Poor Dimensional Stability Research Articles

Highly Flexible Electrodes Based on Nano/Micro‐Fiber for Flexible Lithium Metal Batteries

AbstractAlthough Li metal batteries (LMBs) with high flexibility are attractive energy storage systems for wearable devices due to their high energy density, there exist critical challenges such as limited loading density, poor dimensional stability, and thus mechanical instability under repeated mechanical deformations including bending, twisting, and folding. In this work, extremely flexible nano/microfiber composite electrodes are developed for LMBs. The highly flexible and mechanically durable electrode is composed of oxidized polyethylene terephthalate (O‐PET) microfiber (MF) substrates covered by single‐walled carbon nanotube (CNT) nanofibers (NF), prepared by mass‐producible O2 plasma treatment and spray‐coating. CNT nanofibers provided an electrical intertangled network to integrate the active materials (i.e., either NCM or passivated Li powder (PLP)) and anchored to a flexible O‐PET MF substrate, which permits high mass loading of active materials, improved electrochemical performance while maintaining mechanical durability. Resultantly, the flexible LMBs based on nano/micro fibrous electrodes have excellent energy density (300.1 Wh kg−1 electrode; nominal voltage of 3.7 V) and stable capacity retention (97.1%) without mechanical failure over 500 folding cycles.

Effect of Polyethylene Glycol with Different Molecular Weights on the Properties of Mytilaria laosensis Timber

Mytilaria laosensis, a common fast-growing tree species in southern China, boasts excellent growth speed and attractive color and texture. However, due to its short growth cycle and high proportion of juvenile wood, it typically exhibits poor dimensional stability and low strength, which significantly limits its practical applications. This study uses vacuum impregnation to modify M. laosensis wood with polyethylene glycol (PEG), focusing on the effects and mechanisms of PEG with different molecular weights on wood properties. The results indicate that PEG enters the wood cell walls through capillary action and diffusion, forming hydrogen bonds with the free hydroxyl groups on cellulose and hemicellulose, which keeps the cell walls swollen and enhances dimensional stability. Post modification, the dimensional stability of M. laosensis wood improved, with an anti-swelling efficiency ranging from 61.43% to 71.22%, showing an initial increase followed by a decrease with increasing PEG molecular weight. The optimal PEG molecular weight for anti-swelling efficiency was 1500 Da, achieving 71.22%. The flexural modulus of elasticity and flexural strength of the treated wood also first decreased and then increased with increasing PEG molecular weight. Among them, the PEG1000-treated material showed the best performance, with the flexural modulus of elasticity increased by about 29% and the flexural strength increased by about 5% compared to untreated wood. Additionally, PEG, having a higher pyrolysis temperature than wood, raised the initial pyrolysis temperature and maximum pyrolysis rate temperature of M. laosensis wood, thus improving its thermal stability. These findings provide scientific evidence and technical support for the efficient utilization and industrialization of M. laosensis wood, promoting its widespread application and industrial development.

Preparation of dimensionally stable and strong thin-type bamboo bundle laminated veneer lumber through delignification and phenolic resin synergies

The development of thin-type bamboo bundle laminated veneer lumber (T-BLVL) represents a significant advancement in environmentally friendly and sustainable building materials. However, the application of T-BLVL is still hindered by poor dimensional stability and low mechanical strength. In this study, the delignified thin-type bamboo bundle laminated veneer lumber (D-T-BLVL) was prepared through the partial delignification of bamboo bundles and the synergistic effects of phenolic resin (PF). These effects included gluing, strengthening, and waterproofing. D-T-BLVL exhibited high strength, dimensional stability, and a remarkable thickness of only 5 mm. After the removal of 26 % lignin, the porosity of bamboo bundles increased by 117 % compared with natural bamboo bundles, facilitating enhanced PF infiltration. D-T-BLVL exhibited a bending strength of 281.84 MPa, representing an 83.75 % increase over that of T-BLVL (153.38 MPa). Additionally, the water absorption thickness expansion rate of D-T-BLVL (3.37 %) was only approximately 1/4 times that of T-BLVL (13.30 %). The development of D-T-BLVL provides valuable guidance for developing wind turbines, infrastructures, and other advanced technologies.

