Search

Fiberboards from scrap denim were fabricated using two different resins, melamine urea formaldehyde (MUF) and polymeric methylene diphenyl diisocyanate (pMDI). Resin content and MUF-pMDI weight ratio were studied. Physical and mechanical tests determined the modulus of elasticity (MOE), modulus of rupture (MOR), internal bond (IB), thickness swell (TS), and water absorption (WA). The resin content had significant impact on all properties. The MOE and IB were affected by the MUF-pMDI ratio. With 17 wt% more pMDI resin portion in the core layer of the denim boards, the IB for the denim fiberboard with a resin content of 15% was enhanced by 306%, while by 205% for the resin content of 25%. The increase in pMDI portion in the core layer of the boards improved both TS and WA of the scrap denim fiberboard. Effective bulk modulus elastography (EBME) was used to measure the acoustic reflection for the estimation of the strength properties of the denim fiberboard. The modulus results from EBME were correlated to the MOR, MOE, and IB of the denim fiberboard. A high correlation was found between the modulus from EBME and IB (R2 > 0.98). EBME can be a great technique to evaluate the bulk modulus distribution of the composites. [ABSTRACT FROM AUTHOR]

Recently, soy protein has attracted extensive attention from wood industries and consumers in the production of wood adhesives as it is non‐toxic, biodegradable, low cost, and easy to process. There are a variety of reactive groups namely OH, NH2, COOH, and SH, in protein molecules, which offer possibilities for protein denaturation, chemical modification, and increased ionic interactions. The research in protein denaturation, crosslinking modification, biomimetic modification, and organic–inorganic hybrid formulation not only focuses on enhancing the mechanical properties and tolerance to water of the adhesives but also considers its toughness, mildew resistance, and flame retardancy to further optimize the performances of the adhesives. In this paper, soy protein chemical composition, soy protein denaturation, and reinforced modification are discussed to understand these methods and further develop into a multifunctional soy protein‐based adhesive. Given the potential of bio‐based adhesives, these modification methods not only provide the theoretical basis for its development at full scale, but also the possibility for the multifunctional applications of bio‐based adhesives. [ABSTRACT FROM AUTHOR]

A large quantity of resources consumed by the construction industry and the resultant pollution has inspired the need to study eco-friendly materials, such as kenaf fibers, that can be used for construction applications. Kenaf fibers were used to reinforce cement by fabricating fiber reinforced cement composites that exhibited outstanding mechanical and thermo-physical properties. A considerable interest has arisen in investigating the use of natural fiber to replace synthetic fiber for different composite products to alleviate the environmental impact from the traditional construction materials. In order to evaluate the environmental performances of glass fiber reinforced cement wall panels and kenaf fiber reinforced cement wall panels, this study conducted a comparative life cycle assessment (LCA) on the fiber reinforced cement wall panels between kenaf fiber and traditional glass fiber. The structural function and thermal insulation function of the wall panels were considered as two separate functional units. The LCA results showed that the environmental impact could be significantly reduced using kenaf fiber to replace glass fiber as reinforcement in the cement wall panels in regards to both structural and insulation functions. The major contribution to the environmental impact for the fiber reinforced wall panels was from cement and the production of the cement raw materials. Kenaf fiber significantly reduced environmental impact, which can be a viable eco-friendly material to replace glass fiber for the construction industry. [ABSTRACT FROM AUTHOR]

The kenaf fiber/polyester composites, owning the comparable mechanical properties with commercial glass-fiber sheet molding compounds (SMC) for automotive application, were achieved through the high pressure-assisted magnesium carbonate impregnated fibers and the vacuum-assisted resin transfer molding process. The in situ inorganic nanoparticle impregnation (INI) process was performed by immersing the alkali retted fibers into magnesium chloride solution with various pressures and then treated by sodium carbonate to yield the INI-treated fibers. The magnesium carbonate content was increased by 180.3%, when a 13.79 MPa pressure was applied during the magnesium carbonate immersing process, resulting in lower porosity of fibers. Compared to the un-treated fiber/polyester composite, the mechanical properties of the high pressure-assisted INI-treated fiber/polyester composites were enhanced by 18.6–277.3%, and the 24-h thickness swelling and water absorption were reduced by 64.4% and 62.2%, respectively. The mechanical properties and specific mechanical properties were comparable with or excessed to that of glass-fiber SMC. [ABSTRACT FROM AUTHOR]

Self-activation is a process that takes advantage of the gases emitted from the pyrolysis process of biomass to activate the converted carbon, which saves the cost of activating agents and decreases the environmental impact, compared with conventional activation processes. An activation model was developed to describe the mechanism of the activation process, and it was examined by the self-activation experiments using the kenaf core as a raw material. The relationships among the parameters, yields, specific surface areas, and specific pore volumes were quantified. The results showed that the ideal temperatures for the self-activation process of the kenaf core were found between 970–1090 °C. The yield of 9.0% for the activated carbon from the kenaf core provided the highest surface area per gram of biomass, while the yields of 5.5–13.8% could achieve 90% of the highest. The developed activation model can be used to explain the relationship between the yields, specific surface areas, and specific pore volumes, effectively. [ABSTRACT FROM AUTHOR]

The electromagnetic shielding effectiveness of kenaf fiber based composites with different iron oxide impregnation levels was investigated. The kenaf fibers were retted for removing the lignin and extractives from the fibers and magnetized. Using the unsaturated polyester and the magnetized fibers, kenaf fiber based composites were manufactured by the compression molding process. The transmission energies of the composites were characterized when the composite samples were exposed under the irradiation of electromagnetic (EM) wave with a variable frequency from 9 GHz to 11 GHz. Using the Scanning Electron Microscope (SEM), the iron oxide nanoparticles were observed on the surfaces and inside the micropore structures of single fibers. As the Fe content increased from 0% to 6.8%, 15.9% and 18.0%, the total surface free energy of kenaf fibers with the magnetizing treatments increased from 44.8 mJ/m 2 to 46.1 mJ/m 2 , 48.8 mJ/m 2 and 53.0 mJ/m 2 , respectively, while the modulus of elasticity reduced from 2875 MPa to 2729 MPa, 2487 MPa and 2007 MPa, respectively. Meanwhile, the shielding effectiveness was increased from 30–50% to 60–70%, 65–75% and 70–80%, respectively. [ABSTRACT FROM AUTHOR]

This work was to apply the vacuum-assisted resin infusion (VARI) process and use calcium carbonate inorganic nanoparticle impregnation (INI) to improve the mechanical properties and water resistance of the kenaf fiber/polyester composites. The results show that the modulus of elasticity (MOE), modulus of rapture (MOR), tensile modulus (TE) and tensile strength (TS) of the composites made with INI-treated fibers are increased by 33.1%, 64.3%, 22.3% and 67.8%, respectively, compared with the composites made with un-treated fibers. The thickness swelling of 24-h water submersion is reduced from 19.7% to 1.9%. The moisture contents of the composites after the conditioning and water submersion are reduced from 5.8% to 1.5% and 18.3% to 2.2%, respectively, when INI-treated fibers are employed. The improvement makes the kenaf fiber/polyester composites possible to replace the glass fiber SMC for the automobile application. [ABSTRACT FROM AUTHOR]

