Configuring single-layer MXene nanosheet onto natural wood fiber via C-Ti-C covalent bonds for high-stability Li-S batteries

Lithium-sulfur batteries(LSBs)are considered promising candidates for next-generation battery technologies owing to their outstanding theoretical energy density and cost-effectiveness.However,the low conductivity and polysulfide shuttling effect of S cathodes severely hamper the practical performance of LSBs.Herein,in situ-generated single layer MXene nanosheet/hierarchical porous carbonized wood fiber(MX/PCWF)composites are prepared via a nonhazardous eutectic activation strategy coupled with pyrolysis-induced gas diffusion.The unique architecture,wherein single layer MXene nanosheets are constructed on carbonized wood fiber walls,ensures rapid polysulfide conversion and continuous electron transfer for redox reactions.The C-Ti-C bonds formed between MXene and PCWF can considerably expedite the conversion of polysulfides,effectively suppressing the shuttle effect.An impressive capacity of 1301.1 m A h g^(-1)at 0.5 C accompanied by remarkable stability is attained with the MX/PCWF host,as evidenced by the capacity maintenance of 722.6 m A h g^(-1)after 500 cycles.Notably,the MX/PCWF/S cathode can still deliver a high capacity of 886.8 m A h g^(-1)at a high S loading of 5.6 mg cm^(-2).The construction of two-dimensional MXenes on natural wood fiber walls offers a competitive edge over S-based cathode materials and demonstrates a novel strategy for developing high-performance batteries.

Rheological and mechanical properties of wood fiber-PP/PE blend composites

For evaluation of the rheological and mechanical properties of highly filled wood plastic composites （WPCs）, polypropylene/polyethylene （PP/PE） blends were grafted with maleic anhydride （MAH） to enhance the interfacial adhesion between wood fiber and matrix. WPCs were prepared from wood fiber up to 60 wt.% and modified PP/PE was blended by extrusion. The rheological properties were studied by using dynamic measurement. According to the strain sweep test, the linear viscoelastic region of composites in the melt was determined. The result showed that the storage modulus was independent of the strain at low strain region （〈0.1%）. The frequency sweep resuits indicated that all composites exhibited shear thinning behavior, and both the storage modulus and complex viscosity of MAH modified composites were decreased comparing to those unmodified. Flexural properties and impact strength of the prepared WPCs were measured according to the relevant standard specifications. The flexural and impact strength of the manufactured composites significantly increased and reached a maximum when MAH dosage was 1.0 wt%, whereas the flexural modulus after an initial decreased, also increased with MAH dosage. The increase in mechanical properties indicated that the presence of anhydride groups enhanced the interracial adhesion between wood fiber and PP/PE blends.

Properties of paper mill sludge–wood fiber–HDPE composites after exposure to xenon-arc weathering

We used paper mill sludge（PMS） to substitute for part of the wood fibers（WF） used to reinforce high density polyethylene（HDPE）.The resulting composites were subjected to xenon-arc weathering.The composite filled with limited PMS（under 10 %） had mechanical properties and aging resistance similar to those without PMS.The composites containing more PMS faded and cracked more readily than those without PMS.Based on the carbonyl index,crystallinity,and wood index,PMS appeared to accelerate the degradation of composites during weathering.Adding PMS to WF–HDPE composites reduced the weathering resistance,and this reduction was not significant if the PMS content did not exceed 20 % of the wood fibers.Therefore,PMS could be used as a reinforcement in wood-plastic composites at levels less than20 % of the wood fiber content.

The Accelerated Thermo-Oxidative Aging Characteristics of Wood Fiber/Polycaprolactone Composite:Effect of Temperature,Humidity and Time

This study investigated the characteristics of wood fiber/polycaprolactone composite after an artificial accelerated thermo-oxidative aging treatment.The effect of time,temperature and humidity during the treatment on their mechanical,chemical and morphology properties were evaluated.The composite was prepared from melted wood fibers and modified polycaprolactone by a molding process.A temperature and humidity controllable test chamber was used for the thermo-oxidative aging of the composite.The thermo-oxidative aging caused surface of the composite to be much more rougher and even a few cracks and holes appeared on it.According to the spectra of Fourier Transform Infrared(FTIR)and Gel Permeation Chromatography(GPC),C=O in the molecular chain of polycaprolactone was hydrolyzed and C–O was broken after the aging treatment,which resulted in a reduction in average molecular weight of the composite.Moreover,results showed that the mechanical strength decreased a lot with the increase in time,temperature and humidity,and the effect of temperature and humidity was more significant compared with that of time.Controlling the temperature and humidity during thermo-oxidative aging treatment could accelerate the aging of composite,which provided a quick and effective method for evaluating the aging resistance of the composite.

