 2021, 14(18), 5444; https://doi.org/10.3390/ma14185444 - 20 Sep 2021
Cited by 16 | Viewed by 3079
Abstract
Preparing a lightweight yet high-strength bio-based structural material with sustainability and recyclability is highly desirable in advanced applications for architecture, new energy vehicles and spacecraft. In this study, we combined cellulose scaffold and aramid nanofiber (ANF) into a high-performance bulk material. Densification of [...] Read more.
Preparing a lightweight yet high-strength bio-based structural material with sustainability and recyclability is highly desirable in advanced applications for architecture, new energy vehicles and spacecraft. In this study, we combined cellulose scaffold and aramid nanofiber (ANF) into a high-performance bulk material. Densification of cellulose microfibers containing ANF and hydrogen bonding between cellulose microfibers and ANF played a crucial role in enhanced physical and mechanical properties of the hybrid material. The prepared material showed excellent tensile strength (341.7 MPa vs. 57.0 MPa for natural wood), toughness (4.4 MJ/m3 vs. 0.4 MJ/m3 for natural wood) and Young’s modulus (24.7 GPa vs. 7.2 GPa for natural wood). Furthermore, due to low density, this material exhibited a superior specific strength of 285 MPa·cm3·g−1, which is remarkably higher than some traditional building materials, such as concrete, alloys. In addition, the cellulose scaffold was infiltrated with ANFs, which also improved the thermal stability of the hybrid material. The facile and top-down process is effective and scalable, and also allows one to fully utilize cellulose scaffolds to fabricate all kinds of advanced bio-based materials. Full article
(This article belongs to the Special Issue Rheology and Mechanical Properties of Wood and Wood-Based Materials)
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21 pages, 8109 KiB  
Article
The Viscoelastic Behaviour of Waterlogged Archaeological Wood Treated with Methyltrimethoxysilane
by Magdalena Broda, Morwenna J. Spear, Simon F. Curling and Graham A. Ormondroyd
Materials 2021, 14(18), 5150; https://doi.org/10.3390/ma14185150 - 8 Sep 2021
Cited by 10 | Viewed by 2635
Abstract
Waterlogged wood treatment with methyltrimethoxysilane (MTMS) proved effective in stabilising wood dimensions upon drying (anti-shrink efficiency of 76–93%). Before the method can be proposed as a reliable conservation treatment, further research is required that includes the evaluation of the mechanical properties of treated [...] Read more.
Waterlogged wood treatment with methyltrimethoxysilane (MTMS) proved effective in stabilising wood dimensions upon drying (anti-shrink efficiency of 76–93%). Before the method can be proposed as a reliable conservation treatment, further research is required that includes the evaluation of the mechanical properties of treated wood. The aim of the study was to characterise the effect of the treatment on the viscoelastic behaviour of archaeological waterlogged elm and oak wood differing in the degree of degradation. Dynamic mechanical analysis in the temperature range from −150 to +150 °C was used for the study. To better understand the viscoelastic behaviour of the treated wood, pore structure and moisture properties were also investigated using Scanning Electron Microscopy, nitrogen sorption, and Dynamic Vapour Sorption. The results clearly show that methyltrimethoxysilane not only prevents collapse and distortions of the degraded cell walls and decreases wood hygroscopicity (by more than half for highly degraded wood), but also reinforces the mechanical strength by increasing stiffness and resistance to deformation for heavily degraded wood (with an increase in storage modulus). However, the MTMS also has a plasticising effect on treated wood, as observed in the increased value of loss modulus and introduction of a new tan δ peak). On the one hand, methyltrimethoxysilane reduces wood hygroscopicity that reflects in lower wood moisture content, thus limiting the plasticising effect of water on wood polymers, but on the other hand, as a polymer itself, it contributes to the viscous behaviour of the treated wood. Interestingly, the effect of silane differs with both the wood species and the degree of wood degradation. Full article
(This article belongs to the Special Issue Rheology and Mechanical Properties of Wood and Wood-Based Materials)
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