木粉改性处理与木塑复合材料性能研究

通过对木粉进行改性处理,研究了不同改性剂及处理条件对高密度聚乙烯木塑复合材料物理力学性能的影响。结果表明:改性剂使木粉的玻璃化温度降低,纤维素的结晶度提高;随着改性剂用量的增加,木塑复合材料的弯曲强度、拉伸强度、弹性模量都有所提高,吸水率也略有升高;50℃下处理48h的木粉制备的木塑复合材料的物理力学性能较好;改性剂C处理的木塑复合材料综合性能较好。     

Role of paper sludge particle size and extrusion temperature on performance of paper sludge–thermoplastic polymer composites

The effect of paper sludge's particle size and extrusion temperature on the physical and mechanical properties of paper sludge–thermoplastic polymer composites was investigated. In the experiment three levels of particle sizes for the paper sludge and four extrusion temperatures were designed to examine the physical and mechanical properties of these composites. The ash contents of the paper sludge were about 73.7, 46.2, and 38.1% with particle sizes of below 0.15, 0.18–0.25, and 0.42–0.84 mm, respectively, which meant lower ash content and higher cellulose fiber content, in the larger particle size of paper sludge. As the particle size of the paper sludge decreased, the swelling thickness, water absorption, and tensile and flexural strengths of the composite improved; but the particle size of the paper sludge had no effect on its unnotched impact strength. With the increase of the extrusion temperature the thickness swelling and water absorption of the composites were slightly improved but not statistically different. A rise of the extrusion temperature generally had a positive effect on the tensile and flexural properties of the composite. The notched and unnotched impact strengths of the composite increased with the increase of the extrusion temperature from 190 to 230°C, but they decreased slightly at an extrusion temperature of 250°C. This low impact energy at an extrusion temperature of 250°C may be attributed to the excessively brittle fibers from thermal decomposition. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 2709–2718, 2001     

Effect of Coupling Agent Concentration,Fiber Content,and Size on Mechanical Properties of Wood/HDPE Composites

In this study, the influence of coupling agent concentration (0 and 3 wt%), wood fiber content (50, 60, 70, and 80 wt%), and size (40–60, 80–100, and 160–180 mesh) on the mechanical properties of wood/high-density-polyethylene (HDPE) composites (WPCs) was investigated. WPC samples were prepared with poplar wood-flour, HDPE, and polyethylene maleic anhydride copolymer (MAPE) as coupling agent. It was found that the tensile properties and the flexural properties of the composites were improved by the addition of 3 wt% MAPE, and the improved interfacial adhesion was well confirmed by SEM micrographs. It was also observed that the best mechanical properties of wood/HDPE composites can be reached with larger particle size in the range studied, while too-small particle size was adverse for the mechanical properties of wood/HDPE composites. Moreover, the tensile modulus, tensile strength, and flexural strength of WPCs decreased with the increase in fiber content from 50 to 80 wt%; the flexural modulus of WPCs increased with the increase in fiber content from 50 to 70 wt% and then decreased as the fiber content reached 80 wt%. The variances in property performance are helpful for the end-user to choose an appropriate coupling agent (MAPE) concentration, wood fiber content, and particle size based on performance needs and cost considerations.     

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。     

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。     

PLA/木薯厌氧渣复合材料的制备工艺

以木薯厌氧渣为填料,聚乳酸(PLA)为基体,采用模压成型制备了PLA/木薯厌氧渣复合材料,探究了木薯渣填充量、偶联剂添加量、机械球磨时间、温度、转速及模压温度、压力、时间等因素对复合材料力学性能的影响。结果表明,偶联剂占木薯渣质量的2%,木薯渣填充量为10%,球磨时间为30 min,球磨温度为60℃,球磨转速为300 r/min,模压时间为6 min,模压温度为190℃,模压压力为10 MPa时,复合材料的弯曲强度为63.108 MPa,拉伸强度为44.155 MPa,力学性能较好。以PLA与木薯厌氧渣为主要原料制备复合材料,既能有效降低复合材料的生产成本又能使复合材料保持较好的力学性能,避免了废弃木薯渣对环境的污染,且为实现生物质资源的高值化利用提供理论依据。     