A clean, simple, and efficient method for preparing vibration-reducing low-carbon bamboo building materials with high strength

Large-format bamboo panels prepared by bamboo flattening are adhesive-free and retain the natural structure of bamboo, making them ideal materials for interior architecture. However, due to poor dimensional stability and vibration-reducing properties, flattened bamboo easily deforms and vibrates when applied to building walls and floors due to ambient humidity changes or external excitation, impacting both comfort and structural safety. In this work, a clean, efficient, and simple densification process for flattened bamboo is developed to prepare low-carbon bamboo building materials with enhanced vibration reduction. The results indicated that the densification process reduced the vibration intensity of the flattened bamboo under excitation, changed its vibrational modes, avoided low-frequency resonance, and improved its vibration reduction and suppression properties. The dynamic stiffness of the densified bamboo increased to 3.23–3.63 times, while the root mean square (RMS) and transfer function value decreased by 20.84 % and 62.5 %, respectively. The MOE (16.2 GPa) and MOR (276 MPa) increased to 2.73 times and 2.22 times, respectively. The densified bamboo met the dimensional stability requirements of the GB/T 18102–2020 building material standards. Compared with damping, the increased stiffness played the primary role in improving the vibration-reducing properties of densified bamboo. The hydrothermal mechanical treatment changed the structure and composition. From a macroscopic perspective, the gradient structure of the vascular bundles and parenchyma cells was gradually plasticized and homogenized, compacting large capillary pores and channels such as those in parenchyma cells, vessels, and sieve tubes. On a microscopic level, defects such as pits, intercellular spaces, and micropores were filled, and microfibrils between the middle lamellae were tightly stacked, forming a mechanically-interlocked structure. At the molecular scale, there was an increase in the crystallinity and orientation of cellulose molecular chains, accompanied by an increase in hydrogen bond density. The densified bamboo developed in this study shows good application potential for vibration-reduction structures such as buildings and rail transit.

Dimensionally stable and durable wood by lignin impregnation

Cracking, warping, and decaying stemming from wood's poor dimensional stability and durability are the most annoying issues of natural wood. There is an urgent need to address these issues, of which, sustainable and green chemical treatments are favorably welcomed. Herein, we developed a facile method through the incorporation of environmentally friendly biopolymer lignin into wood cells for wood dimensional stability and durability enhancement. Enzymatic hydrolysis lignin (EHL) was dissolved into various solvents followed by impregnation and drying to incorporate lignin into wood cells. Impregnation treatment was developed to incorporate into wood to improve its dimensional stability, durability, and micromechanics. The anti-swelling efficiency reached up to 99.4 %, the moisture absorption decreased down to 0.55 %, the mass loss after brown rot decay decreased to 7.22 %, and the cell wall elasticity as well as hardness increased 8.7 % and 10.3 %, respectively. Analyses acquired from scanning electron microscopy, fluorescent microscopy, and Raman imaging revealed that the EHL was successfully colonized in cell lumen as well as in cell walls, thus improved wood dimensional stability and durability. Moreover, Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy confirmed EHL interaction with the cell wall components, thus the wood mechanical property was not impaired significantly, whereas nanoindentation data indicated even slight mechanical enhancement on the cell walls. This facile approach can improve the wood properties in multiple aspects and remarkably enhance the outdoor performance of modified wood products. In addition, using lignin as a natural modifying agent to improve wood performance will have a great positive impact on the environment.

Developing poplar wood into a green structure-decoration integrated material for prefabricated wooden building application