Qualitative and Quantitative Characterization of Wood Fibers of Shrubs and Tree Species of the Tamaulipan Thorn Scrub, Northeastern Mexico and Its Possible Relation to Wood Quality and Utilization

The present study was undertaken to determine the variability in fiber cell morphology and its length among wood species of the Tamaulipan Thorn Scrub, Northeastern Mexico, used for various uses such as timber for furniture, fence, post, firewood and sources of forage. The results reveal large variability in fiber cell morphology and fiber cell dimensions. The species are classified on the basis of its fiber cell morphology and fiber cell length and recommended for their possible utilization for different purposes. Wood having fibre cells with broad lumen and thin wall could be suitable for the manufacture of paper documented in the literature viz. Acacia farnesciana, Caesalpinia mexicana, Cordia boisiieri, Diospyros palmeri, Forestieria angustifolia, Morus celtifolia, Prosopis laevigata. This technique can be used in preliminary screening of woody species for its utilization for different purposes. Further studies are needed to confirm.

Effect of maleic anhydride grafted styrene-ethylene-butylene-styrene （MA-SEBS） on impact fracture behavior of polypropylene / wood fiber composites

MA-SEBS as compatibilizer and impact modifier was incorporated into Polypropylene/Wood Fiber （PP/WF） to enhance interface adhesion and impact strength of the composite. The effect of MA-SEBS content on the impact fracture behavior of PP/WF composites was studied. The impact properties of composites with 8% MA-SEBS reached the maximum value. And further increasing of MA-SEBS content to 10% did not improve the fracture toughness, but improved the stiffness of composites by DMA analysis. This was attributed to the improved PP/WF adhesion. As the MA-SEBS content is more than 8%, the molecule interaction of PP and WF was expected to much stronger than lower MA-SEBS. Scanning electron microscopy （SEM） was performed to analyze the impact fracture surface and showed a stronger affinity for the wood surfaces.

Effect of Wood Variables on the Properties of Wood Fiber-Polypropylene Composites

The effect of wood species (Chinese fir and Poplar), wood fiber content (10%, 25%, 40%) and wood fiber sizes (16 to 32 mesh, 32-65 mesh, above 65 mesh) on the properties of the wood fiber-Polypropylene composites were studied in this paper. The results indicate that the effect of wood fiber content and size in composite were more important than that of chosen wood species. Compared with polypropylene without wood fiber, the flexural strength of the composites increased when adding wood fiber into polypr...

INVESTIGATION OF SOFTENING AGENT PREPARATION AND PERFORMANCE OF HANDMADE ECOCOMPOSITES WITH CONIFEROUS WOOD AND BASALT FIBERS

In this investigation, basalt mineral fiber softening agent was prepared in order to obtain desirable flexible performance. Stability and physical chemistry natures of softening agent were evaluated by particle size distribution, dilution, storage and folding endurance etc. Constitutes of basalt and wood fibers were determined by energy dispersion analysis X-ray which served as an accessory of scanning electron microscopy (SEM-EDAX). Naturally degradable ecocomposite was prepared by basalt and wood fibers. The results of SEM observation illustrated that the wood and basalt fibers were blended uniformly. The impact factors of beating degree, content of wood fibers and adhesive etc. were discussed. The structure of the naturally degradable ecocomposite was contrasted with that of pure wood fibers and the cause of excellent filtration performance was analyzed. Compared with traditional methods, it was of saving wood resource, a large amount of water and reducing second pollution. As a consequence, the ecocomposite harmonized with environment and accorded with requirement of benignly friendly environment.

Reinforcing effects of modified Kevlar~ fiber on the mechanical properties of wood-flour/polypropylene composites

Kevlar fiber （KF） is a synthesized product with strong mechanical properties. We used KF as a reinforcement to improve the mechanical properties of wood-flour/polypropylene （WF/PP） composites. KF was pretreated with NaOH to improve its compatibility with the thermoplastic matrix. Maleated polypropylene （MAPP） was used as a coupling agent to improve the interfacial adhesion between KF, WF, and PP. Incorporation of KF improved the mechanical properties of WF/PP composites. Treatment of KF with NaOH resulted in further improvement in mechanical strength. Addition of 3% MAPP and 2% hydrolyzed KF （HKF） led to an increment of 93.8% in unnotched impact strength, 17.7% in notched impact strength, 86.8% in flexure strength, 50.8% in flexure modulus, and 94.1% in tensile strength compared to traditional WF/PP composites. Scanning electron microscopy of the cryo-fractured section of WF/PP showed that the HKF surface was rougher than the virgin KF, and the KF was randomly distributed in the composites, which might cause a mechanical interlocking between KF and polypropylene molecules in the composites.