Effects of A,B, and S components on fiber length distribution,mechanical, and impact properties of carbon fiber/ABS composites produced by different processing methods

Carbon fiber/ABS composites with different acrylonitrile, butadiene, and styrene components were produced via extrusion/injection and long fiber thermoplastic (LFT)/injection molding processes, respectively. The effect of the components on fiber length distribution, tensile, flexural, impact, and dynamic mechanical properties of the composites was investigated. The properties of carbon fiber/ABS composites produced using 12 mm-long LFT pellets were markedly higher than those produced using extruded pellets made with 12 mm-long chopped carbon fibers. Uses of LFT pellets were preferable to enhancing the mechanical properties of carbon fiber/ABS composites. The tensile, flexural, and dynamic mechanical properties were increased in order of ABS750sw > ABS720 ≥ ABS780 > ABS740, whereas the impact strength was increased in order of ABS740 > ABS780 > ABS720 ≈ ABS750sw. Less carbon fiber damages and less carbon fiber length degradation upon LFT processing resulted in longer fiber length distribution and higher fiber aspect ratio in the composites with LFT pellets, indicating a beneficial reinforcing effect, which was responsible for the increased mechanical properties of ABS composites, particularly with ABS750sw. The results were agreed with each other, significantly depending on the A, B, and S components, being supported by fiber length distribution, fiber aspect ratio, and fracture surfaces.     

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     

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%。     

聚丙烯/木粉/纳米凹凸棒土复合材料性能研究

采用双螺杆挤出机制备了一系列聚丙烯(PP)/木粉/纳米凹凸棒土(AT)木塑复合材料(WPC.研究了AT用量对复合材料力学性能、热性能、加工性能的影响.结果表明,随着AT用量的增加,复合材料拉伸强度逐渐增加、冲击强度逐渐减小,硬度先增加后减小,AT用量为5份时复合材料硬度最大;复合材料维卡软化点不断提高;熔体流动速率(M...     

Effects of fungal decay on properties of mechanical,chemical, and water absorption of wood plastic composites

This study investigated the associations between wood species and fungal resistance, as well as the effects of fungal decay on the properties of mechanical, chemical, and water absorption of wood polypropylene composites (WPCs) filled with white poplar, moso-bamboo, Chinese fir, Ramin, white pine, and rubber wood. Experimental results on weight losses and surface morphology both showed that fungal resistance of WPCs varied significantly with wood fiber species. Chinese fir and rubber wood filled composites separately presented the most and least durability against Coriolus versicolor (white rot) and Poria placenta (brown rot). In addition, fungal decay produced great differences in the properties of mechanical, chemical, and water absorptions between non-decayed and decayed composites. The decayed composites showed lower MOR, tensile strength, and impact strength, as well as higher MOE and water absorptions compared with non-decayed samples. These findings suggest that fungal decay could bring out dramatic influences on various properties of WPCs.     

NaOH/尿素冷冻活化木材纤维的工艺研究

利用NaOH/尿素混合水溶液在冷冻条件下对木材纤维进行活化处理,通过无胶胶合压制纤维板的力学性能测试、傅里叶变换红外光谱以及X射线衍射分析表征了木材纤维的冷冻活化效果。结果表明：冷冻条件下NaOH/尿素的混合水溶液对木材纤维具有一定的活化效果,优选的活化工艺为NaOH和尿素的总质量（NaOH与尿素质量比为7：12）与木材纤维质量比为1：12,冷冻温度-15℃,冷冻时间1.0 h,木材纤维含水率20%。木材纤维经NaOH/尿素混合水溶液冷冻活化后,所得无胶胶合板材的静曲强度和内结合强度分别由未处理的32.16和0.29 MPa提高至45.53和1.21 MPa,吸水率和厚度膨胀率由未处理的53.95%和22.57%降低至43.62%和10.34%。傅里叶变换红外光谱和X射线衍射表征发现,NaOH/尿素混合水溶液的冷冻活化破坏了木材纤维中纤维素的氢键结构,促使了纤维素I型晶格扩张,产生了新的结晶变体,使分子缔合程度变小,木材纤维表面的羟基活性增强。     

