Decay and Termite Resistance of Wood Modified by High-Temperature Vapour-Phase Acetylation (HTVPA), a Simultaneous Acetylation and Heat Treatment Modification Process.

High-temperature vapour-phase acetylation (HTVPA) is a simultaneous acetylation and heat treatment process for wood modification. This study was the first investigation into the impact of HTVPA treatment on the resistance of wood to biological degradation. In the termite resistance test, untreated wood exhibited a mass loss (MLt) of 20.3%, while HTVPA-modified wood showed a reduced MLt of 6.6-3.2%, which decreased with an increase in weight percent gain (WPG), and the termite mortality reached 95-100%. Furthermore, after a 12-week decay resistance test against brown-rot fungi (Laetiporus sulfureus and Fomitopsis pinicola), untreated wood exhibited mass loss (MLd) values of 39.6% and 54.5%, respectively, while HTVPA-modified wood exhibited MLd values of 0.2-0.9% and -0.2-0.3%, respectively, with no significant influence from WPG. Similar results were observed in decay resistance tests against white-rot fungi (Lenzites betulina and Trametes versicolor). The results of this study demonstrated that HTVPA treatment not only effectively enhanced the decay resistance of wood but also offered superior enhancement relative to separate heat treatment or acetylation processes. In addition, all the HTVPA-modified wood specimens prepared in this study met the requirements of the CNS 6717 wood preservative standard, with an MLd of less than 3% for decay-resistant materials.

Characterization and Prediction of Physical Properties of Luanta Fir Wood with Vacuum Hydrothermal Treatment.

This study used the luanta fir (Cunninghamia konishii Hayata) wood, one of the most used wood construction and building materials in Taiwan, as specimens to examine the impact of different conditions of vacuum hydrothermal (VH) treatment on the physical properties of this wood. A prediction model for these properties was created using a nondestructive spectroscopy technique. The test results revealed that the mass loss, moisture exclusion efficiency, anti-swelling efficiency, color difference, and surface contact angle of the VH-treated wood all increased under increasing heat treatment temperature and time. Moreover, the use of near-infrared (NIR) spectroscopy in creating the prediction model for the physical properties of the VH-treated luanta fir wood revealed that the ratios of performance to deviation (RPD) for mass loss, equilibrium moisture content, and color difference were all above 2.5, indicating a high prediction accuracy. These results suggested that an NIR spectrometer can serve as a useful instrument for the accurate prediction of the physical properties or for controlling the quality of VH-treated wood.

Characterization and Prediction of Mechanical and Chemical Properties of Luanta Fir Wood with Vacuum Hydrothermal Treatment.

Since the chemical composition of wood is closely related to its mechanical properties, chemical analysis techniques such as near-infrared (NIR) spectroscopy provide a reasonable non-destructive method for predicting wood strength. In this study, we used NIR spectra with principal component analysis (PCA) to reveal that vacuum hydrothermal (VH) treatment causes degradation of hemicellulose as well as the amorphous region of cellulose, resulting in lower hydroxyl and acetyl group content. These processes increase the crystallinity of the luanta fir wood (Cunninghamia konishii Hayata), which, in turn, effectively increases its compressive strength (σc,max), hardness, and modulus of elasticity (MOE). The PCA results also revealed that the primary factors affecting these properties are the hemicellulose content, hydroxyl groups in the cellulose amorphous region, the wood moisture content, and the relative lignin content. Moreover, the ratios of performance deviation (RPDs) for the σc,max, shear strength (σs,max), hardness, and modulus of rupture (MOR) models were 1.49, 1.24, 1.13, and 2.39, indicating that these models can be used for wood grading (1.0 < RPD < 2.5). Accordingly, NIR can serve as a useful tool for predicting the mechanical properties of VH-treated wood.

Comparison of the Physico-Mechanical and Weathering Properties of Wood-Plastic Composites Made of Wood Fibers from Discarded Parts of Pomelo Trees and Polypropylene.

