Procedure effect on the physical and mechanical properties of the extruded wood plastic composites

This article investigates the effect of raw material preparation on the mechanical and physical properties in wood‐plastic composite (WPC) production. Four possible procedures in material preparation to obtain a determined level of wood content are: (i) to use and feed raw materials in the same ratio of the desired composition (single stage), (ii) to use the batch of granules of the same composition (two‐stage), (iii) to add wood to the batch of granules having a lower wood content, (iv) to add polymer to the batch of granules having a higher wood content. The main question then is that, while it is economically attractive to use granules of a fixed wood content in all productions, whether there are noticeable differences in final properties of the products. The examined compositions were 50, 60, and 70 wt% of wood content which are considered as highly filled WPCs and mainly used in the WPC markets. Thus, 12 sets of WPC profiles were manufactured and the processing conditions (temperature, pressure, and outlet velocity) recorded. The flexural properties, impact strength, density, and water uptake were measured. Results revealed that in the production of WPCs with 50 and 70 wt% of wood content, using the WPC granules with the same composition yields better physical and mechanical properties. However, for producing WPC with 60 wt% of wood content, using WPC granules with 70 wt% of wood and adding appropriate amount of polymer exhibit better results. POLYM. COMPOS. 34:1349–1356, 2013. © 2013 Society of Plastics Engineers     

木塑复合材料的热氧化规律研究

以聚丙烯(PP)和木粉为主要原料制备了木塑复合材料(WPC),用差示扫描量热法（DSC）和热重分析（TG）研究了WPC及其主要原料PP、木粉的热氧化曲线特征,并研究了木粉、抗氧剂对WPC氧化诱导时间的影响。结果表明,在含有抗氧剂1010的条件下,PP和WPC都不会被显著氧化,而当抗氧剂1010消耗完毕后（氧化诱导时间之后）,PP和WPC都会发生明显热氧化而使DSC曲线上出现放热峰,同时使TG曲线上出现快速热失重;抗氧剂对提高木粉的热稳定性没有显著效果;在WPC中加入抗氧剂硫代二丙酸二月桂酯（DLTP）对提高WPC的热稳定性具有显著效果。     

Wood–polymer composites prepared by the in situ polymerization of monomers within wood

Wood–polymer composites (WPCs) were prepared from poplar wood (P. ussuriensis Komarov) in a two‐step procedure. Maleic anhydride (MAN) was first dissolved in acetone and impregnated into wood; this was followed by a heat process; and then, glycidyl methacrylate (GMA) and styrene (St) were further impregnated into the MAN‐treated wood, followed by a second thermal treatment. Finally, the novel WPC was fabricated. The reactions occurring in the WPC, the aggregation of the resulting polymers, and their interaction with the wood substrate were analyzed by scanning electron microscopy, Fourier transform infrared spectroscopy, X‐ray diffraction, and dynamic mechanical analysis. The performance of WPC was also evaluated in terms of the mechanical properties and durability, which were then correlated with the structural analysis of the WPC. The test results show that MAN and GMA/St chemically reacted with the wood cell walls in sequence, and the quantity of hydroxyl groups in the wood cell walls was evidently reduced. Meanwhile, St copolymerized with GMA or MAN, and the resulting polymers mainly filled in the wood cell lumen in an amorphous form, tightly contacting the wood cell walls without noticeable gaps. As a result, the mechanical properties, decay resistance, and dimensional stability of the WPC were remarkably improved over those of the untreated wood, and its glass‐transition temperature also increased. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

再生塑料与木质纤维复合材料的研制

采用木粉和再生塑料为主要原料,进行塑料与木质纤维复合材料的配方研究,通过实验确定了木粉最佳干燥条件。考察了不同相容剂用量、木粉用量对复合材料性能的影响,得到了再生塑料与天然纤维复合材料的最佳配方。     

MAPE含量对PE木塑复合材料冲击强度的影响

以高密度聚乙烯(PE-HD)和马来酸酐接枝聚乙烯(MAPE)共混物为塑料基体,以木粉(WF)为填料,采用压制成型法制备了木塑复合材料。研究了MAPE含量对塑料基体和木塑复合材料冲击强度的影响。结果表明,MAPE含量对MAPE/PE-HD塑料基体和木塑复合材料的冲击强度影响显著;保持MAPE和PE-HD的总含量不变时,当木粉含量为30 %时,木塑复合材料的冲击强度随MAPE含量的增大而逐渐减小;当木粉含量为70 %时,木塑复合材料的冲击强度随MAPE含量的增加而逐渐增大。     