Crystallographic structures of carbon-encapsulated iron oxide nanoparticles, derived from the carbonization of cellulose were investigated. The phase transitions of carbon-encapsulated iron oxide nanoparticles were characterized and analyzed after pyrolysis treatment at four temperatures: 500 °C, 800 °C, 1000 °C and 1600 °C, respectively. Transmission Electronic Microscope (TEM) and X-ray diffraction (XRD) techniques were employed for the analysis. Samples treated at 500 °C spontaneously combusted immediately after being exposed to the air indicating the existence of α-Fe 2 O 3 particles. Core-shell structures consisting of dark grains and a light matrix with graphitic structure appeared in samples treated at 800 °C. XRD and TEM selected area electron diffraction demonstrated that between 800 °C and 1600 °C, catalytic graphitization occurred, and the iron carbide/iron crystalline phase was developed for the cores. It was found that the phase transition from Fe 3 C to Fe occurred at 1600 °C. [ABSTRACT FROM AUTHOR]

The effect of external pressure during the inorganic nanoparticle impregnation (INI) process on the content of impregnated calcium carbonate nanoparticles in kenaf fibers was investigated. The in situ INI process was used to introduce the calcium carbonate nanoparticles into the fibers. The retted kenaf fibers were immersed into calcium chloride solution with various pressures and then treated by sodium carbonate solution to produce calcium carbonate nanoparticles impregnated kenaf fibers. It was found that the calcium carbonate content increased by 76.7% when a 13.8 MPa external pressure was applied during the calcium chloride immersing process. The impregnation efficiency for reducing the fiber porosity was increased by 70.1%. The mechanical properties, including modulus of elasticity, modulus of rupture and tensile strength of the INI-treated fiber/polyester composites were enhanced by 43%, 79% and 86% compared with the un-treated fiber/polyester composites. [ABSTRACT FROM AUTHOR]

This work was aimed at applying vacuum-assisted resin transfer molding (VARTM) technique to reinforced polymer molding products made of vegetable fibers. Kenaf ( Hibiscus cannabinus L. Malvaceae) bast fibers were preformed into mat by means of a cold press. The unsaturated polyester resin was infused into the preforms at a vacuum pressure of 1.3-1.6 kPa. The examination of the mechanical properties and microstructure of the prepared composites indicated that the modulus of elasticity (MOE), modulus of rapture (MOR), and tensile strength (TS) of the VARTM composites were increased by 65.5%, 30.7%, and 41.7%, respectively, compared to the traditional hot-pressing composites. The dynamic mechanical analysis (DMA) revealed that the VARTM composite moduli in the temperature range of -50°C-200°C were doubled. The observations by scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and mercury porosimetry confirmed that the interfacial compatibility between the kenaf fibers and the polyester resin was substantially improved. [ABSTRACT FROM AUTHOR]

Rapid population growth and the resultant pollution of freshwater resources have created a water stress condition reducing the availability of safe and affordable water. Guar gum, a biocompatible macromolecule obtained from the endosperm of the seeds of Cyamopsis tetragonolobus , is a fascinating raw material for multifunctional adsorbents. This review assembled the work conducted by various researchers over the past few decades and discussed the structure, properties, and different modifications methods employed to develop versatile guar gum-based adsorbent. The paper also summarized the recent progress of guar gum-based nanocomposites for the remediation of multiple hazardous substances such as organic dyes, toxic heavy metal ions, oil-water separation as well as inhibiting the growth of bacterial pathogens. Thus, the important contribution of guar gum composites to safeguard the water quality is highlighted which will overcome the limitations and streamline the future course of innovative research. • Guar gum (GG)-based materials exhibited versatile applications in water treatment. • Modification and performance of GG-based derivatives are reviewed. • Remediation of dye, metal ions, waterborne pathogens, and oil/water are presented. • Regeneration, trends, and challenges of GG-based nanocomposites are discussed. [ABSTRACT FROM AUTHOR]

The effects of using sodium dodecyl sulfate (SDS) and a modified polyacrylic acid solution (MPA) on a soybean meal adhesive were investigated. Three-ply plywood specimens were fabricated to measure the water resistance of the adhesive (three-cycle soak test). The viscosity and solid content of the adhesive were measured. The cross-section and functional groups of the cured adhesive were evaluated using scanning electron microscope (SEM) and Fourier transform infrared (FTIR) spectroscopy, respectively. The results showed that using SDS improved the water resistance of the soybean meal adhesive by 30%. After incorporating MPA, the water resistance of the soybean meal/SDS/MPA adhesive was further improved by 60%, the viscosity of the adhesive was reduced by 81%, and the solid content of the adhesive increased by 15%. The plywood bonded by the soybean meal/SDS/MPA adhesive met the interior plywood requirements. SEM results showed no holes and cracks on the cross-section of the cured soybean meal/SDS/MPA adhesive. FTIR analysis indicated that more peptide linkages were formed in the cured adhesive as MPA was incorporated. [ABSTRACT FROM AUTHOR]

The effects of a partial hydrolysis treatment on the surface energies of three southern hardwood species, red oak, sweetgum, and yellow-poplar were examined. Miniature beams machined to 3 × 15 × 150 mm (t × r × l) were water-saturated and subjected to a partial hydrolysis at 150°C for 30 min in 1% sulfuric acid, water, or 1% sodium hydroxide solutions. Untreated wood beams were used as controls. Dynamic contact angle specimens were planed from the beams to a thickness of 0.25 mm and cut to a length of 15 mm for analysis via the Wilhelmy plate technique. Surface energies for the wood/treatment combinations were calculated using the geometric mean procedure. Results indicated that acid and water treatments improved the wettability for all species. Alkaline treatment effects were species-specific. All treatments improved the surface energy of red oak. The dispersive forces accounted for the majority of the surface energies. [ABSTRACT FROM AUTHOR]

Wood used in outdoor applications needs to undergo either chemical or thermal treatment to improve its decay resistance. Thermal treatment permits to avoid the use of toxic chemicals, increases the dimensional stability and gives a dark color to the wood. However, this process deteriorates the mechanical properties of wood, i.e., the wood becomes more fragile and rigid. The chemical transformation of wood that takes place during the heat treatment changes the interaction between the wood surface and the adhesive. In this work, the interfacial bonding strength (the resistance to the shear stress by compression in parallel direction to the glued interface) and cyclic delamination (resistance to delamination during accelerated exposure) for different wood species and adhesives were tested in accordance with the ASTM D2559 standard. Four wood species: scott pine (Pinus sylvestris), aspen (Populus tremuloides), yellow poplar (Liriodendron tulipifera) and jack pine (Pinus banksiana) both treated and non-treated, and two structural adhesives, phenol resorcinol formaldehyde (PRF) and polyurethane (PUR), were used in the testing. Among the studied species, jack pine is found to be the easiest to bond, while aspen is found to be the most difficult. With the wood species and adhesives evaluated in this study, non-treated wood is found to provide a better bonding strength than the treated wood. [ABSTRACT FROM AUTHOR]