Fast growing poplar wood poses significant challenges including low mechanical strength, poor dimensional stability and weak texture, limiting its direct application in the field of building structures and decoration. We treated poplar wood using compression, digital printing and waterproofing techniques to develop a green structure-decoration integrated material. The compression treatment significantly improved the wood density, fiber orientation and surface smoothness. At a compression ratio of 60 %, poplar veneer demonstrates remarkable improvements in modulus of elasticity (MOE), modulus of rupture (MOR) and surface smoothness, with increases of 222.53 %, 233.53 % and 93.20 %, respectively, compared to uncompressed wood. Notably, this compression treatment reduces the surface roughness of poplar to 0.75 μm, meeting the flatness requirements for digital printing. Consequently, clear textures and vibrant colors are directly printed onto the flat surface of compression-densified poplar wood, eliminating the need for traditional surface sanding pre-treatment process, and accordingly improving the efficiency of the material preparation. Furthermore, a final waterproofing emulsion spraying treatment creates a dense micro/nanoscale hierarchical structure on the surface, enabling the compression-densified poplar wood samples to achieve MOE and MOR of 14.15 GPa and 123.00 MPa respectively, even after water absorption and re-dried processes. These values consistently exceed the standard value of MOE (12.50 GPa) and MOR (35.00 MPa) for the highest grade (TCT40) specified in GB50005-2017, indicating significantly improved structural stability. The structure-decoration integrated materials developed in this study offer high strength and dimensional stability, making them promising candidates for high value utilization in prefabricated wooden buildings.

Use of Limestone Sludge in the Preparation of ɩ-Carrageenan/Alginate-Based Films.

The use of processed limestone sludge as a crosslinking agent for films based on Na-alginate and ɩ-carrageenan/Na-alginate blends was studied. Sorbitol was tested as a plasticizer. The produced gel formulations included alginate/sorbitol and carrageenan/alginate/sorbitol mixtures, with tested sorbitol concentrations of 0.0, 0.5 and 1.0 wt%. The limestone sludge waste obtained from the processing of quarried limestone was converted into an aqueous solution of Ca2+ by dissolution with mineral acid. This solution was then diluted in water and used to induce gel crosslinking. The necessity of using sorbitol as a component of the crosslinking solution was also assessed. The resulting films were characterized regarding their dimensional stability, microstructure, chemical structure, mechanical performance and antifungal properties. Alginate/sorbitol films displayed poor dimensional stability and were deemed not viable. Carrageenan/alginate/sorbitol films exhibited higher dimensional stability and smooth and flat surfaces, especially in compositions with 0.5 wt% sorbitol. However, an increasing amount of plasticizer appears to result in severe surface cracking, the development of a segregation phenomenon affecting carrageenan and an overall decrease in films' mechanical resistance. Although further studies regarding film composition-including plasticizer fraction, film optimal thickness and film/mold material interaction-are mandatory, the attained results show the potential of the reported ɩ-carrageenan/alginate/sorbitol films to be used towards the development of viable films derived from algal polysaccharides.

Enhancing Cross-Linking Network for Superior Wet Strength of Paper by Sustainable Hyperbranched Polyimines.

The paper industry has long been a crucial part of our lives, providing printing materials, tissue paper, and packaging products. However, the low wet strength of commercially available paper limits its application in packaging, particularly when it comes into contact with liquids. To address this issue, researchers have explored various strategies, including the use of wet strength agents. The most widely used agent, polyamide-epichlorohydrin resin (PAE), has limitations, such as poor dimensional stability and limited recyclability. Additionally, PAE can release harmful chlorinated organics. To overcome these challenges, we report a novel approach using a hyperbranched wet strength agent (referred to as "OA-PI") based on the cross-linking of oxidized amylopectin from waxy corn and polyamines through the Schiff base reaction. The hyperbranched structure of OA-PI provides multiple binding sites, enhancing the cross-linking strength of cellulosic paper under wet conditions. The paper treated with OA-PI exhibited exceptional wet strength, significantly higher than that of PAE-treated paper and paper with traditional starch-based additives. Moreover, the biomass-based OA-PI showed improved recyclability and reduced harm from chlorinated organic compounds. This study not only enhances the wet strength of paper but also opens sustainable avenues for the design of functional adhesives.

