Biological Durability Research Articles

Review of Heat Effect for wood Properties

This study aimed to analyse the effect of physical and mechanical properties of thermally wood. The study compiled information from review of literature that related to the thermo wood. One-way and two factors ANOVA table were used to analyses data. The result showed that thermo wood property was affected based on physical and mechanical. Physical property effective was density decreasing but improved biological durability. Mechanical property like hardness was increasing, but tension, MOR, compression was decreasing and MOE was not change.

Suitability of thermally modified wood for binderless particleboard production: Effects of temperature and moisture content in hot pressing

The use of thermally modified wood has grown significantly worldwide over the past 20 years owing to its natural, chemical-free properties, enhanced dimensional stability, and improved biological durability. The binderless particleboard (BP) production process offers an effective way to recycle waste from thermally modified wood. In this study, Fourier-transform infrared (FTIR) spectroscopy and modulated temperature technology were employed to investigate the chemical changes in thermally modified wood as a function of temperature. The impact of moisture content (MC) and temperature on the compression characteristics of particleboards was also examined. The resulting particleboards were subjected to tests for thickness swell and structural morphology (SEM) and vertical density profile analyses. The particleboards produced from thermally modified wood with an MC of 20 % and at a hot-pressing temperature of 170 °C exhibited superior properties to those produced at 8 % MC and 150 and 190 °C. This superior performance can be attributed to the chemical changes in wood, particle size, and the heat transfer and conductivity of the particleboards at high temperature and MC, which renders them more malleable during hot pressing. The particleboards manufactured at 20 % MC and at a hot-pressing temperature of 170 °C demonstrated an internal bonding (IB) of 0.77 MPa, a thickness swell (TS) of 8.14 %, and a homogeneous density distribution. The study provides valuable insights into the production of particleboards from thermally modified wood by optimising the MC and temperature conditions for hot pressing. This research offers a sustainable approach to reusing thermally modified wood waste and promotes the development of more efficient particleboard production processes. Future research could focus on broadening the application scope and exploring the long-term durability and performance of the particleboards produced under the identified optimal conditions.

Patient-derived mini-colons enable long-term modeling of tumor-microenvironment complexity.

Existing organoid models fall short of fully capturing the complexity of cancer because they lack sufficient multicellular diversity, tissue-level organization, biological durability and experimental flexibility. Thus, many multifactorial cancer processes, especially those involving the tumor microenvironment, are difficult to study ex vivo. To overcome these limitations, we herein implemented tissue-engineering and microfabrication technologies to develop topobiologically complex, patient-specific cancer avatars. Focusing on colorectal cancer, we generated miniature tissues consisting of long-lived gut-shaped human colon epithelia ('mini-colons') that stably integrate cancer cells and their native tumor microenvironment in a format optimized for real-time, high-resolution evaluation of cellular dynamics. We demonstrate the potential of this system through several applications: a comprehensive evaluation of drug effectivity, toxicity and resistance in anticancer therapies; the discovery of a mechanism triggered by cancer-associated fibroblasts that drives cancer invasion; and the identification of immunomodulatory interactions among different components of the tumor microenvironment. Similar approaches should be feasible for diverse tumor types.

Origin-specific differences in the durability of black locust (Robinia pseudoacacia) wood against wood-destroying basidiomycetes

Global climate change is accompanied by a change in tree composition in many regions. In Europe, the distribution areas of many species are expanding towards the north so that, among others, black locust (Robinia pseudoacacia), which is native to the USA and has long been established in south-eastern Europe, is also becoming increasingly important in central and northern Europe. Many other tree species are known to have different properties between their original and new locations, including the biological durability of the wood. Hence, the resistance of black locust wood against decay fungi was studied concerning origin-specific differences. Wood was sampled from seven different origins in Europe and original habitats in the United States. Fungal incubation experiments were conducted, wood extractives were analysed, and different anatomical characteristics were quantified such as ring width, vessel size distribution and the presence of tyloses. In addition to differences in durability between juvenile and mature wood, origin-specific differences within the mature heartwood were attributed to extractive contents and the percentages of earlywood vessels containing tyloses. Based on parameters that contributed at least 20% to mass loss, susceptibility to fungal decay was modelled with multiple regressions.