The purpose of this study is to compare the characteristics of wood-plastic composites (WPCs) made of polypropylene (PP) and wood fibers (WFs) from discarded stems, branches, and roots of pomelo trees. The results show that the WPCs made of 30-60 mesh WFs from stems have better physical, flexural, and tensile properties than other WPCs. However, the flexural strengths of all WPCs are not only comparable to those of commercial wood-PP composites but also meet the strength requirements of the Chinese National Standard for exterior WPCs. In addition, the color change of WPCs that contained branch WFs was lower than that of WPCs that contained stem or root WFs during the initial stage of the accelerated weathering test, but the surface color parameters of all WPCs were very similar after 500 h of xenon arc accelerated weathering. Scanning electron microscope (SEM) micrographs showed many cracks on the surfaces of WPCs after accelerated weathering for 500 h, but their flexural modulus of rupture (MOR) and modulus of elasticity (MOE) values did not differ significantly during weathering. Thus, all the discarded parts of pomelo trees can be used to manufacture WPCs, and there were no significant differences in their weathering properties during 500 h of xenon arc accelerated weathering.

Proteomics Reveals Octyl Gallate as an Environmentally Friendly Wood Preservative Leading to Reactive Oxygen Species-Driven Metabolic Inflexibility and Growth Inhibition in White-Rot Fungi (Lenzites betulina and Trametes versicolor).

The most commonly applied wood preservatives are based on creosote, pentachlorophenol, and waterborne chromate copper arsenate, which negatively affect the environment. Thus, environmentally friendly wood preservatives are required. This study investigated the antifungal activity and mechanism of several long-chain alkyl gallates (3,4,5-trihydroxybenzoates) against white-rot fungi, Lenzites betulina and Trametes versicolor. The results revealed that octyl gallate (OG) had the best antifungal activity. Additionally, OG may have a mechanism of action similar to surfactants and inhibit ATPase activity, causing mitochondrial dysfunction and endogenous reactive oxygen species (ROS) production. Upon exposure to endogenous ROS, cells rapidly inhibit the synthesis of 60S ribosomal subunits, thus reducing the mycelial growth rate. L. betulina and T. versicolor also remodeled their energy metabolism in response to low ATP levels and endogenous ROS. After OG treatment, ATP citrate synthase activity was downregulated and glycolytic activity was upregulated in L. betulina. However, the activity of aerobic pathways was decreased and the oxidative branch of the pentose phosphate pathway was redirected form nicotinamide adenine dinucleotide phosphate (NADPH) to minimize endogenous ROS-mediated damage in T. versicolor. Taken together, these observations reveal that OG is a potent inhibitor of white-rot fungus. Further structural optimization research and pharmacological investigations are warranted.

Effects of Acetylated Veneer on the Natural Weathering Properties of Adhesive-Free Veneer Overlaid Wood‒Plastic Composites.

The purpose of this study is to investigate the natural weathering properties of unmodified and acetylated veneer overlaid wood‒plastic composites (vWPCs) manufactured by one-step hot press molding. The results show that the water absorption and thickness swelling of vWPC with acetylated veneer were lower than those of unmodified vWPC. In addition, the surface tensile strength of vWPC increased with increasing weight gain of acetylated veneer, and the flexural properties of vWPC were not significantly different. Furthermore, the results of natural weathering demonstrated that not only the photostability but also the modulus of elasticity (MOE) retention ratio and surface tensile strength of vWPC with acetylated veneer were significantly higher than those of vWPC with unmodified veneer. Thus, better dimensional stability, surface tensile strength, and weathering properties can be achieved when the vWPC is made with acetylated veneer, especially those containing veneers with a higher weight percent gain.

Preparation of Biomorphic Porous SiC Ceramics from Bamboo by Combining Sol-Gel Impregnation and Carbothermal Reduction.