Chemical Composition and FTIR Analysis of Acetylated Turkey Oak and Pannonia Poplar Wood

In this research, acetylation was applied under industrial conditions to improve the properties of Turkey oak and Pannonia poplar wood. Both species are potential “climate winners” in Hungary, yet they are currently underused due their low durability and poor dimensional stability. The acetylation modification process may be a suitable method to improve their properties. In order to verify the effectiveness of the process, comparative chemical analyses (cellulose, hemicelluloses, lignin, extractives, ash, buffering capacity, and pH) of the untreated and acetylated heartwood and sapwood were carried out for both species for the first time. Diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy was also used to support the evaluation of the chemical analyses. The weight percent gain was 11.54% for poplar and 0.94% for Turkey oak, indicating poor treatment efficiency for the latter. The cellulose, hemicelluloses, and lignin contents changed significantly in poplar, with the highest change (+81%) induced by acetylating the hemicelluloses. Only the alpha-cellulose content decreased significantly in Turkey oak, presumably due to the degradation of the non-crystalline part of the cellulose. Acetylation may improve the resistance of Pannonia poplar against moisture, weather, decay, and wood-boring insects, but the process parameters need to be optimized in order to prevent degradation and discoloration in poplar. Turkey oak was found to be less suitable for acetylation due to its low permeability and tendency to crack.

Epoxy-Acrylic Polymer In-Situ Filling Cell Lumen and Bonding Cell Wall for Wood Reinforcement and Stabilization.

Under a global carbon-neutralizing environment, renewable wood is a viable alternative to non-renewable resources due to its abundance and high specific strength. However, fast-growing wood is hard to be applied extensively due to low mechanical strength and poor dimensional stability and durability. In this study, epoxy-acrylic resin-modified wood was prepared by forming a functional monomer system with three monomers [glycidyl methacrylate (GMA), maleic anhydride (MAN), and polyethylene glycol-200-dimethylacrylic acid (PEGDMA)] and filling into the wood cell cavity. The results showed that in the case of an optimal monomer system of nGMA:nPEGDMA = 20:1 and an optimal MAN dosage of 6%, the conversion rate of monomers reached 98.01%, the cell cavity was evenly filled by the polymer, with the cell wall chemically bonded. Thus, a bonding strength of as high as 1.13 MPa, a bending strength of 112.6 MPa and an impact toughness of 74.85 KJ/m2 were applied to the modified wood, which presented excellent dimensional stability (720 h water absorption: 26%, and volume expansion ratio: 5.04%) and rot resistance (loss rates from white rot and brown rot: 3.05% and 0.67%). Additionally, polymer-modified wood also exhibited excellent wear resistance and heat stability. This study reports a novel approach for building new environmentally friendly wood with high strength and toughness and good structural stability and durability.

Research Progress of Reinforced Modification of Fast-Growing Wood

The public’s requirements for a high-quality residential environment and the general improvement in ecological safety awareness have made renewable resource wood and products more favored by furniture, construction and other industries. However, on the one hand, the supply of natural forests is extremely limited, and on the other hand, the materials of artificial forests have defects such as low surface strength and poor dimensional stability due to a loose fiber structure, which restricts their promotion as an alternative to high-quality wood. In this paper, based on the mechanism of wood reinforcement, several reinforcement techniques, such as impregnation, compaction and surface modification, which are widely used in industry, are briefly introduced. On this basis, the possibility of impregnation as a pretreatment method, surface modification and densification to enhance wood was prospected. It is expected to provide reference for improving the added value of plantation wood and alleviating the contradiction between wood supply and demand.

Study on the structural and properties of composite films prepared by blending EUL and NBRL

In order to address issues such as poor dimensional stability caused by low modulus and tensile stress of nitrile butadiene rubber latex (NBRL) films, as well as poor wearing comfortability due to its good adhesion to the human skin, and the inability to meet the requirements of medical special occasions due to low tensile and tear strength. A new strategy is proposed to develop the Eucommia ulmoides latex (EUL) by using the emulsion solvent evaporation technique. EUL was then blended into the NBRL, successfully preparing the NBR/EUG composite latex film. As the Eucommia ulmoides gum (EUG) content increased from 0 to 40 %, the crystallinity of the NBR/EUG composite latex film gradually increased from 0 to 10 % or so. The tensile strength increases from 5.17 MPa to 15.94 MPa, the tear strength increases from 22.17 kN/m to 37.79 kN/m, the modulus increases from 6.40 MPa to 24.80 MPa. The very important point is that the elongation at break keep stable with the increase of EUG. On the contrary, the elongation at break will decrease with addition of conventional fillers into the latex, such as silica. These enhance mechanical properties and keep the dimensional stability of the film. Therefore, it can be utilized for the development of latex film products with high modulus and big deformation, such as sky balloon and foam mattress. Additionally, the crystalline nature of EUG effectively reduces the adhesion force on the surface of the composite latex film, thus improving its compatibility with human skins. This meets the requirements of special environments, such as medical gloves. At last, as a kind of biobased latex, it can increase the content of renewable resources and reduce the carbon emission of NBRL.

