Nanolignin,a Coupling Bio-Agent for Wood-Plastic Composites

The influence of nanolignin coupling bio-agent on some characteristics of polypropylene-wood flour composites was studied.Thus,nanolignin was prepared by the acidic method,and then different ratios of it(0,1,3 and 5 wt%)were added to a polypropylene-wood flour mixture.After mechanically mixing wood flour,nanolignin,and polypropylene,the mixture was injection molded.ASTM methods were used to measure the structural properties of nanolignin,and prepared composites’water absorption,thickness swelling,bending modulus,and bending,tensile and impact strengths.Transforming the original lignin to nanolignin did not change the chemical bonds of the material.The addition of nanolignin yielded improved mechanical and physical properties of the composites prepared.Higher strength and dimensional stability are presented by nanolignin-containing composites when comparing them with those prepared with normal lignin.Nanolignin was shown by SEM(Scanning Electron Microscope)observation to be uniformly dispersed within the polymer matrix.Wood polymer composites(WPCs)with nanolignin exhibited comparable properties with the control samples prepared using maleic anhydride polypropylene(MAPP).

Performance Analysis of Plant Shells/PVC Composites under Corrosion and Aging Conditions

To make full use of plant shellfibers(rice husk,walnut shell,chestnut shell),three kinds of wood-plastic com-posites of plant shellfibers and polyvinyl chloride(PVC)were prepared.X-ray diffraction analysis was carried out on three kinds of plant shellfibers to test their crystallinity.The aging process of the composites was conducted under 2 different conditions.One was artificial seawater immersion and xenon lamp irradiation,and the other one was deionized water spray and xenon lamp irradiation.The mechanical properties(tensile strength,flexural strength,impact strength),changes in color,water absorption,Fourier transform infrared spectroscopy(FTIR),and microstructures of the composites before and after the two aging experiments were analyzed.The results showed that the chestnut shell had the highest crystallinity,which was 42%.The chestnut shell/PVC composites had the strongest interface bonding,the least internal defects,and the best general mechanical properties among the three composites.Its tensile strength,bending strength and impact strength were 23.81 MPa,34.12 MPa,and 4.32 KJ·m^(-2),respectively.Comparing the two aging conditions,artificial seawater immersion and xenon lamp irradiation destroyed the quality of the combination of plant shellfibers and PVC,making the internal defects of the composites increase.This made the water absorption ability and changes in the color of the composites more obvious and led to a great decrease in the mechanical properties.The general mechanical properties of the chestnut shell/PVC composites were the best,but their water absorption ability changed more obviously.

Preliminary study of the effects of EVA coupling agents on properties of wood-plastic composites

As a hot-melt adhesive, ethylene-vinyl-acetate （EVA） has been used in many industrial applications. But studies of the application of EVA in wood-plastic composites （WPC） are relatively few, so we have investigated the proposition of whether EVA is a suitable coupling agent for WPC or not. The results show that EVA with 8% VA is not a suitable coupling agent, because it reduces the mechanical properties of WPC without any significant effect on its physical properties. With an increase in the amount of wood powder, the mechanical properties of WPC decrease and the ability of water absorption of WPC increases.

Chemical characterization of smoke from the production process of wood-plastic composites

The chemical composition of unpleasant smell, emitted from the production process of wood-plastic composites using Manchurian ash sawdust （Fraxinus mandschurica Rupr.） and polypropylene powder as the raw material, was investigated. Wood sawdust and polypropylene powder were subjected to heat treatment to 290℃ during 8 min （the conditions were similar to those employed on an industrial scale）. The emitted compounds were collected and analyzed by gas chromatography-mass spectrometry （GC-MS）. The analytical results showed that the unpleasant smell was emitted from the pyrogenation of wood sawdust rather than from the polypropylene powder. Nine types of compounds （hydrocarbons, ethers, phenols, aldehydes, ketones, alcohols, acids and their derivatives, furan and its derivatives, and nitrogen-containing compounds） were collected in the gas phase during heating. Among those 126 components detected by GC-MS, 112 compounds were identified.