Oil Heat Treatment of Wood-A Comprehensive Analysis of Physical, Chemical, and Mechanical Modifications.

Wood, a natural material with versatile industrial applications, faces limitations such as low dimensional stability and decay resistance. To address these issues, there has been significant progress in wood modification research. Oil heat treatment has emerged as an effective method among environmentally friendly wood treatment options. Studies have indicated that treating wood with hot vegetable oils yields superior properties compared to traditional methods involving gaseous atmospheres, which is attributed to the synergistic effect of oils and heat. This comprehensive review investigates the physical, chemical, and mechanical modifications induced by the oil heat treatment of wood, along with its impact on biological durability against biotic agents. The review synthesizes recent research findings, elucidates underlying mechanisms, and discusses the implications for wood material science and engineering.

Enhancing water resistance and flame retardancy of wood through phytic acid catalyzed in-situ polyesterification

The treatment of wood using in-situ polyesterification with citric acid and D-sorbitol (SCA) is a novel method for enhancing wood properties. This method can effectively improve the dimensional stability and biological durability of wood. However, achieving effective fixation of polyester in wood at lower curing temperatures has not been achieved. In this study, phytic acid was used to catalyze in-situ polyesterification of SCA. The autocatalytic reaction pattern of SCA polyesterification was elucidated through an investigation of the kinetics of the curing reaction. It was also confirmed that phytic acid reduces the curing temperature and activation energy of SCA. The investigation of polyesters revealed that phytic acid catalysis enhances the esterification degree and thermal stability of the polyester. Wood treated with SCA and 2%wt phytic acid exhibited a 44% reduction in polyester leaching. Moreover, it demonstrated high water resistance and dimensional stability, with water repellency efficiency of up to 33.8% and anti-swelling efficiency of up to 46.2%. Remarkably, it exhibited excellent flame retardancy, with an oxygen index of 33.1% and a 47.5% reduction in total heat release. The outstanding flame retardancy is attributed to the dual action of phytic acid in both the solid phase and gas phase.

Comparative durability tests of preservative-treated and chemically modified wood – Assessment and classification on the basis of different decay tests

Not before the year 2016, the European standard system did allow for classifying the durability of treated wood in addition to natural durability of untreated wood species. After its latest revision, EN 350 (2016) allows a durability classification of solid wood and wood-based materials with the help of five durability classes (DC) between ‘very durable’ (DC 1) and ‘non-durable’ (DC 5). However, different test methods, assessment measures, and calculation methods can be used for durability classification. This inevitably leads to different assessments of the biological durability of wood. This study aimed therefore on a comparative durability classification of preservative-treated and chemically modified wood (here: treated with 1,3-dimethylol-4,5-dihydroxyethyleneurea, DMDHEU) using different laboratory and field test methods. Durability classes of the tested timbers differed not only between tested materials, but depended also on the applied test, assessment, and calculation method. In this respect, the use of relative values (x-values), i.e., mass loss (ML) or MOE loss data compared with a non-durable reference material can help to harmonize the classification and make DCs more comparable. The use of relative values can also help to reduce the effect of varying virulence of test fungi, activity of test soil substrates, and the climate-induced hazard of test sites.