This study investigated the feasibility of using bamboo to prepare biomorphic porous silicon carbide (bio-SiC) ceramics through a combination of sol-gel impregnation and carbothermal reduction. The effects of sintering temperature, sintering duration, and sol-gel impregnation cycles on the crystalline phases and microstructure of bio-SiC were investigated. X-ray diffraction patterns revealed that when bamboo charcoal-SiO2 composites (BcSiCs) were sintered at 1700 °C for more than 2 h, the resulting bio-SiC ceramics exhibited significant ß-SiC diffraction peaks. In addition, when the composites were sintered at 1700 °C for 2 h, scanning electron microscopy micrographs of the resulting bio-SiC ceramic prepared using a single impregnation cycle showed the presence of SiC crystalline particles and nanowires in the cell wall and cell lumen of the carbon template, respectively. However, bio-SiC prepared using three and five repeated cycles of sol-gel impregnation exhibited a foam-like microstructure compared with that prepared using a single impregnation cycle. Moreover, high-resolution transmission electron microscopy and selected area electron diffraction revealed that the atomic plane of the nanowire of bio-SiC prepared from BcSiCs had a planar distance of 0.25 nm and was perpendicular to the (111) growth direction. Similar results were observed for the bio-SiC ceramics prepared from bamboo-SiO2 composites (BSiCs). Accordingly, bio-SiC ceramics can be directly and successfully prepared from BSiCs, simplifying the manufacturing process of SiC ceramics.

Long-Term Creep Behavior Prediction of Sol-Gel Derived SiO2- and TiO2-Wood Composites Using the Stepped Isostress Method.

In this study, methyltrimethoxysilane (MTMOS), methyltriethoxysilane (MTEOS), tetraethoxysilane (TEOS), and titanium(IV) isopropoxide (TTIP) were used as precursor sols to prepare wood-inorganic composites (WICs) by a sol-gel process, and subsequently, the long-term creep behavior of these composites was estimated by application of the stepped isostress method (SSM). The results revealed that the flexural modulus of wood and WICs were in the range of 9.8-10.5 GPa, and there were no significant differences among them. However, the flexural strength of the WICs (93-103 MPa) was stronger than that of wood (86 MPa). Additionally, based on the SSM processes, smooth master curves were obtained from different SSM testing parameters, and they fit well with the experimental data. These results demonstrated that the SSM was a useful approach to evaluate the long-term creep behavior of wood and WICs. According to the Eyring equation, the activation volume of the WICs prepared from MTMOS (0.825 nm3) and TEOS (0.657 nm3) was less than that of the untreated wood (0.832 nm3). Furthermore, the WICs exhibited better performance on the creep resistance than that of wood, except for the WICMTEOS. The reduction of time-dependent modulus for the WIC prepared from MTMOS was 26% at 50 years, which is the least among all WICs tested. These findings clearly indicate that treatment with suitable metal alkoxides could improve the creep resistance of wood.

Nonisothermal Crystallization Kinetics of Acetylated Bamboo Fiber-Reinforced Polypropylene Composites.

The crystallization behavior of bamboo fiber (BF) reinforced polypropylene (PP) composites (BPCs) was investigated using a differential scanning calorimeter (DSC). The results showed that unmodified BF as a nucleation agent accelerated the crystallization rate of the PP matrix during cooling whereas there is no significant effect on the improved crystallization rate in BPCs with acetylated BFs. Based on the Avrami method, Avrami-Ozawa method, and Friedman method, the corresponding crystallization kinetics of PP reinforced with different acetylation levels of BFs were further analyzed. The results demonstrated that the crystal growth mechanism of the PP matrix for BPCs with unmodified and various acetylated BFs exhibited tabular crystal growth with heterogeneous nucleation. A higher cooling rate is required to achieve a certain relative crystallinity degree at the unit crystallization time for BPCs with a higher weight percent gain (WPG) of acetylated BFs (WPG >13%). Furthermore, based on the Friedman method, the lowest crystallization activation energy was observed for the BPCs with 19% WPG of acetylated BFs.

The Effect of Maleated Polypropylene on the Non-Isothermal Crystallization Kinetics of Wood Fiber-Reinforced Polypropylene Composites.