The contact angle determination on swelling polymer particles by the Washburn equation using column wicking measurements may be problematic because swelling occurs during the wicking process. The objective of this research was to develop a new model to more accurately determine contact angles for polymer particles that undergo solvent swelling during the column wicking process. Two phenomena were observed related to the swelling effect during the wicking process: (1) a temperature rise was detected during the wicking process when the swelling polymer particles interacted with polar liquids, and (2) a smaller average capillary radius (r) was obtained when using methanol (polar liquid) compared to using hexane (non-polar liquid). The particle swelling will induce both particle geometry changes and energy loss which will influence the capillary rise rate. The model developed in this study considered the average pore radius change and the energy loss due to the polymer swelling effect. Contact angle comparisons were conducted on wood with formamide, ethylene glycol, and water as test liquids, determined by both the new model and the Washburn equation. It was shown that the contact angles determined by the new model were about 4-37° lower than those determined by the Washburn equation for water, formamide, and ethylene glycol. Todetermine whether the polymer particles are swelling, two low surface tension liquids, one polar (methanol) and the other non-polar (hexane), can be used to determine the average pore radius (r values) using the Washburn equation. If the same r values are obtained for the two liquids, no swelling occurs, and the Washburn equation can be used for the contact angle calculation. Otherwise, the model established in this study should be used for contact angle determination. [ABSTRACT FROM AUTHOR]

It is known that wood releases low levels of formaldehyde under natural conditions, but the mechanism for this release has not been well explored. This paper presents the lignin-mediated Fenton (LMF) reaction as a newly described mechanism for the generation of formaldehyde from wood lignin in the presence of iron. Traditional desiccator methods with Nash reagent and fluorescence spectrophotometry, and a commercial electrochemical-based formaldehyde sensor were used to examine the effects of important components in the LMF reaction i.e., iron reductant, hydrogen peroxide and lignin, on the wood formaldehyde emission in the presence of iron. The results showed that low levels of iron, especially in its reduced ferrous oxidation state, promoted the generation of formaldehyde in the presence of lignin in wood. Experiments were also conducted with additional iron reductants and hydrogen peroxide, which demonstrated additional formaldehyde generation in the presence of ferric iron and lignin, suggesting active generation of formaldehyde from wood by the LMF reaction. [ABSTRACT FROM AUTHOR]

Bamboo is one of earth's most plentiful natural materials and provides a high-quality alternative to many other raw materials. Utilizing bamboo can help to curtail global warming by decelerating the destruction of forests because it can be a good alternative to wood in its various applications. Bamboo winding composite pipe is a new developed product for water supply application. Life-cycle assessment is a tool used to evaluate the environmental impacts for the use of bamboo in pipes considering all stages of a water pipe's life from raw material extraction to the end of pipe life. In this study, the environmental impacts of polyvinyl chloride pipe and bamboo winding composite pipe were compared using SimaPro (Version 8.5) software. The results demonstrated that, all major indices of environmental impacts (except for the Eutrophication index) were significantly reduced by 1.1–488.8 times when bamboo winding composite pipes were used to replace polyvinyl chloride pipes for the water supply system. In addition, when the bamboo pipe was used to replace the polyvinyl chloride pipe, the cumulative energy demands were reduced by 3.40 times and the total environmental burdens (eco-indicator 99 points) were reduced by 7.19 times. The Building for Environmental and Economic Sustainability index (which is represented by equivalent CO 2 uptake value in SimaPro software) was used to compare the different life cycle stages affecting environments. The results showed that the eq.CO 2 index for the stage of production of bamboo winding composite pipe was 5.35 times of that of the stage of waste pipe disposal/degradation. In addition, the environmental impacts of six raw materials for the bamboo winding composite pipe (per functional unit), i.e., bamboo slivers, modified urea-formaldehyde resin, filling powder of walnut husk, Styrene E, cotton textile and bamboo fiber fabric, were compared using the eq.CO 2 index. It was discovered that the urea-formaldehyde resin, Styrene E and cotton textile took the major parts affecting environment. The sensitivity analysis results indicated that the environmental impacts could be further reduced if 10% Styrene E and urea-formaldehyde was replaced with bamboo slivers. As a conclusion for this study, the major environmental impact indices were significantly reduced when the bamboo winding composite pipe was used to replace polyvinyl chloride pipe. • LCA of bamboo winding pipe and PVC pipe were compared. • Major environmental impact indices were significantly reduced using bamboo pipe. • Environmental burdens of bamboo pipe were reduced by 9.65 times compared to PVC pipe. • Cumulative energy demands of bamboo pipe were reduced by 4.5 times compared to PVC pipe. [ABSTRACT FROM AUTHOR]

To address the limitations of the inability to monitor the internal processing environment of pyrolysis, a triple Gaussian model was developed to effectively describe gas production during biomass pyrolysis at different dwelling temperatures and ramping rates. A CO 2 and H 2 gas sensor array was constructed to collect gas production data during the biomass pyrolysis which was fitted to the three gas production ranges of the triple Gaussian model, carbonization, gasification, and activation. The amplitude A (peak gas production), mean µ (time at gas production peak), and standard deviation σ (rate of gas production) components of the triple Gaussian function were studied for the three ranges. The results showed that as both ramping rate and dwelling temperature increased, the production of CO 2 increased, while the H 2 production decreased. The analysis of A , σ , and μ Gaussian components of the model showed that in the carbonization range, the peak CO 2 increased and H 2 production decreased. In the gasification range, the CO 2 production decreased, while more H 2 production happened as the ramping rate and dwelling temperature increased. The components of both H 2 and CO 2 models were compared. These relationships between Gaussian components and ramping rate and dwelling temperature, showed clear linear trends. The results showed that the carbonization and gasification ranges of the two models were inversed. ESEM was performed on the resulting carbons which showed that more degradation in the carbon structure occurred at higher temperatures and lower ramping rate. [Display omitted] • Wood was pyrolyzed at different temperatures and ramping rates. • The impact of processing parameters on the CO 2 and H 2 production was studied. • Model based on triple Gaussian function was developed to understand gas productions. • The changes in the H2 and CO2 emissions were compared. [ABSTRACT FROM AUTHOR]

Fabricating bamboo fiber‐reinforced epoxy composites (BFREs) using the vacuum‐assisted resin transfer molding (VARTM) process has many advantages, such as low cost, high product quality, controllability, and broad applicability. However, the immature fabrication process seriously affects product performance and hinders the full exploitation of the advantages of the VARTM process. The effects on the physical‐mechanical and thermal properties of BFREs by molding sequence and fiber content were investigated in this study. The molding sequence of fiber compression followed by resin injection was beneficial to ensure hermeticity, thus reducing the voids in the BFREs. The mechanical properties of BFREs gradually increased with increasing fiber content. With 50 wt% fiber content, the bending strength and modulus, shear strength, and impact toughness of BFREs reached 71.27 MPa, 6.78 GPa, 11.68 MPa, and 5.45 kJ/m2, respectively. Although the thermal stability of the BFREs was slightly lower than that of pure epoxy, the bamboo fibers' high rigidity evidentially increased the epoxy's dynamic mechanical properties. The life cycle assessment indicated that the BFREs effectively reduced the environmental impacts and production energy consumption compared to the glass fiber correspondent. The VARTM‐fabricated BFREs have great potential for construction, transportation, household items, packaging, sports equipment, and leisure goods applications. Highlights: Fiber compression followed by resin injection could ensure great hermeticity.Micro‐CT accurately measured the void characteristics of the composites.Voids had detrimental effects on the properties of the composites.Dense bamboo fiber preforms enhanced the mechanical properties of epoxy.Bamboo fibers reinforcing epoxy reduced the impact on the environment. [ABSTRACT FROM AUTHOR]