A review on natural fiber composites: Polymer matrices, fiber surface treatments, fabrication methods, properties, and applications

AbstractHigh performance and durability are essential for goods to satisfy the needs of the expanding worldwide market. Wood plastic composites (WPCs) are materials made from a combination of wood, polymers, and additives. WPCs can be extruded, injected, compressed, or thermoformed. Presently, WPCs are manufactured using sophisticated processes including as laser sintering, fused layer modeling, and additive manufacturing. Properly managing the melt temperature and pressure is crucial in the manufacturing process of WPCs to ensure effective polymer incorporation. Natural fibers have distinct benefits for polymer composites, but they also have some serious drawbacks, like lower strength properties—especially lower impact strength than synthetic fibers—poor compatibility with hydrophobic polymers, poorer dimensional stability and moisture absorption due to hydroxly groups, a maximum processing temperature that is limited, thermal degradation above 200–220°C, and lower biological durability. The modification of the surface of the fibers improves the mentioned disadvantages of the natural fibers. High‐quality WPCs require the application of chemical or physical treatment to the wood fibers. This extensive review focused on the modification techniques applied to the surface of wood, manufacturing processes, and properties and applications of WPCs.Highlights Modification methods used in surface treatment of natural fibers was explained. Properties and recent applications of wood polymer composites were given. Optimum requirements of natural fibers and polymer matrices are given. Fabrication methods of natural fiber composites are extensively given.

Water-Related Properties and Biological Durability of Wood-Based Composites

There is insufficient data regarding the biodegradation of wood-based composites (WBC) by wood decay fungi. This study aimed to evaluate the biological durability and water-related properties of different WBC types. Although WBC are primarily designed for dry environments, in building applications, they may face increased moisture risks due to water leakage, condensation, or humid air. The panels, including oak-pine shield parquet (OPP), oriented strand board (OSB), birch plywood (BP), particle board (PB), laminated particle board (LPB), moisture-resistant particle board (MRPB), medium density fibreboard (MDF), laminated medium density fibreboard (LMDF) and moisture resistant medium density fibreboard (MRMDF), were subjected to attack by brown rot fungus Coniphora puteana. After 16 weeks of exposure, the most resistant WBC against biodegradation were BP, moisture-resistant MDF, and laminated MDF, as they exhibited a mass loss lower than 5 %. Conversely, all other WBC types showed high susceptibility to biodegradation, with a mass loss exceeding 35 %. LMDF (8 – 51 %) and MRMDF had the lowest water absorption (WA) within 168 h (2 – 46 %), while non-treated MDF exhibited the highest WA among all composite types with 190 % water uptake. With regards to thickness swelling, all WBC types, except for LPB and MDF, demonstrated values below 20 %. The influence of adhesives (phenol-formaldehyde or melamine urea-formaldehyde) used in WBC did not show a clear impact on water-related properties orbiological durability.

Biological durability and moisture dynamics of untreated and thermally modified poplar

Biological durability and moisture dynamics of untreated and thermally modified poplar

Biological durability and wood–water interactions of sorbitol and citric acid (SorCA) modified wood

This study aimed to investigate the relationship between moisture dynamics of sorbitol and citric acid (SorCA) modified wood and its biological durability. Specifically, the research aimed to determine the chemical loading needed for effective protection against wood-destroying basidiomycetes, while also improving the understanding of the moisture behavior of SorCA-modified wood. The SorCA modification process is relatively new, and thus, there is limited knowledge on its moisture behavior and its impact on biological durability. The research focused on Scots pine sapwood (Pinus sylvestris L.) and used the EN 113-2 standard to investigate its durability against wood-destroying basidiomycetes. Moisture behavior was analyzed through short-term water uptake and release tests, capillary water uptake and CEN/TS 16818. Results showed a significant reduction in liquid and water vapor uptake, likely due to a reduction in the maximum moisture capacity within the wood cell wall. The study confirmed that high chemical loadings (i.e., weight percent gain, WPG) are necessary for adequate decay protection.