Solid Polymer Electrolytes with Dual Anion Synergy and Twofold Reinforcement Effect for All-Solid-State Lithium Batteries.

Solid polymer electrolytes (SPEs) have emerged as a viable alternative to traditional organic liquid-based electrolytes for high energy density and safer lithium batteries. Poly(ethylene oxide) (PEO)-based SPEs are considered one of the mainstream SPE materials with excellent dissociation ability of lithium salts. However, the inferior ionic conductivity at room temperature and poor dimensional stability at high temperature limit their utilization. In this work, a semi-interpenetrating polymer network (semi-IPN) forming a precursor based on an ionic liquid (IL) monomer and linear PEO chains were introduced into an electrospun poly(acrylonitrile) (PAN) fibrous mat with subsequent thermal-initiated cross-linking. 1,4-Diazabicyclo [2.2.2] octane (DABCO) and 4-(chloromethyl) styrene were used to synthesize the styrenic-DABCO-based IL monomer with bis(trifluoromethane sulfonyl)imide (TFSI-) or bis(fluoromethane sulfonyl)imide (FSI-) as the anion, named as SDTFSI and SDFSI, respectively. Together, the FSI- and TFSI- anions demonstrate a synergistic effect in providing ion-conductive LiF and Li3N-rich inorganic SEI layer with enhanced lithium dendrite suppression ability. The twofold reinforcement effect is achieved collectively from the semi-IPN structure and the three-dimensional (3D) PAN network that help to construct highly efficient and uniform ion transport channels with excellent flexibility, further suppressing the lithium dendrite growth. The SPEs were dimensionally stable even at elevated temperatures of 150 °C. Moreover, the SPEs show an ionic conductivity of 4.4 × 10-4 S cm-1 at 25 °C and 1.81 × 10-3 S cm-1 at 55 °C and a lithium-ion transference number of 0.56. The favorable electrochemical performance of the SPEs was verified by operating LiFePO4/Li and NMC/Li cells.

Chemical Surface Modification of Cornstarch Microparticles by Acetic Acid for Curcumin Carrier

Starch without further processing has hydrophilic properties, making it have mechanical properties, and poor dimensional stability, especially in moist or water-rich environments. Thus, efforts to modify starch using chemical processes to make hydrophobic starch have been developed. This study aimed to modify and characterize chemically modified corn starch microparticles by acetic acid and their application as curcumin carriers. Corn starch was chemically modified using various concentrations of acetic acid (50, 75, and 99%). In this study, analyses of physicochemical characteristics (such as using Fourier Transform Infrared (FTIR) and Scanning Electron Microscope (SEM)), hydrophobicity/swelling characteristics, loading effectiveness, and loading capacity were performed. Modified corn microparticles showed a surface free of pores. According to the FTIR findings, acetic acid treatment was effective in changing the chemical characteristics of the corn starch surface. Hydrophobicity, loading efficiency, and loading capacity increased with increasing concentration of glacial acetic acid used. This study demonstrates the ability of hydrophobic corn starch microparticles as a carrier for active ingredients such as curcumin. This study can support the current sustainably development goals (SDGs).

Improved balance between dimensional stability, mechanical properties and processability of linear low density polyethylene for rotational molding

AbstractThe linear low density polyethylene (LLDPE) products made by rotational molding (RM) usually involve two main problems of poor dimensional stability and insufficient mechanical properties. Although the decline in thermal expansion coefficient and rise in mechanical strength can be attained by filling with inorganic particles, the melt fluidity of LLDPE, which is of great importance for RM, would be significantly reduced. In this study, a combination of crosslinker low‐temperature blending and partial chemical crosslinking strategy is employed to enhance the dimensional stability and mechanical properties of LLDPE without sacrificing the melt fluidity. The structure–property relationships in the crosslinked specimens are analyzed based on X‐ray diffraction, differential scanning calorimetry, thermogravimetric analysis, scanning electron microscopy, and dielectric spectrometry. The results show that our simple, low‐cost and universal strategy not only contributes to a better dimensional stability and significantly improved mechanical properties, but also endow the samples with promising processability and thermal stability.