Property changes of wood-fiber/HDPE composites colored by iron oxide pigments after accelerated UV weathering

Four kinds of iron oxide pigments were added into wood-fiber/high-density-polyethylene composites （WF/HDPE） at three different concentrations, to determine the effects of pigments on the changes in the color and mechanical properties of the composites before and after UV accelerated weathering. HDPE, wood fibers, pigments and other processing additives were dry-mixed in a high-speed mixer. The mixtures were extruded by two-step extrusion process with a self-designed twin-screw/single-screw extruder system. Color of the samples was determined according to CIE 1976 L^＊a^＊b^＊ system by a spec- trophotometer and the bending properties were tested to evaluate the mechanical properties before and after accelerated UV weathering. The result shows that the modulus of elasticity of WF/HDPE did not obvi- ously changed after incorporating with the pigments, but the bending strength increased. After accelerated aging for 2000 h, both color and mechanical properties significantly changed. Iron oxide red and black performed better than the other two pigments, and the pigments dosage of 2.28% in the composites is favourable.

Preliminary study of viscoelastic properties of MAPP-modified wood flour/polypropylene composites

Viscoelastic properties of maleated polypropylene （MAPP）-modified wood flour/polypropylene composites （WPC） were investigated by both a compression stress relaxation method and dynamic mechanical analyses （DMA）. Three wood to polymer ratios （40：60, 60：40, and 80：20） and five MAPP loading levels （0, 1, 2, 4 and 8%） were used to study their effects on the viscoelastic prop- erties of MAPP-WPC. The results show that： 1） higher wood to polymer ratio corresponds to higher stress relaxation levels for unmodified WPC. The modification with MAPP has an obvious effect on the stress relaxation of MAPP-WPC at higher wood to polymer ratios （60：40 and 80：20）, but almost no effect at the 40：60 wood to polymer ratio. The optimal MAPP loading level for the wood to polymer ratio of 60：40 appears at 1%; 2） the storage modulus reaches its maximum at a MAPP loading level of 1% for wood to polymer ratios of 40：60 and 60：40, while for the 80：20 wood to polymer ratio, a higher storage modulus is observed at higher MAPP loading levels, which is quite consistent with the stress relaxation results. The results suggested that a suitable loading level of MAPP has a positive effect on the viscoelastic properties of WPC at higher wood to polymer ratios. Excessive MAPP loading would have resulted in adverse effects.

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.

Effect of an antioxidant on the life cycle of wood flour/polypropylene composites

This study assessed the life cycle of biocomposites with antioxidants by repeated processing.The effects of antioxidants on the life cycle of wood flour/polypropylene(PP)composites were determined by analyzing their mechanical and thermal properties.The composites were repeatedly processed for seven times with pelletizing and extruding.An antioxidant,pentaerythritoltetrakys 3-(3,5-ditert-butyl-4-hydroxyphenyl)propionate,was used.The mechanical strength of the biocomposites decreased after reprocessing.Fourier transformed infrared analysis showed that thermo-oxidative aging occurred during reprocessing.The thermal performance of the resulting composites decreased because of reprocessing.Wood flour/PP has a long lifetime and antioxidants can slow the thermo-oxidative and mechanical degradation during reprocessing.

Study on Water Resistance of Polydopamine Treatment Wood Flour/Polypropylene Composites

This paper aims to investigate the water absorption of wood flour/polypropylene composites and its effects on dimensional stability and crystallization properties. Wood-plastic composites (WPCs) makes using polydopamine modified wood flour (WF-D), virgin polypropylene, maleic anhydride-grafted polypropylene (MA) and antioxidant, by using hot-pressing moulding. Water absorption (WA), thickness swelling (TS) and failure of flexural properties of the composites have studied for a range of immersion times. It is found that the WA and TS have increased with WF content and immersion time. The water absorption and thickness swelling of WPCs are 0.85% and 0.99%, respectively, after 8 days immersion. With the prolonging of immersion time, the impact strength, flexural strength and flexural modulus of WPCs increase first and then decrease. The impact strength decreases from 3.32 kJ/m2 to 2.94 kJ/m2, the retention rate is 88.55%;the flexural strength and flexural modulus by 68.58 Mpa and 3.92 Gpa, respectively. WPCs crystallization and thermal properties decrease slightly. Microstructures of the composites are examined to understand the mechanisms for the wood-plastic interaction which affects the water absorption and thickness swelling. Our work demonstrates that using polydopamine treatment wood flour for preparing WPCs can be an efficient way to improve the water resistance of WPCs.