The combination of continuous natural fiber and fused filament fabrication (FFF) 3D printing enables the manufacturing of low carbon emitting, environment friendly, lightweight, and high strength biomass composites with designated geometry characteristics. In current literature, reviews associated with continuous fiber 3D printing primarily cover synthetic fibers, such as carbon fiber, Kevlar, and glass fiber. Very few pieces of literature on the FFF printing of continuous natural fibers are available. Techniques/methodologies for incorporating continuous natural fiber reinforcements in FFF is an emerging field of research. A comprehensive review and discussion on current progress and the future prospects of continuous natural fiber 3D printing would be beneficial to its development. This article summarizes the current research status of continuous natural fiber 3D printing, including information on printing techniques, materials, and the influence of printing parameters on composite properties, so as to provide reference for the future development of FFF technology using continuous natural fiber and thermoplastic composites. [ABSTRACT FROM AUTHOR]

A water and organic soluble N-benzyl-N,N-diethyl quaternized chitosan (NSQC) material was synthesized using chitosan, benzaldehyde, and bromoethane. Amino groups on chitosan reacted with benzaldehyde to form a Schiff base intermediate. Quaternized chitosan was obtained by reacting the Schiff base with bromoethane. The quaternized chitosan was dissolved in an organic solution with dissolved cellulose and cast to prepare quaternized chitosan/cellulose (QCC) film. The molecular structure, morphology, tensile strength, thermal stability, and antibacterial activity effects of NSQC-treated cellulose film were studied in detail. The results showed that the NSQC product exhibited superior solubility in deionized water and dimethylacetamide. The addition of NSQC as a reinforcing agent in QCC film enhanced the interlinking of fibers and slowed down the rate of cellulose pyrolysis, which improved the tensile properties and thermal stability of the cellulose film. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values of NSQC showed that it had good antibacterial activity against Staphylococcus aureus and Escherichia coli. The QCC film also showed contact sterilization ability with regards to two kinds of bacteria, which suggested that QCC film has the potential for applications in food packaging and bacterial barriers. [ABSTRACT FROM AUTHOR]

Highlights • Magnetron sputtering Cu film onto surface of self-bonded natural fiber product. • Rougher fibers surface achieved by chemical etching treatment before sputtering. • High hydrophobic performance obtained with a water contact angle of 131.5°. • High electromagnetic shielding effectiveness of 24.6 dB with thickness of 0.8 mm. Abstract To obtain the natural fiber products with high electromagnetic interference (EMI) shielding effectiveness (SE), magnetron sputtering Cu film was firstly applied to the surface of an eco-friendly self-bonded natural fiber product (SNFP) (0.8 mm in thickness). For a better combination of Cu film onto the SNFP surface, the chemical etching using sodium chlorite was newly used to treat the SNFP for obtaining an improved surface roughness. The surface morphology and chemical compositions were studied by the scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), and X-ray photoelectron spectroscopy (XPS). A rougher fiber surface was successfully obtained due to the shedding of surface lignin with decreased lignin content from 62% to 52% after the etching treatment. When sputtering Cu film for 1 h, 2 h, 3 h, and 4 h, the EMI SE values were increased to be 22 dB, 22.7 dB, 24.6 dB, and 25.5 dB, respectively, which all indicated that more than 99.4% incident signals were blocked. SEM observations revealed that an increased surface roughness could be achieved with the sputtering time increased from 1 h to 3 h. The water contact angle increased from 76.4° to 105.9° for 1 h sputtering, indicating that the sputtering Cu film could obviously improve the hydrophobic property of SNFP. When the sputtering time increased to be 3 h, this product exhibited the best hydrophobic performance with a maximum water contact angle of 131.5°. [ABSTRACT FROM AUTHOR]

Abstract To investigate the effect of manufacturing method on thermal and flammable performance of CaCO 3 impregnation modification (IM) treated bamboo pulp fiber (BPF) composites. The composite was made from HDPE with BPF contents of 30 wt% and 50 wt% by hot press molding (HPMP), extrusion molding (EMP) and injection molding process (IMP). The results showed that the E′ , crystallinity index (CrI) and heat distortion temperature (HDT) of the composites manufactured by EMP were highest. IM had a slight positive effect on E' and CrI of BPF/HDPE composites. The HDT of composites increased when the fiber content increased, leading to an increase in the heatproof property correspondingly. Compared to the samples manufactured by HPMP and EMP, the samples manufactured by IMP were extremely ignitable and flammable. Nano CaCO 3 could improve the flame retardancy performance of samples manufactured by EMP effectively and the fiber content had an effect on the flame retardancy performance of samples, especially the samples treated by nano CaCO 3. The average mass loss rate demonstrated a similar trend to the peak heat release rate for all composites. IM was more effective for EMP to improve the thermal stability and flame retardancy of composites compared with HPMP and IMP. Highlights • The composites were manufactured successfully by HPMP, EMP and IMP. • The E′ , CrI and HDT of the samples manufactured by EMP were highest. • The CrI of IM-BPF/HDPE composite was higher than that of BPF/HDPE composites. • The samples manufactured by IMP were extremely ignitable and flammable. • IM and fiber content had a different effect on composites manufactured by HPMP, EMP and IMP. [ABSTRACT FROM AUTHOR]

This research presents a novel and environmentally friendly approach for the synthesis of multifunctional nanobiocomposites for the efficient removal of toxic heavy metal and dye, as well as the disinfection of wastewater microorganisms. The nanobiocomposites (KAC-CS-AgNPs) were prepared by incorporating photochemically generated silver nanoparticles (AgNPs) within a chitosan (CS)-modified, high-surface-area activated carbon derived from kenaf (KAC), using a unique self-activation method. The even distribution of AgNPs was visible in the scanning electron microscopy images and a Fourier transform infra red study demonstrated major absorption peaks. The experimental results revealed that KA-CS-AgNPs exhibited exceptional adsorption efficiency for copper (Cu2+), lead (Pb2+), and Congo Red dye (CR), and showed potent antibacterial activity against Staphylococcus aureus and Escherichia coli. The maximum adsorption capacity (mg g−1) of KAC-CS-AgNPs was 71.5 for Cu2+, 72.3 for Pb2+, and 75.9 for CR, and the adsorption phenomena followed on the Freundlich and Langmuir isotherm models and the second-order kinetic model (R2 > 0.99). KAC-CS-AgNPs also exhibited excellent reusability of up to four consecutive cycles with minor losses in adsorption ability. The thermodynamic parameters indicated that the adsorption process was spontaneous and endothermic in nature. The bacterial inactivation tests demonstrated that KAC-CS-AgNPs had a strong bactericidal effect on both E. coli and S. aureus, with MIC calculated for E. coli and S. aureus as 32 µg mL−1 and 44 µg mL−1, respectively. The synthesized bioinspired nanocomposite KAC-CS-AgNPs could be an innovative solution for effective and sustainable wastewater treatment and has great potential for commercial applications. [ABSTRACT FROM AUTHOR]

The behavior of pressed poplar chemi-thermomechanical pulping (CTMP) without additive the focus of our study. Four CTMPs with decreasing lignin contents were prepared by the sodium chlorite/acetic acid method and the holocellulose, α-cellulose, pentosan and Klason lignin contents of the delignified CTMPs were determined. The surface composition, aggregation structure and microstructure of the delignified fibers were characterized by X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and scanning electron microscope (SEM), and the mechanical properties of the fiber material were investigated by means of tensile and bending tests. As shown by XPS, the lignin content of the Pr-CTMP surface layer firstly increased and then decreased as the lignin content of CTMP decreased. With the delignification time increased from 0 to 240 min, the crystallinity index (CrI) of CTMP increased from 60.1% to 65.7%. The CrI of all CTMPs at different delignification degrees showed significant elevated values after hot-pressing. The fiber cell wall became thinner and the cells were flattened and thus elevated the contact area among fibers and, as a consequence, the density of material gradually increased at higher delignification degrees. The tensile strength increased by ca. 10%, when the lignin content decreased from 24.9% to 13.1%, and by ca. 53%, when the lignin content decreased from 13.1% to nearly zero. The bending strength increased with increasing delignification. When the removal rate of lignin increased from 47% to 54%, the bending strength increased from 101 to 122 MPa. [ABSTRACT FROM AUTHOR]