Effect of tempering temperature and subzero treatment on microstructures, retained austenite, and hardness of AISI D2 tool steel

The presence of retained austenite in the hardening process of tool steel often causes the lower hardness compared to the hardness requirements and poor dimensional stability in the tool steel. The purpose of the present research is to determine the relationships between the tempering process with and without cryogenic treatment to the hardness and retained austenite amount of as-hardened D2 tool steel. The austenitizing temperature was 1020 °C, the tempering temperatures have variations of 180 °C, 280 °C, 380 °C, 480 °C, and 580 °C, and the subzero treatment has a temperature of −172 °C, followed by tempering at 180 °C, 380 °C, and 580 °C. This study aims to determine the appropriate treatment to obtain a minimum retained austenite percentage to prevent and mitigate the failure of AISI D2 tool steel in the industrial application process. An optical microscope with image processing software (Image-J analysis), as well as Brinell and Vickers hardness testing, is the characterization method used in this work. In general, plate martensite, bainite, retained austenite, and primary and secondary carbides are the phases contained in the microstructure. Tempering temperatures have the effect of increasing the secondary carbide precipitation and decreasing the retained austenite content (γr 3,671%–2,769%). However, the cryogenic treatment can provide a more efficient martensitic phase transformation process and minimal retained austenite content (γr 2,257%–1,199%). The increase in tempering temperature causes a decrease in hardness at a temperature of 180 °C–380 °C. On the other hand, the secondary hardening and phase transformation phenomena cause an increase in the hardness of the as-tempered sample at a temperature of 480 °C, before the sample reexperiences a significant decrease in hardness at a temperature of 580 °C due to diffusion that decreases the carbon content.

Increased dimensional stability of Eucalyptus grandis × Eucalyptus urophylla ‘GLGU9’ wood through palm oil thermal treatment

Eucalyptus grandis × Eucalyptus urophylla ‘GLGU9’ is one of the most commonly planted tree species in South China. It is a new variety created by Guangxi Zhuang Autonomous Region Forestry Research Institute. As a fast-growing species, the poor dimensional stability is one of its main drawbacks, which restricts its applications. Thermal treatment is one of the effective methods to improve the dimensional stability of wood. GLGU9 wood was treated using thermal modification with palm oil. The oil was used as a heating medium and a shielding material at temperatures of 150, 170, 190, 200, and 210 °C, at various treatment durations of 1.5, 3, 4.5 and 6 h. To investigate the effect of palm oil thermal treatment on dimensional stability, the anti-shrink efficiency (ASE1) and anti-swelling efficiency (ASE2) were examined. The results indicated that the ASE1 and ASE2 were increased by 62.8% and 56.6% at 210 °C for 6 h treatment, respectively.

Effects of Heat Treatment on Color, Dimensional Stability, Hygroscopicity and Chemical Structure of Afrormosia and Newtonia Wood: A Comparative Study of Air and Palm Oil Medium.