木粉和抗氧剂对废旧PE-HD/沙柳复合材料性能的影响

以沙柳木粉和废旧高密度聚乙烯（PE-HD）为原料,采用模压法制备了木塑复合材料（WPC）。考查了沙柳木粉和抗氧剂对WPC性能的影响。结果表明,沙柳木粉加入量为0~70 %（质量分数,下同）时,WPC的静曲强度呈先上升后下降的趋势,弹性模量和拉伸强度分别呈上升和下降的趋势;沙柳木粉降低了WPC的热稳定性,使热分解起始温度降低;随加入量的增加,WPC的储能模量（E′）和损耗模量（E″）曲线均呈上升趋势,损耗因子（tanδ）曲线呈下降趋势,E″曲线内耗峰的位置向高温方向移动;抗氧剂1010加入量为0~0.5 %时,WPC的静曲强度、弹性模量和拉伸强度均呈不同程度的先上升后下降的趋势;当抗氧剂加入量为0.2 %和0.3 %时,E′和E″相对较高。     

Effect of Fiber Origin,Proportion, and Chemical Composition on the Mechanical and Physical Properties of Wood-Plastic Composites

This study assessed the potential of wood residues as fiber sources for wood-plastic composites (WPC) and examined the impact for intrinsic fiber properties on strength development. Sawmill sawdust, underused wood species, bark, composite panel, and pulp and paper sludge residues were sampled. Fibers were characterized for cellulose content, ash content, and fiber aspect ratio. WPC samples were formed by twin-screw extrusion compounding, followed by injection molding at three fiber proportions. WPC mechanical properties, water uptake, and water swelling increased with increasing fiber proportion, whereas tenacity decreased. WPC made with residues had lower mechanical and physical properties than those made with clean wood, with some exceptions. Kraft sludge produced one of the best WPC formulations in terms of thickness swell, water swelling, tensile strength, and impact energy. Deinking sludge produced the toughest and the most dimensionally stable WPC. Panel industry residues formed roughly similar WPC to those made with clean wood. Bark led to poorest WPC in terms of mechanical properties. High correlation coefficients were found between cellulose content, wood content, and all WPC properties except impact energy. However, the correlations between aspect ratio and the WPC were insignificant.     

Studies of physico–mechanical properties of wood and wood plastic composite (WPC)

An attempt has been made to improve the quality of low grade wood through radiation induced wood plastic composite (WPC) formation in order to use these low grade woods as substitutes for high grade wood. Six kinds of local woods of Bangladesh (simul, korai, mango, jack fruit, teak, and garjon) were investigated. Both soft and hard wood varieties of these were selected. Ten vinyl monomers were used for the WPC. Improvement in the quality of wood was ascertained by determining change in physico—mechanical properties of wood. These properties were tensile strength, Young's modulus, and dimensional stability. Among all the woods investigated, simuls exhibited the best performance for WPC formation. It was found that the tensile strength and Young's modulus of WPC increased about 1.6 and 1.5 times, respectively, as compared with the strength and modulus those of untreated wood.     

木粉疏水改性对HDPE基木塑复合材料性能的影响

采用一种操作简便且易于工业推广的方法对木粉进行疏水改性,具体过程为：将3种可热聚合的单体,即甲基丙烯酸甲酯（MMA）、甲基丙烯酸丁酯（BMA）和苯乙烯（St）均匀喷洒在木粉上,经过预热处理后,与配方中其他组分,如高密度聚乙烯（HDPE）和马来酸酐接枝聚乙烯（MAPE）等通过高速混合机混合均匀,采用双螺杆挤出机造粒后,注射制备木塑复合材料（WPC）样条,测试其力学性能。另外,考察了疏水改性对WPC接触角、维卡软化温度、洛氏硬度、吸水性能、热性能的影响规律。结果表明：疏水改性后WPC的接触角增大,木粉和HDPE的界面相容性改善,力学性能得到明显提高。其中,当MMA、BMA和St的添加量为3%时,WPC的力学性能最好,与疏水改性前相比,弯曲强度分别提高了17.3%、26.3%和27.5%,弯曲模量分别提高了24.4%、24.4%和26.0%,冲击强度分别提高了54.7%、57.7%和60.5%。 此外,疏水改性后WPC的维卡软化温度、洛氏硬度、耐水性和耐热性也得到改善。     