The behaviors of the mechanical, hydrophobic, and thermal properties of the molded fiber product (MFP) were examined after the removal of residual lignin. The fibers resulting from the chemi-thermomechanical pulping and bleaching processes were treated by extended delignification, namely by their reaction with glacial acetic acid and sodium chlorite. The changes in surface composition, chemical structure, crystallinity, microstructure, and thermal stability of the MFP were investigated by X-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), and thermogravimetric analysis (TGA), respectively. Results showed that the composition and structure of carbohydrates on the fiber surface were not changed significantly, the lignin in fibers was almost completely removed, the relative content of intermolecular hydrogen bonds in cellulose and the contact area between fibers was increased, and the crystallinity index increased from 79.5% to 81.4% after the extended delignification. When the content of lignin decreased from 5.78% to 0.02%, the tensile strength of the MFP increased 25.6%, but little changes were found in the bending strength. The onset thermal decomposition temperature of MFP increased from 242 °C to 250 °C and the maximum rate of degradation temperature increased from 347 °C to 350 °C. [ABSTRACT FROM AUTHOR]

The potential utility of seawater desalination technologies (such as thermal distillation, membrane desalination, and solar steam generation) has been recognized with the growing shortage of freshwater resources. A better knowledge of such techniques thus needs to be built to efficiently achieve freshwater production. This paper reviews the desalination technologies with respect to the working principle, environmental risks, merits/demerits, and economic benefits. Our discussion has been extended further to propose the strategies needed to overcome the shortcomings of the major solar desalination technologies at the present. An outlook on the future direction of this research field is also presented. This paper is thus expected to set the valuable reference for the production of freshwater based on the desalination techniques. [Display omitted] • The merits/disadvantages of different desalination technologies are evaluated. • The salt barrier mitigation methods for various solar steam generation are highlighted. • Optimal desalination technologies under different conditions are discussed. • Economic analysis and environmental assessment of desalination are carried out. • The challenges and future direction of seawater desalination studies are addressed. [ABSTRACT FROM AUTHOR]

Using natural fiber mats, aluminum sheets and epoxy resin, hybrid composites were fabricated through vacuum assisted resin transfer molding (VARTM) process. With novel sandwich structures, these hybrid composites contain natural fiber-based shells and ultra-thin aluminum sheet core. The hybrid composites offered excellent electromagnetic interference (EMI) shielding performance with good mechanical properties inherited from aluminum sheets and natural fiber-based composites, respectively. Furthermore, the shell material (natural fiber-based composites) provides protection of the aluminum sheets from exposing to atmosphere directly to prevent being corroded. In this study, the EMI shielding effectiveness, microstructure, flexure property, tensile property, and internal bonding strength of the hybrid composites were examined. The excellent EMI shielding performance and good mechanical properties enable the new hybrid composites to be used as engineering materials in the EMI protection fields. [ABSTRACT FROM AUTHOR]

The cadmium-contaminated water body is a worldwide concern for the environment and toxic to human beings and the removal of cadmium ions from drinking and groundwater sustainably and cost-effectively is important. A novel nano-biocomposite was obtained by impregnating silver nanoparticles (AgNPs) within kenaf-based activated carbon (KAC) in the presence of chitosan matrix (CS) by a simple, facile photoirradiation method. The nano-biocomposite (CS-KAC-Ag) was characterized by an environmental scanning electron microscope equipped with energy dispersive X-ray spectroscopy (ESEM-EDX), Fourier-transform infrared spectroscopy (FTIR), and Brunauer–Emmett–Teller (BET) method. A Box–Behnken design of response surface methodology (RSM) was used to optimize the adsorption of Cd2+. It was found that 95.1% of Cd2+ (10 mg L−1) was eliminated at pH 9, contact time of 120 min, and adsorbent dosage of 20 mg, respectively. The adsorption of Cd2+ by CS-KAC-Ag is also in agreement with the pseudo-second-order kinetic model with an R2 (coefficient of determination) factor greater than 99%. The lab data were also corroborated by tests conducted using water samples collected from mining sites in Mexico. Along with Cd2+, the CS-KAC-Ag exhibited superior removal efficiency towards Cr6+ (91.7%) > Ni2+ (84.4%) > Co2+ (80.5%) at pH 6.5 and 0.2 g L−1 dose of the nano-adsorbent. Moreover, the adsorbent was regenerated, and the adsorption capacity remained unaltered after five successive cycles. The results showed that synthesized CS-KAC-Ag was a biocompatible and versatile porous filtering material for the decontamination of different toxic metal ions. [ABSTRACT FROM AUTHOR]

To study the feasibility and applicability of air energy assisted solar drying under low radiation value conditions in sub frigid zone regions, an intermittent air energy assisted solar heating (IAEASH) process was developed using the 100 Degrees Celsius Test Method and the controlled variable method. Experiments were conducted on two drying processes, namely, continuous air energy assisted solar heating (CAEASH) and IAEASH, using an air energy assisted solar drying system. Poplar sawn lumbers were used in the experiments. The drying processes of both CAEASH and IAEASH methods were compared and analyzed. Results showed that the effective heating time for IAEASH was reduced by 21 h compared to CAEASH, with an average of 23.9%/h increase in drying rate during effective heating. The average radial and tangential dry shrinkage strains of IAEASH during drying ranged from −0.011 to 0.048 and from 0.004 to 0.039 respectively, which were better than the experimental results of CAEASH, and reduced the shrinking of poplar lumber. The IAEASH dried lumber showed neater arrangement between cells. The power consumption of IAEASH was 314.5 kWh, which represented a 50.7% improvement in energy efficiency compared to CAEASH. In summary, the developed IAEASH process is feasible for application in sub frigid zone regions. [ABSTRACT FROM AUTHOR]

Design of eco-friendly, non-formaldehyde and flame retardant wood adhesives is in high demand for the wood industry, which can help to alleviate environmental stress and human health concerns. Magnesium oxychloride cement (MOC) can reduce CO 2 emission and increase the value-added utilization of potash industry wastes, making it an ideal alternative to hazardous formaldehyde-based adhesives. However, its practical application usually suffers from poor water resistance and the filtering effect of wood. Inspired by the porous structure of cuttlebone, a facile yet powerful strategy is presented to prepare MOC adhesive with outstanding water resistance, compressive strength and adhesive ability to wood through introducing biochar. The naturally porous structure of biochar can form a protective core-shell structure and encapsulation with hydration products to stabilize phase 5 (5Mg(OH) 2 ·MgCl 2 ·8H 2 O), avoid crack extension and mitigate the filtering effect of wood. Meanwhile, the abundant functional groups of biochar can construct multiple interactions with Mg2+, which contributes to forming an internal network with excellent cohesion strength. Compared with pristine MOC, the obtained MOC/Biochar exhibited 102.33%, 32.33% and 31.45% increases in water resistance, compressive strength and wet adhesion strength, respectively. This work provides a promising strategy in preparing eco-friendly MOC-based adhesive from agricultural and industrial by-products to reduce environmental hazards. [Display omitted] • An eco-friendly, flame retardant and non-formaldehyde wood adhesive was proposed. • Biochar was used to form multiple interactions in magnesium oxychloride cement. • The composite showed integrated water resistance and compressive strength. • Adhesive alleviated the filtering effect of wood and showed good adhesion strength. [ABSTRACT FROM AUTHOR]