Wood Modification Using Imidazole and Succinimide: Effects on Dimensional Stability and Bending Properties

The modification of Scots pine sapwood (Pinus sylvestris L.) with the heterocyclic compounds imidazole and succinimide was investigated. Pressure-impregnation with aqueous solutions containing imidazole, imidazole + citric acid, succinimide, succinimide + citric acid, and citric acid + sorbitol (CIOL®) with solid contents of 5%, 10%, and 15% was followed by oven-curing at 220 °C for 1 h. During the treatment steps, the changes in mass, bending properties, and anti-swelling efficiency (ASE) were examined. The results indicate that solid concentrations within the range of 5% to 10% were optimal. The results seem to show that there are two differing mechanisms in the modification of imidazole and succinimide, respectively. Mass loss due to heat treatment was highest in the imidazole-treated specimens, whereas it remained low and concentration-independent in the succinimide-treated specimens. After three cycles, the ASE reached 31% for the imidazole-treated specimens and improved to 38% with the addition of citric acid. For succinimide, the ASE increased from 17% to 41%. The bending properties generally showed improvement, except for succinimide + citric acid and CIOL®, which displayed a reduced modulus of rupture. Chemical analyses are warranted to fully understand the reaction mechanisms of these treatments. The positive effects of imidazole treatment are suggested to stem from a thermal reaction between the chemical and the wood, indicated by substantial mass loss during leaching and specimen darkening. Succinimide and citric acid might exhibit polymerization with each other and with wood components, which is akin to the CIOL® process. Further research should delve into the reaction mechanisms and the impact of imidazole and succinimide on biological durability.

Artificial weathering resistance and biological durability of surface-charred beech wood combined with linseed oil coating

Specimens of European beech wood (Fagus sylvatica L.) charred at 250 °C (4 min), 300 °C (2 min), and 350 °C (1 min) in combination with linseed oil coating were studied. The influence of the surface charring process and artificial weathering on surface discoloration, water absorption, and decay resistance were analyzed. Discoloration analysis showed a decrease in all parameters L*, a*, and b* due to the charring process. Coating with linseed oil caused a decrease in the L* parameter. An influence on parameters a* and b* was also demonstrated. As a result of the artificial weathering, the L* parameter increased in almost all groups. The group charred at 350 °C showed a decrease in L*. The parameters a* and b* were also affected. The effect of oil coating on discoloration during artificial weathering was negligible. The average water absorption of uncoated charred specimens decreased more than 50%. Damage due to artificial weathering disrupted the effect of the charring process. The effect of oil coating decreased depending on the length of partial immersion. Surface charring and oil impregnation slightly reduced the loss of beech wood mass caused by T. versicolor and P. placenta but could not fully protect the wood.

The effects of surface modification by using phytic acid-based hybrid complexes on the interfacial properties of heat-treated wood

Heat-treated wood is widely used in outdoors due to its good dimensional stability and biological durability, while the reduced surface hydrophilicity negatively affects its bonding performance with water-soluble adhesives. In this work, a convenient surface modification strategy was prepared on heat-treated wood by surface modification with phytic acid or phytic acid combined with Fe3+ to improve its interfacial bonding properties. Results showed that the phytic acid and phytic acid-Fe3+ chelate are distributed both in the cell cavity and cell wall, and phytic acid surface coating is smooth while phytic acid-Fe3+ seemed layer-by-layer. These coatings bring a large number of hydroxyl groups to improve the surface wettability of heat-treated wood. Therefore, the water contact angle of both phytic acid treated wood and phytic acid-Fe3+ treated wood at 60 s is smaller than that on control wood. The water contact angle in the earlywood of phytic acid treated wood even reaches 0°. The average penetration and effective penetration of phenol formaldehyde adhesive into heat-treated wood also increase after treatment. On average, the average penetration and effective penetration value of phytic acid treated wood increased from 870 to 997 μm, and 35 to 62 μm, respectively. The average penetration value of phytic acid-Fe3+ treated wood is decreased due to the accumulation of chelates. But its effective penetration value is more than twice that of heat-treated wood. The digital image correlation results that the tensile strength of phytic acid treated wood is much higher than that of heat-treated wood. The shear strain of phytic acid treated wood is distributed more homogeneously. However, the maximum tensile stress of phytic acid-Fe3+ treated wood is poor due to the glueline being too thick to closely connect with wood.