Dimensional stability of wood–polymer composites

Wood–polymer composites (WPC) were prepared by impregnation of polymeric monomers in wood and in situ polymerization. Three polymeric chemicals were chosen for this study: methyl methacrylate (MMA), hydroxyethylene methacrylate (HEMA), and ethylene glycol dimethacrylate (EGDMA). The effects of polymeric monomers and their combinations on moisture adsorption (M), anti–moisture adsorption efficiency (AME), liquid water uptake (D), water repellency efficiency (WRE), longitudinal, radial, tangential, and volumetric swelling properties (S) after soaking, and antiswelling efficiency (ASE) were investigated. It was found that M was different for different methacrylate combinations and depended not only on the composition of the impregnants, but also on wood properties. Liquid water uptake was similar regardless of the formulation of the WPC. Wood–polymer composites with high MMA content displayed enhanced dimensional stabilities, but WPCs with high HEMA content did not. Tangential and volumetric ASEs were strongly dependent on the type of treatment. Mold growth tests showed that wood treated with HEMA alone had no surface mold growth, and wood treated with MMA alone also showed less mold growth than did the control samples. © 2006 Wiley Periodicals, Inc. J Appl PolymSci 102: 5085–5094, 2006     

增容剂对再生聚丙烯/木粉复合材料性能的影响

以再生聚丙烯(PP)、锯末木粉为原料,采用双螺杆挤出机挤出造粒制备了塑木复合材料。研究了增容剂马来酸酐接枝PP(PP-g-MAH)用量对再生PP/木粉复合材料吸水性、拉伸性能、弯曲性能、冲击性能、硬度和热变形温度等性能的影响,并采用扫描电子显微镜分析了材料的断面形态。结果表明,PP-g-MAH可以增加木粉与PP的界面结合力,提高复合材料的性能,其最佳用量为6～9份。     

几种木塑复合材料的性能对比

研究了木粉及界面增容剂含量对木塑复合材料(WPC)力学性能的影响,分析了增容剂对WPC熔融性能的变化。使用木粉填充可提高不同树脂基WPC的模量,但却降低了HDPE基WPC的拉伸强度及HDPE基、PP基WPC的弯曲强度。     

木塑复合材料的光降解与光稳定

介绍了国内外木塑复合材料的发展现状,分析了木塑复合材料的光降解机理,指出木塑复合材料的光稳定必须综合考虑木材和塑料两方面的因素,对目前木塑复合材料光稳定的可行途径进行了讨论,并展望了国内外木塑复合材料的发展趋势。     

Modification of rubber wood with styrene in combination with diethyl allyl phosphate as the flame‐retardant agent

Rubber wood (Hevea brasiliensis) polymer composite was prepared using styrene as the monomer in combination with diethyl allyl phosphate (DEAP) to improve flame‐retardant property. DEAP was synthesized, characterized and incorporated into wood with styrene. The polymerization was accomplished by catalyst heat treatment using AIBN as the catalyst. The properties of wood–polymer composites (WPC) like water absorption, swelling in water, hardness, modulus of elasticity (MOE), modulus of rupture (MOR) etc. were improved on treatment. The thermal degradation behavior of WPC was evaluated using thermogravimetric analysis (TGA) and the flammability of the WPC was evaluated using the limiting oxygen index (LOI) test. It was observed that fire retardancy of WPC improved on incorporation of DEAP. FTIR spectroscopy and SEM study showed the interaction between wood and the polymers. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

Wood–polymer composites made with acrylic monomers,isocyanate, and maleic anhydride

Wood could provide better service in some applications if it were harder and more dimensionally stable. In this study, wood–polymer composites (WPC) made with different chemical combinations were evaluated for dimensional stability, ability to exclude water vapor and liquid water, and hardness. Pine, maple, and oak solid wood were combined with different combinations of hexanediol diacrylate, hydroxyethyl methacrylate, hexamethylene diisocyanate, and maleic anhydride. Treatment slowed the rates of water vapor and liquid water absorption. Although the resultant dimensional stability was not permanent, the rate of swelling of WPC specimens was less than that of unmodified wood specimens. In addition, WPC were harder than unmodified wood. The chemical combination of hexanediol diacrylate, hydroxyethyl methacrylate, and hexamethylene diisocyanate greatly decreased wetting and penetration of water into the wood. This chemical combination also gave the hardest and most dimensionally stable WPC. In general, WPC prepared using hydroxyethyl methacrylate were harder than specimens made without hydroxyethyl methacrylate and excluded water and moisture more effectively. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 2493–2505, 1999     