Characterization of wood-filled thermoplastic polyurethanes for the injection molding process

Fiber fillings of wood plastic composites (WPC) are almost exclusively limited to standard plastics such as polyethylene and polypropylene. At the Kunststofftechnik Paderborn of the University of Paderborn the wood fiber filling of engineering plastics is being promoted. WPC with different fiber types and fiber contents based on two thermoplastic polyurethanes (TPU) were compounded and subsequently characterized. We found that the physicochemical properties of the materials differ from standard plastic-based WPC. Wood filling with increasing fiber content did not immediately correlate with an increase in density. A decrease in density and swelling of the compound was detected with reaching a critical fiber content. Our compounds showed an increased water absorption at high-fiber contents over time, which can be described logarithmically. The observed viscosity curves obey the Ostwald and de Waele power law, but an increased viscosity at increased fiber content was not apparent for both TPU matrices.     

Water uptake and mechanical characteristics of natural filler–polypropylene composites

Water uptake characteristics and some mechanical properties of polypropylene composites containing three types of natural fillers, purified α‐cellulose, wastepaper fibers, and wood flour were studied. The fiber contents were 15, 25, and 35% by weight. Two percent maleic anhydride polypropylene (MAPP) was also added to the mix, as the compatibilizer agent. Mixing process was performed in a Brabender Plasticorder until a constant torque was reached. Composites made out of these combinations were then pressed in a laboratory press and ASTM standard test specimens were cut out of the sheets. Water absorption and tensile tests were performed on these specimens. The results showed a significant difference between the various filler types regarding water uptake. Water uptake also increased by the increase in filler content. Tensile strength and elongation at break in composites declined when compared with pure polypropylene, but their modulus of elasticity increased. Among the three types of fillers, no significant discrepancies were observed in terms of improving mechanical properties in composites. Filler content increase had no drastic effect regarding strength improvement. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 941–946, 2003     

Biopolyamide hybrid composites for high performance applications

This study focuses on the performance characteristics of wood/short carbon fiber hybrid biopolyamide11 (PA11) composites. The composites were produced by melt‐compounding of the fibers with the polyamide via extrusion and injection molding. The results showed that mechanical properties, such as tensile and flexural strength and modulus of the wood fiber composites were significantly higher than the PA11 and hybridization with carbon fiber further enhanced the performance properties, as well as the thermal resistance of the composites. Compared to wood fiber composites (30% wood fiber), hybridization with carbon fiber (10% wood fiber and 20% carbon fiber) increased the tensile and flexural modulus by 168% and 142%, respectively. Izod impact strength of the hybrid composites exhibited a good improvement compared to wood fiber composites. Thermal properties and resistance to water absorption of the composites were improved by hybridization with carbon fiber. In overall, the study indicated that the developed hybrid composites are promising candidates for high performance applications, where high stiffness and thermal resistance are required. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43595.     

A comparative study on the effects of material blending method on the physico‐mechanical properties of WPCs made from MDF dust

The present study was carried out to investigate the effect of material ‐ blending method and filler content on the physical and mechanical properties of medium density fiberboard (MDF) dust/PP composites. In the sample tests preparation, 40, 50, and 60 wt % of MDF dust were used as lignocellulosic material. Test samples were made to measure the influence of material ‐ blending method and MDF dust content on water absorption (WA), thickness swelling (TS), modulus of elasticity (MOE), modulus of rupture (MOR), tensile strength, tensile modulus, and withdrawal strengths of fasteners. The mechanical properties of the test panels significantly decreased with increasing MDF dust contents due to the reduction of interface bond between the fiber and polymer matrix. The WA and TS values also increased by increasing the amount of MDF dust. So with the increase in the MDF dust content, there are more water residence (high hydroxyl groups (? OH) of cellulose and hemicelluloses) sites, thus more water is absorbed, so it can reduce mechanical strength. Furthermore, the results indicated that the physical and mechanical properties of samples made with melt ‐ blend method were more acceptable than those of dry ‐ blend method. Field emission scanning electron microscopy micrographs also showed that the polymer and the filler phase mixed better in the melt ‐ blend method. On the basis of the findings of this research, it appears evident that certain amount of MDF dust material with suitable material ‐ blending method can be used in manufacturing of wood–plastic composites for providing good physical and mechanical properties. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40513.     