2023年中国木塑地板、石木塑地板等出口情况及贸易壁垒分析

依据中国海关数据,分析2023年中国木塑地板、石木塑地板等地板产品出口数量、出口金额、出口市场以及中国出口省份等情况,阐述了木塑地板、石木塑地板等出口涉及的贸易壁垒。2023年中国出口石木塑地板、PVC卷材地板和LVT地板等含PVC聚合物的地板产品为460.01万t,同比2022年降低9.20%;出口户外用木塑地板等含PP、PE等聚合物的地板产品58.49万t,出口量略有下降,但基本稳定。北美洲国家是该产品的主要出口市场,且占比较高;江苏省和浙江省是中国生产和出口大省。中国木塑地板和石木塑地板出口主要受美国“337调查”和“301条款”贸易壁垒影响。

木粉含量对PE-WPCs射流等离子体处理时效性的影响

采用空气射流等离子放电技术对木粉/聚乙烯复合材料(PE-WPCs)进行表面处理,以改善其胶接性能,通过接触角和胶接强度测试、傅里叶红外光谱(FTIR)和X射线光电子能谱(XPS)方法等分析研究了木粉含量对PE-WPCs等离子体处理时效性的影响.结果表明:经射流等离子体处理后,PE-WPCs表面产生了含氧极性基团,表面接触角减小,胶接强度明显提高;随着放置时间的延长,处理后PE-WPCs表面极性基团数量减少,表面接触角增大,胶接强度略有下降,表现出一定的处理时效性;PE-WPCs木粉含量越高,处理时效性越小;尽管存在时效性,但处理后PE-WPCs的胶接强度仍远高于未处理PE-WPCs.

Effect of Different Reinforcing Fillers on Properties,Interfacial Compatibility and Weatherability of Wood-plastic Composites

Utilization of biochar in plastic based blends offers a sustainable way to renewable materials as well as value-added use of wood waste.To investigate the interfacial compatibility and weatherability properties of biochar composites,four types of Wood-Plastic Composites(WPC)were prepared by an extrusion process.The mechanical properties,water absorptions,thermal and viscoelastic properties,and rheological behavior of the composites were also evaluated.The decolorizing carbon(NA)composite melts showed the higher modulus and viscosity,indicating better melt strength.The NA composites performed the best in tensile properties(strength of 2&6 MPa and modulus of 3.4 GPa)and had strong interfacial interaction between particles and the matrix.The degree of HDPE crystallinity in the biochar and carbon composites decreased relative to Douglas-fir(DF)composites,while the thermal properties of the composites improved compared with DF composites.For the water resistance,the DF composites displayed the highest water absorption(3.7%)and thickness swell(2.9%).During accelerated weathering tests,longer exposure time increased the color change and lightness,especially for DF composite.NA and biochar composites resulted in improved photostability.This study opens up a pathway to utilize effectively the renewable biochar as reinforcing filler in WPC in outdoor applications.

Effect of wood dust type on mechanical properties, wear behavior, biodegradability, and resistance to natural weathering of wood-plastic composites

The present work reports the inclusion of different proportions of Mango/Sheesham/Mahogany/Babool dust to polypropylene for improving mechanical,wear behavior and biodegradability of wood-plastic composite(WPC).The wood dust(10%,15%,20%by weight)was mixed with polypropylene granules and WPCs were prepared using an injection molding technique.The mechanical,wear,and morphological characterizations of fabricated WPCs were carried out using standard ASTM methods,pin on disk apparatus,and scanning electron microscopy(SEM),respectively.Further,the biodegradability and resistance to natural weathering of WPCs were evaluated following ASTM D5338-11 and ASTM D1435-99,respectively.The WPCs consisting ofBabool and Sheesham dust were having superior mechanical properties whereas the WPCs consisting of Mango and Mahogany were more wear resistant.It was found that increasing wood powder proportion results in higher Young's modulus,lesser wear rate,and decreased stress at break.The WPCs made of Sheesham dust were least biodegradable.It was noticed that the biodegradability corresponds with resistance to natural weathering;more biodegradable WPCs were having the lesser resistance to natural weathering.

Decorative Wood Fiber/High-Density Polyethylene Composite with Canvas or Polyester Fabric