The influence of maleated polypropylene (MAPP) on the non-isothermal crystallization behavior of wood fiber (WF)-reinforced PP composites (WPCs) was investigated by a differential scanning calorimeter (DSC). The results showed that MAPP as a nucleation agent accelerated the crystallization rate of the PP matrix in WPC under the cooling process. The corresponding crystallization kinetics and activation energy were further analyzed using the Avrami method, Avrami⁻Ozawa method, Kissinger method, and Friedman method. The results demonstrated that MAPP significantly changed the crystal growth mechanism of the PP matrix to heterogeneous nucleation for acicular and tabular crystal growth during the annealing step. A remarkably lower cooling rate can achieve a certain relative crystallinity degree at the unit crystallization time for WPC with 3 wt % MAPP (WPCM3). Similarly, the lowest crystallization activation energy was observed for the WPCM3 among all WPCs by the Kissinger method. Furthermore, based on the Friedman method, the addition of MAPP easily caused the PP matrix to crystallize in the WPC at the initial stage of relative crystallinity.

Effect of SiO2 Content on the Extended Creep Behavior of SiO2-Based Wood-Inorganic Composites Derived via the Sol⁻Gel Process Using the Stepped Isostress Method.

In this study, methyltrimethoxysilane (MTMOS) was used as a reagent to prepare SiO2-based wood-inorganic composites (WICSiO2) via the sol-gel process, and subsequently, the extended creep behaviors of WICSiO2 with weight percent gains (WPGs) of 10%, 20%, and 30% were estimated using the stepped isostress method (SSM). The results revealed that the density of all samples ranged from 426 to 513 kg/m³, and no significant difference in the modulus of elasticity (MOE) was noted among all of the samples (10.5⁻10.7 GPa). However, the MOR of WICSiO2 with a WPG of 20% (102 MPa) was significantly greater than that of untreated wood (87 MPa). In addition, according to the result using the SSM, the SSM-predicted creep master curve fitted well with the experimental data for the untreated wood and WICSiO2. This result demonstrated that the SSM could be a useful method to evaluate long-term creep behaviors of wood and WICSiO2. Furthermore, the activation volume (V*) of the specimens was calculated from the linear slope of Eyring plots, and the resulting V* of all of the WICSiO2 (0.754⁻0.842 nm³) was lower than that of untreated wood (0.856 nm³). On the other hand, the modulus reduction of untreated wood showed 39%, 45%, 48%, and 51% at 5, 15, 30, and 50 years, respectively. In contrast, the modulus reduction of the WICSiO2 with a WPG of 10% decreased to 25%, 31%, 35%, and 38% at 5, 15, 30, and 50 years, respectively. Similar trends were also observed for other WICSiO2 with different WPGs. Of these, the WICSiO2 with a WPG of 20% exhibited the lowest reduction in time-dependent modulus (31%) over a 50-year period. Accordingly, the creep resistance of the wood could be effectively enhanced under the MTMOS treatment.

Effects of Heat-Treated Wood Particles on the Physico-Mechanical Properties and Extended Creep Behavior of Wood/Recycled-HDPE Composites Using the Time-Temperature Superposition Principle.

This study investigated the effectiveness of heat-treated wood particles for improving the physico-mechanical properties and creep performance of wood/recycled-HDPE composites. The results reveal that the composites with heat-treated wood particles had significantly decreased moisture content, water absorption, and thickness swelling, while no improvements of the flexural properties or the wood screw holding strength were observed, except for the internal bond strength. Additionally, creep tests were conducted at a series of elevated temperatures using the time-temperature superposition principle (TTSP), and the TTSP-predicted creep compliance curves fit well with the experimental data. The creep resistance values of composites with heat-treated wood particles were greater than those having untreated wood particles due to the hydrophobic character of the treated wood particles and improved interfacial compatibility between the wood particles and polymer matrix. At a reference temperature of 20 °C, the improvement of creep resistance (ICR) of composites with heat-treated wood particles reached approximately 30% over a 30-year period, and it increased significantly with increasing reference temperature.

Characterization and Thermal Stability of Acetylated Slicewood Production by Alkali-Catalyzed Esterification.