Exploring the reusability of wood-based panels is imperative in the wood industry for sustainable development and carbon balance. Non-reusable adhesives make wood-based panel recycling difficult. In this study, inspired by the adhesion and de-adhesion behavior of snail slime, we built dynamic covalent/hydrogen hybrid networks into adhesive system for achieving both high bonding performance and reusability. Specifically, the softwood lignin was purified and pretreated by ultrasonication to form a catechol structure (UAL) and then combined with soybean protein to develop a 100 % bio-based wood adhesive. The catechol structure of UAL formed dynamic covalent bonds (C N) with the amino groups of the protein to improve the water resistance and formed multiple hydrogen bonds as a sacrificial network to improve the toughness of the adhesive. Thus, the wet shear strength of plywood bonded by the resultant adhesive improved by 101.4 % to 1.37 MPa. The adhesive also exhibited flame retardancy (LOI = 37.7 %), mildew resistance (60 h), and antibacterial performance (inhibition zone = 8 mm). Notably, owing to the rearrangement of dynamic covalent/hydrogen hybrid networks and the thermoplastic property of UAL, the resultant adhesive was reusable (3 cycles) and degradable (2 months), which provides a potential method for the reuse of wood-based panels. • Ultrasonic treats lignin to form catechol structure (UAL) and combine with SPI to obtain adhesive. • Dynamic covalent/hydrogen hybrid networks were constructed in adhesive system. • The SPI/UAL adhesive has good coating, prepressing intension, and bonding performance. • The SPI/UAL adhesive exhibited good antibacterial, flame-retardant, and mildew resistance. • The resultant wood-based panel was reusable and biodegradable. [ABSTRACT FROM AUTHOR]

Woodceramics were fabricated in a vacuum through carbonization of wood powder impregnated with phenol formaldehyde (PF) resin. The effects of carbonization temperature and mass ratio of wood/resin on electromagnetic interference (EMI) shielding effectiveness (SE) and morphology of woodceramics were explored. The PF resin made wood cell walls have the characteristics of glassy carbon. Wood axial tracheid and ray cells were filled with more glassy carbon by increasing addition of PF resin. Moreover, the increase of carbonization temperature was beneficial to improving SE. Woodceramics (mass ratio 1:1) obtained at 1000 °C presented a medium SE level between 30 MHz and 1.5 GHz. [ABSTRACT FROM AUTHOR]

To fabricate kenaf fiber composites with electromagnetic interference (EMI) shielding function, the technique of vacuum-assisted resin transfer molding (VARTM) and Cu film magnetron sputtering were employed. The EMI shielding effectiveness (SE) and composite surface characteristics were examined with PNA Network Analyzer, Quanta 200 environmental scanning electron microscope and OCA20 contact angle meter. After being Cu-sputter coated for 0.5 h, 1 h, 2 h, and 3 h, the EMI SE values were increased to be 23.8 dB, 32.5 dB, 43.3 dB, and 48.3 dB, which denoted 99.5799%, 99.9437%, 99.9953%, or 99.9985% incident signal was blocked, respectively. The SEM observations revealed that the smoother surface of the composites was obtained by longer time sputtering, resulting in the SE improvement. The contact angle increased from 49.6° to 129.5° after 0.5 h sputtering, which indicated that the coated Cu film dramatically improved the hydrophobic property of composite. When the coating time increased to 3 h, the contact angle decreased to 51.0° because the composite surface roughness decreased with the increase in coating time. [ABSTRACT FROM AUTHOR]

To enhance the mechanical and water-resistant properties of soy protein isolate (SPI) based films, hydrophobic TriSilanolPhenyl polyhedral oligomeric silsesquioxanes (POSS) was incorporated to modify the SPI films. POSS has three SiOH groups in a molecular, which is employed to cross-link SPI with the help of 3-glycidoxypropyltrimethoxysilane (GPTMS). POSS is a structure of eight phenol groups, playing a critical role in improving the physical and mechanical properties. The X-ray diffraction (XRD) and attenuated total reflectance (ATR) Fourier transform infrared spectroscopy (FT-IR) were used to characterize the films. The degree of reaction of SiOH groups in the POSS was estimated to be 53.0% according with the absorbance of ATR FT-IR spectra. Although the elongation at break was reduced by 52.6%, the tensile modulus, tensile strength and 10% offset yield strength were significantly increased by 86.6%, 34.0% and 56.8%, respectively, due to the cross-linking reactions among SPI, GPTMS and POSS. The results of water-resistant tests showed that the 24-hour water absorption was dramatically reduced by 54.7%. [ABSTRACT FROM AUTHOR]

This work was to apply the vacuum-assisted resin transfer molding (VARTM) process and use aluminum hydroxide inorganic nanoparticle impregnation (INI) to improve the mechanical properties and water resistance of the kenaf fiber reinforced composites. As a novel technique, a two-step aluminum hydroxide impregnation was used in the fabrication of composites, including the alkali retting and aluminum hydroxide loading. After the alkali retting, the cellulose content of the kenaf fibers went up to 94.2%, the ash content was 2.7%. The tensile strength and modulus of individual fiber were 810 MPa and 13.5 GPa, respectively. The results showed that, with a loading amount of 2.2% aluminum hydroxide, the modulus of elasticity, modulus of rupture, tensile modulus and tensile strength of the composites made with INI-treated fibers were increased by 67.2%, 55.7%, 32.5% and 36.3%, respectively, compared with those of composites made from un-treated fibers. When the INI-treated fibers were employed, the thickness swelling of 24-h water submersion was reduced from 19.7 to 6.3%, and the moisture contents of the composites after the conditioning and water submersion were reduced from 5.8% to 1.9%, and 18.3% to 6.6%, respectively. The improvement makes the kenaf fiber reinforced composites possible to replace the glass fiber composites for the automotive application. [ABSTRACT FROM AUTHOR]

This study proposed a novel multiscale prediction strategy, including mesoscale and macroscale damage evolution modeling, to investigate the effective properties and progressive damage failure behavior of plain-woven reinforced composites (PWRCs) under various external loads (tension, compression). A high-precision mesoscale representative volume element (RVE) that could accurately describe the local mechanical behavior of PWRCs was developed by combining experimental characterization (scanning electron microscope and X-ray computed tomography) and numerical simulation. To solve the problem of inaccurate prediction results caused by multiscale characteristics and complex stress changes in the damaged area of PWRCs, the strain-based 3D Hashin failure criterion and the multiscale damage models were used to predict the damage initiation and evolution of mesoscale reinforcement (bamboo fiber yarn bundle) and macroscale composites, respectively. Considering the damage evolution law of isotropic materials, a damage model based on the Von Mises criterion was used to characterize the damage initiation and evolution of mesoscale matrix epoxy resin (EP) under external loading. The effective properties and mechanical behavior of the PWRCs were transferred from mesoscale to macroscale through the progressive homogenization method. The bilinear constitutive relationship of the mixed-mode cohesive element was used to characterize the interlaminar failure of the PWRCs. Finally, the corresponding mechanical characterization (tension, compression) of the PWRCs was carried out. Moreover, the experimental results were highly consistent with the simulation results, verifying the reliability of the novel multiscale prediction strategy in investigating the mechanical response of the PWRCs at multiple scales and revealing the damage mechanism of the PWRCs. [Display omitted] • A novel strategy can precisely predict the multiscale mechanical response of natural fiber-reinforced composites. • A high-precision mesoscale model is used to capture the local mechanical behavior of plain-woven reinforced composites. • Strain-based failure criterion and multiscale damage models can accurately predict the progressive damage behavior. • The dynamic coupling of mesoscale and macroscale accurately predicts the macroscale mechanical behavior. [ABSTRACT FROM AUTHOR]