PP-g-MAH增容改性木粉/PP复合材料的性能研究

以马来酸酐接枝聚丙烯 (PP-g-MAH) 为相容剂,聚丙烯 (PP) 为基体,通过熔融共混法制备了木粉/PP复合材料。研究了 PP-g-MAH 用量对复合材料力学性能及吸水性能的影响; 采用扫描电镜 (SEM) 观察了复合体系的冲击断面形貌。结果表明: 当 PP-g-MAH 的质量分数为 4%时,可以提高添加 35 份木粉复合材料体系的拉伸强度及弯曲强度,比未添加相容剂的分别提高了 49.4%和 16%,而缺口冲击强度仅下降了 9%。SEM 观察证实: PP-g-MAH 的加入有利于提高木粉与 PP 基体的界面相互作用。从吸水率来看,木粉/PP 复合材料的吸水率保持在 0.22% 以下,远低于纯木材。     

Abiotic and biotic degradation of post‐consumer polypropylene/ethylene vinyl acetate: Wood flour composites exposed to natural weathering

The effects of natural weathering on the visual appearance and chemical changes of wood plastic composite (WPC) formulations based on post‐consumer polypropylene/ethylene vinyl acetate (PP‐EVA) matrix were investigated. The WPC composition used was 70/30 (w/w) (recycled PP‐EVA/wood flour). Besides, the effectiveness of using coupling agent on adhesion of WPC and its influence in degradation were evaluated. Colorimetry, scanning electron microscopy, Fourier transform infrared spectroscopy, mechanical test, and biodegradation in simulated soil after natural weathering were used in this research. The results showed the samples with longer exposure time to natural weathering presented significant color change, increased in carbonyl index, and wood loss on weathered WPC surfaces. Weathered WPC exhibited decreased in mechanical properties, higher mass loss after biodegradation test when compared with no weathering WPC, reaching to 15.0% mass loss against 3.7%, respectively. Climatic conditions directly affect the characteristics of all composites, thus indicating a significant photo‐oxidation of the samples with a longer time of exposure to weathering, and this natural ageing has facilitated the WPC biodegradation . POLYM. COMPOS., 38:571–582, 2017. © 2015 Society of Plastics Engineers     

异氰酸酯对木塑力学性能与疏水性的影响

将木粉表面的羟基分别与异氟尔酮二异氰酸酯(IPDI)、甲苯二异氰酸酯(TDI)反应,再与聚乙烯(PE)通过挤出混合,挤出成型制备出了不同处理效果的木塑复合材料(WPC)。在不同种类和不同浓度的条件下,异氰酸酯改性木粉对木塑复合材料(WPC)的力学性能以及吸水率具有不同的影响。红外光谱(FTIR)和接触角测试表明,异氰酸酯成功接枝到木粉上。采用场发射扫描电子显微镜(FESEM)观察木粉与聚乙烯(PE)的相容性变化,通过微机控制电子万能试验机测试不同处理条件下的木塑复合材料力学性能,并参照GB/T 1462—2005计算了木塑吸水率。结果表明,在质量比为TDI∶木粉=5∶100条件下,木塑的力学性能和疏水效果最佳,拉伸强度达到27.8±0.7 MPa,浸入水中48 h吸水率达到0.45%。     

Wood‐thermoplastic composites manufactured using beetle‐killed spruce from Alaska

The primary objectives of the study were to characterize the critical properties of wood flour produced using highly deteriorated beetle‐killed spruce for wood‐plastic composite (WPC) production and evaluate important mechanical and physical properties of WPC extruded using an industry standard formulation. Chemical composition analysis indicated no significant differences in wood constituents between highly deteriorated and sound wood. Preliminary investigation with Fourier transform infrared spectroscopy (FTIR), however, indicated partial degradation or depolymerization of carbohydrate components in highly deteriorated wood compared to sound wood from green trees; effects of these changes could be seen in cell collapse and poor interaction between thermoplastic matrix and deteriorated wood fiber. Physical and mechanical properties of extruded WPCs manufactured from highly deteriorated material were comparable to WPC properties produced using pine wood flour that served as a control material. POLYM. ENG. SCI., 2009. © 2008 Society of Plastics Engineers     

Recycling of waste FRP and corn straw in wood plastic composite

Waste fiber reinforced polymer (FRP) combined with corn straw fiber was recycled and incorporated in wood plastic composite (WPC). The synergistic enhancement effect of glass fiber and corn straw fiber was investigated. The results show that there was a good physical interlocking structure among glass fiber of waste FRP, corn straw fiber and poly(vinyl chloride) (PVC) in WPC, which led to the enhancement of mechanical properties of WPC. With 30 phr (parts per hundreds of resin) waste FRP, the tensile strength and flexural strength of WPC were improved to 24 and 66 MPa, increased by 31% and 23% with respect to starting WPC. This study reveals that waste FRP and corn straw fiber can be good alternative for wood fiber in the production of WPC. POLYM. COMPOS., 38:2140–2145, 2017. © 2015 Society of Plastics Engineers