Effect of compression ratios on the sorption behaviors of bamboo fiber-based composites

The sorption behaviors of bamboo fiber-based composites (BFC) play a critical role on its applications due to its impact on the dimensional stability and biological durability of the material. The sorption behaviors of Neosinocalamus affinis BFC with compression ratios of 1.50, 1.83 and 2.17 were studied in this project, aiming to optimize the manufacturing process of BFC to reduce the sorption of final products. It was found that the hygroscopicity of BFC samples with all three compression ratios is much lower than that of raw bamboo at all the studied relative humidity (RH) levels. The BFC manufactured with 1.50 compression ratios showed the lowest equilibrium moisture content (EMC). The sorption ability of BFC showed some increase with increasing compression ratio especially when the relative humidity (RH) was above 60%. An evolution in moisture absorption model of BFC was proposed based on the changes in its wettability, pore structures, and chemical compositions. Both introduction of phenolic formaldehyde (PF) resin and material densification reduced the water transfer pathway such as bamboo cell lumens, pits, and gaps, as well as the water absorption space in cell wall. Meanwhile, the BFC with higher compression ratio had increased difficulty to absorb water. The increase in sorption ability of BFC with higher compression ratio at high RH environment is proved to be the consequence of the higher content of its mesopore ratio resulting in increased poly-layer water content. Therefore, the RH of application occasions is critical to determine the optical compression ratio of BFC combining with other performance requirements.

Statistical Analysis of Wood Durability Data and Its Effect on a Standardised Classification Scheme

The biological durability of wood is an important property for outdoor applications of wood-based products. In temperate climate zones, the most critical biological hazard is wood-destroying fungi, and the European standard EN 350 in combination with EN 113-2 provide guidance on sampling, testing, and classifying wood durability against brown and white rot fungi. However, in their latest revised versions, both standards recommend the use of probability density functions for fitting mass loss data (ML). Subsequently, the durability of wood and its variability should be further characterised. The aim of this study was to statistically analyse the ML data from laboratory agar plate tests with different European-grown wood species and to examine the effect of different statistical treatments on the standardised classification scheme of wood durability. It was concluded that more precise guidance is needed on the sampling procedure since significant differences in durability exist between stem zones. The assignment of dispersion indicators requires a revision to ensure clear, unmistakable, and reproducible durability classification of wood. Deficits in the description of the proposed statistical treatments in both standards became evident. It can be questioned whether the application of probability density functions provides additional information about the variability of wood durability.

Laboratory Durability Testing of Preservative-Treated Wood Products

Recently, certain European standards have allowed for the classification of the biological durability of chemically modified wood and preservative-treated wood, including treated products, but necessary methods for representative sampling and testing are lacking. Instead of sampling from products that can contain areas of varying durability, this study aimed at testing full-size products. Sections of untreated and preservative-treated terrace decking and palisades were incubated with pure cultures of brown and white rot fungi. Instead of mass loss, the decayed cross-sectional area was determined. The spatial distribution of decay and wood moisture content was investigated. After 16 weeks of incubation, all untreated product specimens showed signs of decay independent of the test fungus. The treated specimens were less affected. The mean and the maximum decayed cross-sectional areas were well correlated, for both the total and the sapwood cross-sections. The wood moisture content after incubation was always favorable for fungal decay, but highest where the specimens were in direct contact with the malt agar. Different infestation pathways became evident: (1) from the sapwood mantle, (2) via radial checks, and (3) from the end-grain. The latter should be prevented in order to better mimic real outdoor exposure conditions.