In recent years, China is increasingly dependent on imported wood. Afrormosia and Newtonia are some of the imported species with good utilization potential. However, both of them also have problems with poor dimensional stability. In order to make better use of these two types of wood, the influence of heat treatment under air and palm oil conditions on the color, dimensional stability, and hygroscopicity of Afrormosia and Newtonia was investigated. The Afrormosia and Newtonia wood samples were heated in air or palm oil medium for two hours at 160 °C, 180 °C and 200 °C, respectively. Then, the color, weight changes, swelling, moisture absorption and chemical structure were evaluated for each case. As results, the heat treatments with air or palm oil increased the dark color of Newtonia and Afrormosia wood and this increase was proportional to the treatment temperature. The tangential and radial swelling coefficient for air heat treatment of Afrormosia wood at 200 °C were, respectively, reduced by 24.59% and 19.58%, while this reduction for Newtonia was 21.32% and 14.80%. The heat treatment in palm oil further improved the stability and hygroscopicity of the wood, showing that the Afrormosia samples treated by palm oil at 200 °C underwent a decrease of its tangential and radial swelling coefficient, respectively, by 49.34% and 45.88%, whereas the tangential and radial swelling coefficient of Newtonia treated under the same conditions were reduced by 42.85% and 33.63%, respectively. The heat treatments of Afrormosia and Newtonia samples under air at 200 °C diminished the water absorption by 21.67% and 22.12%. The water absorption of Afrormosia and Newtonia heat-treated under palm oil at 200 °C was reduced, respectively, by 39.40% and 37.49%. Moreover, the FTIR analysis showed the decrease of hydroxyl groups in proportion to the wood treatment temperature.

High-performance wood scrimber prepared by a roller-pressing impregnation method

Wood scrimber is a wood-based composite material with high mechanical strength and large size, which can potentially replace the use of steel and cement in various fields. However, its poor dimensional stability and low flame retardancy limit its use in outdoor construction projects and fire-prone areas. To solve this, here we report a roller-pressing impregnation method to realize the deep penetration of resin using mechanical compression and low-pressure adsorption. Microstructural imaging by SEM and 3D ultra-deep field microscopy shows the phenol formaldehyde(PF) resin distribution of the roller-pressed wood scrimber (R-WS) is deeper and more uniform, which increases the flatness and crystallinity. The R-WS showed greatly improved dimensional stability, with 63 % and 35 % lower thickness swelling rate (TSR) and width swelling rate (WSR) compared with the traditional wood scrimber (T-WS). In terms of flame retardancy, the smoke production rate (SPR) and heat release rate (HRR) of R-WS decreased by 32.7 % and 52 %, respectively. The R-WS at 800 °C formed a dense char that content increased by 20 %, helping to inhibits combustion. The mechanical properties of R-WS were also improved, and the modulus of rupture (MOR), modulus of elasticity (MOE) and short-beam strength (SS) of R-WS increased by 31.2 %, 7.4 %and 26.7 %, respectively. The R-WS suffer toughness failure and wood-to-wood failure under bending and shear scenarios, respectively, indicating that the roller-pressing impregnation treatment enhanced toughness and bonding strength. In addition, the use of a rotating roller is expected to realize the continuous production of the dipping link, saving drying energy consumption and improving production efficiency. These properties are expected to promote the outdoor utilization and continuous production of wood scrimber.

Anion exchange membranes based on poly (styrene‐b‐(ethylene‐co‐butylene)‐b‐styrene) grafted poly (2,6‐dimethyl‐1,4‐phenylene oxide)

AbstractPoly (styrene‐b‐(ethylene‐co‐butylene)‐b‐styrene) (SEBS) has been widely studied in the field of anion exchange membranes (AEMs) due to its superior flexibility and chemical stability, but the poor dimensional stability of functionalized SEBS restricts its further application. Thus, we adopt an effective strategy to reinforce AEMs based on SEBS via grafting poly (2,6‐dimethyl‐1,4‐phenylene oxide) (PPO) using Williamson ether synthesis reaction. With the addition of PPO, grafted membranes exhibit outstanding comprehensive properties, such as mechanical strength, chemical stability, especially dimensional stability. SEBS‐PPO‐QA‐1 grafted membrane with the highest content of PPO showed the best tensile strength (20.54 MPa), and restrained swelling behavior (swelling ratio of 4.81% at 25°C). Moreover, the conductivity retention of SEBS‐PPO‐QA‐1 grafted membrane is up to 92.71% at 80°C after 10 days alkaline treatment. The ion exchange capacity of SEBS‐PPO‐QA‐3 grafted membrane is 1.719 mmol/g, and the ionic conductivity of SEBS‐PPO‐QA‐3 grafted membrane reach 58.27 mS/cm at 80°C and 25.53 mS/cm at 20°C. Therefore, the SEBS‐PPO‐QA‐X grafted membranes, which combine the advantages of PPO and SEBS, are promising in AEM application.