Preparation and characterization of LDPE and PP—Wood fiber composites

Natural fiber reinforced composites is an emerging area in polymer science. These natural fibers are low cost fibers with low density and high specific properties. These are biodegradable and nonabrasive. The natural fiber composites offer specific properties comparable to those of conventional fiber composites. However, in development of these composites, the incompatibility of the fibers and poor resistance to moisture often reduce the potential of natural fibers, and these draw backs become critical issue. Wood‐plastic composites (WPC) are a relatively new class of materials and one of the fastest growing sectors in the wood composites industry. Composites of wood in a thermoplastic matrix (wood–plastic composites) are considered a low maintenance solution to using wood in outdoor applications. WPCs are normally made from a mixture of wood fiber, thermoplastic, and small amounts of process and property modifiers through an extrusion process. In this study, Wood–plastic composites (WPC) are produce by adding a maleic anhydride modified low density polyethylene coupling agent to improve interfacial adhesion between the wood fiber and the plastic. Mixing is done with twin screw extruder. Subsequently, tensile strength, the modulus of elasticity, % elongation, hardness, Izod impact strength, melt flow index (MFI), and heat deflection temperature (HDT) are determined. Thermal transition temperatures and microstructure are determined with DSC and SEM, respectively. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Physico-mechanical studies of wood fiber reinforced composites

Wood polypropylene composites (WPC) of different compositions (30, 40, and 50%) have been prepared using maleic anhydride–polypropylene copolymer of different percentage (5 and 10% relative to their wood fiber content). Tensile, flexural, fracture toughness, and impact test of the prepared WPC were carried out. From the results, it is observed that the hard wood fiber–polypropylene composites, by using maleated polypropylene (MAH-PP), show comparatively better performance to soft wood fiber–polypropylene composites. Tensile strength and charpy impact strength have been increased to a maximum of 50 and 20%, respectively. The damping index has been decreased by 60% when 10% of MAH-PP has been used. Water absorption and scanning electron microscopy of the composites are also investigated.     

有机/无机填料混杂增强木塑复合材料制备与性能

针对木塑复合材料力学性能较低和湿热环境下易变形的不足,研究了矿物填料和木粉混杂增强高密度聚乙烯(HDPE)木塑复合材料的力学性能和湿热特性,初步分析了矿物填料微观结构和增强作用的关联关系。结果表明,添加矿物填料对木塑复合材料的弯曲、拉伸和冲击性能有不同程度的改善作用,对模量的提高尤为明显。具有丝束或丝絮状纤维结构的海泡石、硅铝酸纤维和硅灰石对木塑复合材料的增强作用要低于具有长条状纤维结构的水镁石纤维,纤维缠结导致的分散困难可能是其增强作用差的主要原因。海泡石对耐热温度和洛氏硬度的提高作用要优于其它矿物填料,添加了25份海泡石纤维的木塑复合材料的硬度和耐热温度分别提高57. 7%和26%。     

棉秆塑木复合材料的制备及性能研究

以棉秆粉和回收聚乙烯为原料、钛酸酯为偶联剂,采用热压法制备了棉秆塑木复合材料,利用正交试验法探讨了棉秆粉含量、热压温度和保温时间对塑木复合材料性能的影响,并通过物理力学性能测试单独考察了棉秆粉含量对塑木复合材料性能的影响。正交试验法的结果表明:棉秆粉含量对复合材料的弯曲强度、弹性模量和吸水率影响最大,热压温度和保温时间对复合材料的弯曲强度和弹性模量影响较大,对吸水率影响不大;当棉秆粉含量为40%、热压温度为160℃、保温时间为10 min时,塑木复合材料具有最优的综合性能。物理力学性能测试结果表明:复合材料的弯曲强度和弹性模量随棉秆粉含量的增加均呈现先增大后减小的趋势,在棉秆粉含量为40%时均达到最大值;吸水率随棉秆粉含量的增加而增大。