This study was compared and characterized two different alkali (potassium carbonate (PC) and potassium acetate (PA))-catalyzed acetylations of slicewood with vinyl acetate (VA) by a vapor phase reaction. The results revealed that the esterification reaction between VA and the hydroxyl groups of slicewood could be improved by using PC or PA as a catalyst. Additionally, a significant weight percent gain was obtained after VA acetylation with 5% of catalyst. Furthermore, the reactivity of the cellulose hydroxyl groups for VA acetylation was more pronounced at the C2 reactive site compared to acetylation with acetic anhydride. On the other hand, the apparent activation energy of thermal decomposition between 10% and 70% conversion is 174-183, 194-200, and 183-186 kJ/mol for unmodified slicewood and VA-acetylated slicewood with PC and PA, respectively. Accordingly, the thermal stability of the slicewood could be effectively enhanced by VA acetylation, especially for using the PC as a catalyst.

Characterization of Wood-Plastic Composites Made with Different Lignocellulosic Materials that Vary in Their Morphology, Chemical Composition and Thermal Stability.

In this study, four kinds of lignocellulosic fibers (LFs), namely, those from Chinese fir (Cunninghamia lanceolata), Taiwan red pine (Pinus taiwanensis), India-charcoal trema (Trema orientalis) and makino bamboo (Phyllostachys makinoi), were selected as reinforcements and incorporated into high-density polyethylene (HDPE) to manufacture wood-plastic composites (WPCs) by a flat platen pressing process. In addition to comparing the differences in the physico-mechanical properties of these composites, their chemical compositions were evaluated and their thermal decomposition kinetics were analyzed to investigate the effects of the lignocellulosic species on the properties of the WPCs. The results showed that the WPC made with Chinese fir displayed a typical M-shaped vertical density profile due to the high aspect ratio of its LFs, while a flat vertical density profile was observed for the WPCs made with other LFs. Thus, the WPC made with Chinese fir exhibited higher flexural properties and lower internal bond strength (IB) than other WPCs. In addition, the Taiwan red pine contained the lowest holocellulose content and the highest extractives and α-cellulose contents, which gave the resulting WPC lower water absorption and flexural properties. On the other hand, consistent with the flexural properties, the results of thermal decomposition kinetic analysis showed that the activation energy of the LFs at 10% of the conversion rate increased in the order of Taiwan red pine (146⁻161 kJ/mol), makino bamboo (158⁻175 kJ/mol), India-charcoal trema (185⁻194 kJ/mol) and Chinese fir (194⁻202 kJ/mol). These results indicate that the morphology, chemical composition and thermal stability of the LFs can have a substantial impact on the physico-mechanical properties of the resulting WPCs.

Comparison and characterization of the antioxidant potential of 3 wild grapes--Vitis thunbergii, V. flexuosa, and V. kelungeusis.

UNLABELLED: This study considers a laboratory examination of the antioxidant performance of methanolic extracts from the leaves and stems of 3 common wild grapes (Vitis thunbergii, V. flexuosa, and V. kelungeusis) by various in vitro methods. It also seeks to identify the specific antioxidant constituent. Results revealed that, of these specimens, stem extracts of V. thunbergii exhibited good 1,1-diphenyl-2-picrylhydrazyl radical-scavenging and superoxide radical-scavenging performance and ferrous ion-chelating ability, as well as the highest total phenolic content (179.5 mg of GAE/g). The principal antioxidant, (+)-lyoniresinol-2a-O-ß-D-glucopyranoside, was isolated from the stem extracts of V. thunbergii and identified. Removal of this compound from the extracts caused an approximate 2- to 5-fold decrease in antioxidant performance. This showed that (+)-lyoniresinol-2a-O-ß-D-glucopyranoside is the primary antioxidant in wild grapes. Results also indicated that the antioxidant performance of (+)-lyoniresinol-2a-O-ß-D-glucopyranoside was stronger than its lignan aglycone, (+)-lyoniresinol. PRACTICAL APPLICATION: Of the 3 common wild grapes-Vitis thunbergii, V. flexuosa, and V. kelungeusis, the extracts or phytochemicals, derived from the V. thunbergii stems have excellent antioxidant properties, so they have great potential as a basis for natural health products that seek to prevent diseases caused by the overproduction of radicals.