The properties of flax fiber reinforced wood flour/high density polyethylene composites

Flax fiber(FF) was used to reinforce wood flour/high density polyethylene composites(WF/PE).WF/PE particles were uniformly mixed with FF via high-speed mixing and then extruded with a single screw extruder to prepare FF reinforced WF/PE composites(FF/WF/PE).Mechanical testing,dynamic mechanical analysis,scanning electron microscopy(SEM),creep measurement and Torque rheology were used to characterize the resulting composites.The results indicate that the mechanical performance of the composites could be remarkably improved by adding a limited amount of FF.The flexural strength and modulus increased by 14.6 and 51.4%,respectively(FF content of 9 wt%),while the unnotched impact strength could be increased by 26.5%(FF content of12 wt%).The creep resistance and toughness of thecomposite was markedly improved without changing the plastic content of the composite material.

Determination of fiber length and juvenile and mature wood zones in Acer velutinum Boiss.trees grown in Iran

In our investigation we studied fiber lengths and the transition age from juvenile to mature wood in Acer velutinum Boiss. For this purpose, samples from three normal maple trees at a Noshahr site in northern Iran were selected. Disks were cut at breast height. Test samples were taken along a radial direction from the pith to the bark, accounting for every ring during a 48-year period. We used the Franklin method to distinguish between fibers of juvenile and mature wood. The results show that the fiber length in- creased along the radial direction from the pith to the bark. The transition age between juvenile and mature wood was determined at the 14th annual ring from the pith.

Effects of carbonization temperatures on microstructure of carbon fiber precursors prepared from liquefied wood

In order to enlarge the utilization field of wood and decrease the costs of carbon fibers, carbon fiber precursors from liquefied wood were prepared by soaking liquefied wood in a solution containing hydrochloric acid and formaldehyde, after melt-spinning by adding hexamethylenetetramine. The microstructure evolution of the precursor during carbonization was studied by FTIR, X-ray analysis and Raman spectroscopy. The results show that precursors from liquefied wood above 400℃had diffraction peaks corresponding to the （100） crystal plane. When the carbonization temperature reached 500℃, Raman spectroscopy showed the D peak at wave number of 1360 cm^-1 and the G peak at 1595 cm^-1. By increasing the carbonization temperature, the microstructure of the precursors became more ordered. Although the structure of the precursor changed at 500 and 800℃, the peaks at 1632 and 1454 cm^-1 corresponding to the characteristic vibrations of aromatic rings, remained during carbonization. This implies that the precursor from liquefied wood cannot be easily formed into graphite.

Static Bending Creep Properties of Glass Fiber Surface Composite Wood

To study the static bending creep properties of glass fiber reinforced wood,glass fiber reinforced poplar(GFRP)specimens were obtained by pasting glass fiber on the upper and lower surfaces of Poplar(Populus euramevicana,P),the performance of Normal Creep(NC)and Mechanical Sorptive Creep(MSC)of GFRP and their influencing factors were tested and analyzed.The test results and analysis show that:(1)The MOE and MOR of Poplar were increased by 17.06%and 10.00%respectively by the glass fiber surface reinforced composite.(2)The surface reinforced P with glass fiber cloth only exhibits the NC pattern of wood and loses the MSC characteristics of wood,regardless of the constant or alternating changes in relative humidity.(3)The instantaneous elastic deformation,viscoelastic deformation,viscous deformation and total creep deflection of GFRP are positively correlated with the stress level of the external load applied to the specimen.Still,the specimen’s creep recovery rate is negatively correlated with the stress level of the external load applied to the specimen.The static creep deflection and viscous deformation of GFRP increase with the increase of the relative humidity of the environment.(4)The MSC maximum creep deflection of GFRP increased by only 7.41%over the NC maximum creep deflection,but the MSC maximum creep deflection of P increased by 199.25%over the NC maximum creep deflection.(5)The Burgers 4-factor model and the Weibull distribution equation can fit the NC and NC recovery processes of GFRP well.

Effects of different modifiers on the properties of wood-polymer composites

Wood-polymer composites (WPC) were prepared from wood fiber and four kinds of plastics such as PE, PS, ABS, and SAN. The effects of different modifiers on the mechanical properties of the composites were studied. The results showed modifiers could raise the bonding strength of wood fiber with polymer and improve the mechanical properties of the composites. Different modifiers had different effects on the properties of wood-polymer composites, and comparatively the modifier of isocyanate produced a better result. Wood-polymer composite takes not only the advantages of both wood fiber and polymer, but waterproof, dimensional stability and dynamic strength are also significantly improved. Key word Wood fiber - Thermoplastic polyester - Wood-polymer composites - Modifier - Mechanical properties CLC number TB332 Document code A Foundation item: This study was supported by the Harbin Technology Tackle Key Plan (Development Research of Wood-Polymer Composites with High Wood Matrix) and by Heilongjing Nature Science Fund (Composite Mechanism Study of the Wood Polymer).Biography: XU Min (1963-), Female, Associate professor in Material Science and Engineering College, Northeast Forestry University, Harbin 150040, P. R. China.Responsible editor: Chai Ruihai