Wood-plastic composite is an environmentally friendly material,due to its use of recycled thermoplastics and plant fibers.However,its surface lacks attractive aesthetic qualities.In this paper,a method of decorating wood fiber/high-density polyethylene(WF/HDPE)without adding adhesive was explored.Canvas or polyester fabrics were selected as the surface decoration materials.The influence of hot-pressing temperature and WF/HDPE ratio on the adhesion was studied.The surface bonding strength,water resistance,and surface color were evaluated,and observation within the infrared spectrum and under scanning electron microscopy was used to analyze the bonding process.The results showed that the fabric and WF/HDPE substrate could be closely laminated together depending on the HDPE layer accumulated on the WF/HDPE surface.The molten HDPE matrix penetrates canvas more easily than polyester fabric,and the canvasveneered composite shows a greater bonding strength than does the polyester fabric-veneered composite.A higher proportion of the thermoplastic component in the substrate improved the bonding.When the hot-pressing temperature exceeded 160°C,the fabric-veneered WF/HDPE panels had greater water resistance,although the canvas fabric changed more obviously in terms of fiber shape and color,compared with the polyester fabric.For the canvas fabric,140°C–160°C was a suitable hot-pressing temperature,whereas 160°C–180°C was more suitable for polyester fabric.The proportion of the thermoplastic component in the composite should be not less than 30%to achieve adequate bonding strength.

Mechanical Properties of a Wood Flour-PET Composite Through Computational Homogenisation

This work proposes to study the effective elastic properties(EEP)of a wood-plastic composite(WPC)made from polyethylene terephthalate(PET)and Chilean Radiate pine’s wood our,using nite element simulations of a representative volume element(RVE)with periodic boundary conditions.Simulations are validated through a static 3-point bending test,with specimens obtained by extruding and injection.The effect of different weight fractions,space orientations and sizes of particles are here examined.Numerical predictions are empirically conrmed in the sense that composites with more wood our content and bigger size,have higher elastic modulus.However,these results are very sensitive to the orientation of particles.Voigt and Reuss mean-eld homogenisation approaches are also given as upper and lower limits.Experimental tests evidence that exural strengths and ultimate tensile elongations decrease respect to 100%PET,but these properties can be enhanced considering particle-size distributions instead of a xed size of wood our.

热可逆性共价交联木塑复合材料的制备及力学性能

为提高木塑复合材料(wood-plastic composites,WPCs)的力学性能,基于酯交换反应,以木粉、E51环氧树脂和邻苯二甲酸酐为原料,通过热压成型工艺制备热可逆性共价交联木塑复合材料(TRC-WPCs),探究环氧与酸酐量比、热压工艺参数和循环加工对TRC-WPCs力学性能的影响。当环氧与酸酐的量比为1∶1,热压时间为30 min、热压温度为150°C、热压压力为12 MPa时,TRC-WPCs的力学性能最优,其拉伸强度、拉伸模量、弯曲强度和弯曲模量分别为47.3 MPa、9.3 GPa、79.2 MPa和8.9 GPa,比相同木粉含量的高密度聚乙烯基WPCs高出282%、204%、305%和245%;且循环加工后其弯曲强度和弯曲模量保持率为67.8%和84.2%,实现了TRC-WPCs的高强度化,并且高温下可循环加工。

浅析木塑复合材料在现代园林景观中的应用

木塑复合材料即为木质或纤维素材料和热塑性塑料混合所制备的材料,不但具备有塑料的应用优势,也具备木材部分使用性能,因此得到了广泛应用。我国从20世纪90年代末开始针对木塑复合材料实施研究,当前已经得到政府以及市政园林部门对其环保性能以及应用优势的认可。该文重点分析木塑复合材料在现代园林景观中的应用。

No-formaldehyde Wood-plastic Composite Plywood in China

As a new product invented by the Research Institute of Wood Industry, no-formaldehyde wood-plastic composite plywood is the harvest of the cross-study on wood-plastic composite and plywood industry, It has no formaldehyde emission, with an excellent environment-friendly performance and a good bonding quafity. This paper analyses the strongpoints and market of this wood-plastic composite plywood.

木材—热塑性塑料复合材料的进展

回顾了木材 -塑料复合材料 (简称WPC)的发展历史 ,介绍了WPC的生产工艺方法 ,总结了木塑复合材产品性能中的不足和生产中存在的问题 ,展望了其未来的发展趋势和前景。

苯乙烯(St)/甲基丙烯酸甲酯(MMA)/丙烯腈(AN)三元接枝共聚塑合木研制

本文报道了采用苯乙烯／甲基丙烯酸甲酯／丙烯腈（ＳＭＡ）三元共聚单体浸入木材细胞壁与激活的纤维素进行接枝聚合反应，构成新型的高分子复合材料（ＳＭＡ－ＷＰＣ），经物理机械性能、吸水性、耐酸性检测，该材料硬度比素木提高了２０％～３５％，抗压强度提高了３５％～４５％，经９８％浓硫酸３天浸泡，重量损失率下降２２％，而在水介质８天浸渍，吸水率下降５０％，并通过扫描电镜观察了塑化前后的微观结构。