The development of a biomass adhesive as a substitute for petroleum-derived adhesives has been considered a viable option. However, achieving both superior bonding strength and toughness in biomass adhesives remains a significant challenge. Inspired by the human skeletal muscles structure, this study reveals a promising supramolecular structure using tannin acid (TA) functionalized poly-β-cyclodextrin (PCD) (TA@PCD) as elastic tissues and chitin nanocrystals (ChNCs) as green reinforcements to strengthen the soybean meal (SM) adhesive crosslinking network. TA@PCD acts as a dynamic crosslinker that facilitates reversible host-guest interactions, hydrogen bonds, and electrostatic interactions between adjacent stiff ChNCs and SM matrix, resulting in satisfactory strength and toughness. The resulting SM/TA@PCD/ChNCs-2 adhesive has demonstrated satisfactory wet and dry shear strength (1.25 MPa and 2.57 MPa, respectively), toughness (0.69 J), and long-term solvents resistance (80 d). Furthermore, the adhesive can exhibit desirable antimildew characteristics owing to the phenol hydroxyl groups of TA and amino groups of ChNCs. This work showcases an effective supramolecular chemistry strategy for fabricating high-performance biomass adhesives with great potential for practical applications. [Display omitted] [ABSTRACT FROM AUTHOR]

Human health and environmental protection demand wood-based panel industry for innovative soy-based adhesives with high production efficiency, straightforward synthesis processes, non-toxicity, and high bonding performance. A simple and efficient microwave pretreatment process and low addition of bio-derived crosslinking agent was used in this study to prepare a non-toxic and high-bonding performance soybean protein-based adhesive. After 4 min of microwave pretreatment time, the complex quaternary structure of soybean protein molecule unfolds, the soybean protein disperses evenly and stably, and active groups of soybean protein molecules are exposed. After adding 3.85% crosslinking agent, the moisture absorption rate of the soybean protein-based adhesive decreases by 41.77%, the residual rate increases by 3.68%, and the wet shear strength of the resultant plywood increases to 1.12 MPa, which satisfies requirement of interior use plywood. Compared with previously reported soy-based adhesives, this adhesive is dependent on fewer chemical reagents, but has good bonding performance. The 204.41% of relative cell viability indicates the resultant adhesive was non-toxic. The proposed high-efficiency, high-performance, non-toxic biomass adhesive has great prospects for the industrial application. • A non-toxic and high-performance soybean protein-based adhesive was developed. • Microwave treatment (MT) breaks soybean protein molecule and exposes active groups. • After 4 mins MT, the wet shear strength of resultant plywood increased by 160.47%. • MT reduces the dosage of chemical reagent for soybean protein-based adhesive. • Relative cell viability of modified soybean protein-based adhesive reaches 204.41%. [ABSTRACT FROM AUTHOR]

The drying process of waterborne wood coating (WWC) is mainly driven by the moisture gradient, part of the water evaporates to the air, other part enters into the wood structure. The water absorption and conduction rate vary within various wood substrates, which have a great influence on the drying rate of WWC. Herein, the focus of this paper is on studying the influence of water movement behavior on the drying efficiency and film-forming performance of WWC under conventional hot-air drying process. A waterborne acrylic-polyurethane was used as representative coating in the study. It was found that balsa wood had more pores and higher specific surface area than oak wood, allowing a faster water transfer at the wood surface. The shortest surface and hard drying time of 573 s and 1393 s were achieved at 60 °C and 40% relative humidity for WWC on balsa wood. The dynamic drying rate study showed that the water transfer on the surface of oak was slower than that of balsa. Based on the film-forming performance of WWC under different drying conditions, a better film property could be obtained by adjusting the drying conditions to achieve a dynamic balance between water evaporation to air and water transfer into the wood substrate. The drying characteristics of WWC on different wood surfaces and drying conditions were comprehensively evaluated by radar map analysis. The results in this work contributed to the efficient and green processing in furniture and coating industries. [ABSTRACT FROM AUTHOR]

The objective of this study was to investigate the optimum processing parameters to manufacture wood-bamboo hybrid composites for railway sleepers. Wood particles and bamboo strips were used as reinforcing materials, and phenol formaldehyde resin was used as matrix. About 108 composite boards with resin contents of 8% to 15.5%, target densities of 0.55 to 1.05 g/cm3, hot-pressing time of 0.40 to 0.65 min/mm, and press temperatures of 165℃ to 175℃ were fabricated. The effect of manufacturing parameters on the properties of the sleepers was examined. Regression equations were developed to illustrate the relationships between processing parameters and the sleeper properties, i.e. modulus of rapture (MOR), modulus of elasticity (MOE), internal bonding (IB), and thickness swelling (TS). A nonlinear programming model was derived, from which the composite sleeper properties can be estimated. Given the manufacturing conditions (resin content, target composite density, press time, and press temperature), the composite sleeper properties can be estimated. Using the nonlinear programming model, the optimal MOR, MOE, IB, or TS could be obtained under certain practical constraints. When a resin content of 15.5%, target density of 0.8 g/cm3, hot-pressing time of 0.65 min/mm, and hot-pressing temperature of 170℃ were used, the optimal MOR value of 70.08 MPa was obtained under the conditions that MOE, IB, and TS be greater than the requirements of the standards. [ABSTRACT FROM PUBLISHER]

Kenaf fiber-filled polyurethane foams were prepared using the free rising method. The dielectric constants and the loss tangents of the composites were studied as functions of fiber content (0, 5, 10, and 15 parts per hundred of polyols by weight), temperature (from 30 to 200 °C), and electric field frequency (from 20 Hz to 2 MHz). The dielectric constant and the loss tangent increased with increasing fiber content. The dielectric constant was very high in the range of 10¹ to 10² Hz and varied little in the range of 10³ to 106 Hz, but decreased rapidly above 106 Hz. The loss tangent decreased as the frequency increased. The effect of frequency on the loss tangent value was greater at frequencies below 10² Hz. Higher temperatures led to a higher dielectric constant and loss tangent. When the temperature was above approximately 120 °C, the loss tangent dramatically increased. The incorporation of kenaf fiber can improve the growth rate of the dielectric constant with increasing temperature. The dielectric constant and the loss tangent increased with increasing fiber content, indicating that both the dielectric capability and energy dissipation ability of the composites were improved. [ABSTRACT FROM AUTHOR]