Influence of storage period on the quality indicators of Astragalus falcatus Lam. seed

Seed storage is the final stage of the technological process of its production, the purpose of which is to ensure the preservation of seed quality from its collection to use. At the same time, the loss of seeds in the process of storage of sowing conditions can cause significant losses both to the direct subjects of seed production of medicinal crops and to producers of medicinal raw materials. At the same time, questions regarding the storage terms of the seeds of sickle-leaved astragalus (Astragalus falcatus Lam.) and the rates of their loss of sowing conditions during storage remain insufficiently defined. The aim of our research was to establish the objective terms of storage of astragalus seeds with maximum preservation of their sowing qualities. The research was conducted for nine years. It was found that the surface gloss is a stable feature for the seeds of astragalus, which was not lost during storage, while the color of the seeds is a relatively unstable feature. During the first two years, no noticeable changes in the color of the seeds were noted. During storage for more than 9 years, the seeds gradually acquired a uniform reddish-brown color from greenish-yellow. The rate of loss of sowing conditions of the seeds of astragalus was determined. Freshly collected seeds were characterized by the maximum germination and hard seed rate, respectively — 84 and 14%. At the same time, the germination energy was 72%. The highest rate of germination energy of few seeds of the second year of storage is 78%. At the same time, the content of hard seeds decreased to 10%, germination decreased to 83%. Therefore, the effect of hard seed on the germination energy indicator is clearly observed, which was 7% lower immediately after harvesting and finishing the seeds compared to the seeds after a year of storage. During four years of storage, the seed germination rate decreased by only 21%, which indicates its gradual loss. The general regularity of the decrease in germination energy is also gradual. Starting from the fifth year of storage, the seeds of the studied sample began to rapidly lose their sowing qualities. Its similarity to the ninth year of storage was only 3%. It was found that the hard seed indicator was completely lost after five years of storage. It was determined that the economic durability of the seeds of the sickle-leaved astragalus is at least four years, and the biological durability lasts for nine years.

Surface carbonization of wood: comparison of the biological performance of Pinus taeda and Eucalyptus bosistoana woods modified by contact charring method

ABSTRACT This study evaluated biological resistance, water absorption, and total carbohydrate contents of carbonized woods by contact charring method followed by linseed oil submersion. Charred and control specimens were exposed in laboratory fungal resistance tests to two white – and two brown-rot fungi and in mold resistance tests by spraying the surface with a mold spore-suspension comprised of three different mold species. Charred and control specimens were also evaluated for resistance to the eastern subterranean termites. To help understand biological durability results, carbohydrate content and water absorption of test specimens were also determined. In all cases, durability against wood degrading fungi increased with the exception of charred Eucalyptus bosistoana wood exposing to the white-rot fungus, Irpex lacteus. Mold resistance of charred Pinus taeda specimens increased considerably when compared to controls however, no mold growth was observed on either control or charred specimens of E. bosistoana. In termite tests, significantly less weight losses were shown in charred specimens of both wood species tested compared to controls although, no complete protection was achieved against termite attack. Total carbohydrate content of charred wood specimens decreased after the carbonization process and as expected, increased hydrophobicity was observed with >50% less water uptake in charred specimens.

Resistance of Cunninghamia lanceolata Wood Against White-rot Fungi by Using Thermo-Mechanical Treatment

Heat treatment is an effective method to enhance the biological durability of wood without the use of preservatives. This study aims to analyze the effect of thermo-mechanical treatment on the durability of wood against the attack of some white rot fungi. The central composite design (CCD) method with the help of Design Expert 12.0 software was used to investigate the effects of temperature, compression time, and compression ratio on the white rot fungus resistance of Cunninghamia lanceolata wood. The obtained results revealed that the thermo-mechanical treatment of Cunninghamia lanceolata samples showed improved antifungal resistance compared to the untreated ones. After 4 months of testing in laboratory conditions, all wood samples with heat-mechanical treatment showed better resistance to fungi. Moreover, the different temperatures, compression ratios, and compression time bring out the different mass loss rates. The obtained results indicate that the wood samples modified at the temperature of 200°C, and 0.6 min/mm thickness combined with the compression ratio ranging from 40÷42% gave the lowest loss rate. Particularly, the resistance test for Lentinula edodes gives the best results when the wood compression time is at 0.7 min/mm thickness. Also, this work would provide a scientific and theoretical basis for the relationship between thermo-mechanical treatment and the biological durability of Cunninghamia lanceolata wood.