Determination of Some Physical and Mechanical Properties of the Wood-Based Panels Modified by Acrylic Textile Fiber

In this research, a series of wood-based panels were produced by using wood chips [beech (Fagus Sylvatica L.) and Scotch pine (Pinus sylvestris L.)] as wastes of wood-working workshops and acrylic fibers as wastes of textiles factory. Four kinds of different panels (Eltapan I, II, III and IV) were obtained by mixing these components in different composition (0%, 25% and 50%). Some physical and mechanical properties of the samples taken from these panels were determined in accordance with ASTM D1037-12 and ASTM-C 1113. The values were compared to properties of industrially produced chipboard. As a result, the textile fibers used as additive material reduced density, thermal conductivity and bending resistance of wood panel and increased dimensional stability of wood panel.

Effects of wollastonite nanofibers on fluid flow in medium-density fiberboard

We studied the effect of wollastonite nanofibers on fluid flow in medium-density fiberboard （MDF）. Nanowollastonite （NW） was applied in MDF at 10 %, based on the dry weight of wood fibers. We also tested chicken feathers as an additive to the matrix at 5 and 10 % by weight. The weight of feathers was reduced from the wood fibers to keep the density of the panels constant （0.66 g cm-3）. Wollastonite nanofibers acted as filler in the matrix and significantly decreased gas and liquid perme- ability. Higher thermal conductivity of the N-W-treated MDF-mats resulted in a better cure of resin, and conse- quently more integrity in the composite-matrix and lower permeability. The water-repellant property of wollastonite also contributed to the decrease in liquid permeability. Feathers reduced gas and liquid permeability due to the hydrophobic nature of keratin, as well as its formation as a physical barrier towards passing of fluids. Ten percent feather content proved too high and some checks and cracks occurred in the core of the panels after hot-pressing. Panels with 5 %-feather content resulted in both lower fluid flow and adequate physical integrity in the core sec- tion of the MDF-matrix.

Effect of Photostablizers on Surface Color and Mechanical Property of Wood-flour/HDPE Composites after Weathering

The effects of photostabilizers of ultraviolet absorbers （UVA）, hindered amine light stabilizer （HALS） and pigment on surface color change and mechanical properties of weathered wood-flour/ polyethylene （HDPE） composites were investigated. After being added UVA with high UV absorbance, the WPC exhibites better ability to resist color fading and mechanical property loss. High molecular weight HALS is found to be the most effective in controlling long term fading and yellowing changes. Pigments cover the composites for remaining the original color after weathering regardless of less contribution to mechanical property. Addition of photostabilizer and pigment together show great synergism in decreasing color fading and flexural property loss.

Size effect on longitudinal MOE of microtomed wood sections and relevant theoretical explanation

It has been repeatedly observed that the mechanical properties of microtomed wood sections are significantly lower than those of samples of normal size, but few investigations have been conducted to deal with this topic, especially based on theoretical approaches. We measured the longitudinal MOE of Chinese fir on microtomed sections ranging in thickness from 70 to 200 μm and compared these with the values of samples of normal size. The results indicate that the MOE of microtomed wood sections increases with thickness from 70 to 200 μm, but is significantly less than that of normal samples. A size effect coefficient of 2.63 is inferred based on statistical data for samples of normal size and 200 μm thick microtomed sections. Finally, an explanation based on a complete shear restraint model of cell walls and a single fiber multi-ply model is proposed for the size effect on stiffness of microtomed wood sections.

三种木材纤维微细结构分析及制浆性能研究

制浆造纸企业纤维原料供应持续紧缺,如何拓宽原料来源渠道是造纸企业普遍关心的问题。为缓解造纸原料短缺的问题,采用柳树、美人梅、猕猴桃作为制浆造纸原料,分析三种木材原料的组分、纤维长度、宽度以及表面形态,解析纤维的红外结构、元素组成、结晶度、热稳定性。柳树、美人梅、猕猴桃纤维的长度范围分别为:0.1 mm~1.2 mm,0.1 mm~1.0 mm,0.1 mm~2.0 mm,平均宽度分别为16.5μm,15.7μm,25.1μm,长宽比分别为27.2,30.6,35.9猕猴桃纤维的长度范围、宽度和长宽比均优于柳树和美人梅,具有造纸的潜力。通过硫酸盐法蒸煮实验发现柳树、美人梅、猕猴桃三种木材具有较高的制浆得率,纸张物理性能良好,能够满足生产质量的要求,可以替代部分现有的纤维原料,以减轻造纸工业对木材原料需求的压力,缓解制浆造纸原料短缺的问题。