Cellulose nano-whiskers were used to enhance the performance of soybean meal-based adhesive. Soybean meal flour, cellulose nano-whiskers (CNW), sodium hydroxide (NaOH), and polyethylene glycol (PEG) were used to develop different adhesive formulations. The effect of adhesive components on water resistance of the adhesive was measured on the three-ply plywood (three cycle soak test). The viscosity and solid content of the adhesive were measured. The cross section of the cured adhesives was evaluated using scanning electron microscopy (SEM). The effect of the hot press parameters on the water resistance of the plywood bonded by soybean meal/CNW/NaOH/PEG adhesive was investigated. The results showed that using the CNW in the adhesive formulation improved the water resistance of the plywood by 20%. The plywood bonded by the soybean meal/CNW/NaOH/PEG adhesive met the interior plywood requirement (2000 (ANSI/HPVA HP-1)). Fewer holes and cracks, as well as a smooth surface were observed on the cross section of the cured adhesive after the incorporation of CNW. In the hot press process, the water resistance of the plywood bonded by the soybean meal/CNW/NaOH/PEG adhesive increased as the hot press temperature and time increased. [ABSTRACT FROM AUTHOR]

• Simultaneously flame retarded, high bonding strength and formaldehyde-free adhesive was fabricated. • A stable system of organic–inorganic hybridization was constructed. • The wet shear bond strength of lap plate increased by 53.5%. • Inorganic adhesive greatly reduced total heat release and total smoke production rate of wood-based composites. Developing high performance and non-toxic adhesives to replace the petroleum-based adhesives are highly desirable for wood industry. The use of magnesium oxychloride cement (MOC) inorganic adhesive is beneficial for the protection of human health and conservation of fossil resources. However, the low initial viscosity and poor water resistance have limited their application in plywood fabrication. In this study, polyacrylamide (PAM) and sodium polyacrylate (PAAS) were added to the adhesive as organic agents to construct wood-based composites by the organic–inorganic hybrid strategy. The MOC would be solidified by a cold-pressing method, forming a formaldehyde-free wood adhesive with high bonding performance. The addition of PAM efficiently improved the stability and processability of MOC, while PAAS improved the water resistance of MOC by inducing Mg2+ chelation and transforming the phase 5 structure. This adhesive exhibited a 53.5% increase in wet shear strength in contrast with the unmodified MOC adhesive. In addition, the MOC adhesive bonded wood-based composites showed high flame-retardant properties. [ABSTRACT FROM AUTHOR]

Wood is a sustainable structural material, but it cannot be easily shaped while maintaining its mechanical properties. We report a processing strategy that uses cell wall engineering to shape flat sheets of hardwood into versatile three-dimensional (3D) structures. After breaking down wood’s lignin component and closing the vessels and fibers by evaporating water, we partially re-swell the wood in a rapid water-shock process that selectively opens the vessels. This forms a distinct wrinkled cell wall structure that allows the material to be folded and molded into desired shapes. The resulting 3D-molded wood is six times stronger than the starting wood and comparable to widely used lightweight materials such as aluminum alloys. This approach widens wood’s potential as a structural material, with lower environmental impact for buildings and transportation applications. [ABSTRACT FROM AUTHOR]

Development of mechanical robust and functional biomass‐based materials still remains challenging. Here, a design strategy inspired by spider silk structure is proposed to prepare strong, robust, and photoluminescent soybean protein isolate (SPI)‐based materials, by integrating epoxy soybean oil (ESO) and SPI as soft phase matrices and graphene oxide quantum dots (GQDs) as hard phase. The results show that the soft–hard coordination network can form a close covalent/hydrogen bond network. The tensile strength, elongation at break, and toughness of the SPI/ESO/GQD film are 13.22 MPa, 209%, and 22.54 MJ m−3, respectively. In addition, SPI/ESO/GQD has strong photoluminescence intensity due to the ring‐opening polymerization of amino structure with epoxy resin. The prepared SPI‐based materials are promising candidates for optical coatings and provide new ideas for the intelligent research of other protein‐based materials. [ABSTRACT FROM AUTHOR]

Soy protein isolate (SPI) film is considered a promising biomaterial for the replacement of petroleum‐based food packaging plastics. However, current SPI films are still replying on petroleum‐based crosslink agents. In this paper, a green and effective approach is developed to prepare a full biomass‐based sustainable film with high strength and toughness by incorporating feather keratin (FK, extracted from the waste chicken feathers) into the SPI via the reaction of disulfide bonds. The broken disulfide bonds in FK are recombined with the sulfhydryl group on the SPI molecular chains to form a cross‐linked network. Compared to the SPI film, the tensile strength of the SPI/FK composite film is increased by 242% to 8.2 MPa and the toughness is increased by 152% to 9.18 MJ m−3. The thermal stability and the water resistance of the SPI/FK composite films are also improved. The replacement rate of FK‐modified SPI is up to 40%. Since the film is 100% made from bio‐based materials, it would be biodegradable. This research provides a green and economic approach to improve the performance of protein‐based food packaging films by introducing FK as an enhancer and constructing disulfide bonds cross‐linked network structure in the protein system. [ABSTRACT FROM AUTHOR]

Discontinuities due to weather conditions and daylight affect solar drying, so to address that, a working mechanism of air energy-assisted solar drying was developed in this study. An air-energy assisted solar dryer was used to dry timber, from a green average moisture content of 183%–11.3% in 161.5 h, where the moisture diffusion coefficient ranged from 1.28 ×10-10 m2/s to 6.41 ×10-9 m2/s. The effective solar radiation intensity during drying ranged from 221.3 to 750.3 W/m2. The overall drying efficiency was 30.7%, and the effective solar heat supply ratio was 58.5%. The specific moisture extraction rate and specific energy consumption were measured within a range of 0.32–3.0 kg/kWh and 924 - 11390 kJ/kg, respectively. The average power consumption per m3 of wood volume was 254.2 kW h/m3. The results showed that the energy-assisted solar dryer was suitable for a condition with low radiation and various weather conditions. • An air-energy-assisted solar dryer. • The wood solar drying process based on the moisture content schedule. • The thermodynamics and quality of wood dried in an AEASD are investigated. • The effective solar heating ratio of 58.5% and a drying efficiency of 30.7%. • The feasibility of AEASD under low radiation and variable weather conditions. [ABSTRACT FROM AUTHOR]

Developing multifunctional adhesives with exceptional cold-pressing strength, water resistance, toughness, and mildew resistance remains challenging. Herein, inspired by oysters, a multifunctional organic-inorganic hybrid soybean meal (SM)-based adhesive was fabricated by incorporating amino-modified carbon dots functionalized silica nanoparticles (CDs@SiO 2) and dialdehyde chitosan (DCS) into SM matrix. DCS effectively enhanced the interface interactions of organic-inorganic phases and the rigid nanofillers CDs@SiO 2 uniformly dispersed in the SM matrix, which provided energy dissipation to improve the adhesive's toughness. Owing to the stiff skeleton structure and enhanced crosslinking density, the crosslinker-modified SM (MSM)/DCS/CDs@SiO 2 –2 wood adhesive exhibited outstanding cold-pressing strength (0.74 MPa), wet shear strength (1.36 MPa), and long-term water resistance (49 d). Additionally, the resultant adhesive showed superior antimildew and antibacterial properties benefiting from the introduction of DCS. Intriguingly, the fluorescent properties endowed by carbon dots further broadened the application of adhesives for realizing security testing. This study opens a new pathway for the synthesis of multifunctional biomass adhesives in industrial and household applications. [Display omitted] [ABSTRACT FROM AUTHOR]