西南桤木木塑复合材料处理工艺的研究

以西南桤木作为试材,注入不饱和烯烃类单体。通过正交试验,分析了真空度、真空时间、浸注压力和加压时间4个因素对木材单体留存率的影响。并用光学显微镜和扫描电镜检测浸渍处理后高聚物在木材细胞壁内的分布情况。提出了较为理想的西南桤木木塑复合材处理工艺参数,能初步实现西南桤木木塑复合材的有效制备。     

木塑复合材料阻燃研究进展

对木塑复合材料(WPC)的阻燃研究进展进行了综合阐述,总结了近几年WPC用阻燃剂及阻燃处理方法的研究成果,并根据研究中存在的问题,着眼于提高阻燃剂的阻燃性及与WPC的相容性,展望了今后木塑复合材料在阻燃剂改性方面的研究方向。     

木塑复合材的工业应用

多年来,采用各种化学药剂处理以改善木材的物理性能。用乙烯基单体注入木材,然后在细胞腔和细胞壁中产生自由基增容聚合作用,有利于改善木材特殊的物理性能,这种方法已获得工业应用。工业上通常采用两种方法—辐射法和触媒—加热法制造木塑复合材。这种材料含有坚固的聚合物如商业牌号为Lucite或plexiglas,能够提高木材的硬度、耐磨性、抗压强度、体积稳定性等各项性能。由于对木塑复合材进行了全部综合处理,因此使用时的维护保养问题可控制到最低限度。生产木塑复合材的国家有美国、德国、英国、波兰、意大利、日本和新西兰等。木塑复合材拼花地板是主要的工业产品。其它产品还有射箭用的箭弓、弹子棒、高尔夫     

木塑复合材的工业化生产

木塑复合材(Wood Plastic Combina-tion缩写为WPC)就是将塑料单体,通过外加的能量,使之渗入木材内部,与木材产生聚合的一种新材料。它具有形状稳定性好,力学强度大,外表美观的特点。木塑复合材的研     

挤出木塑复合异型材模具的设计要点

<正>随着人们环保意识的加强,要求保护森林资源,减少利用新木材的呼声日趋高涨,回收利用低成本的废旧木材和塑料成为工业界和科学界普遍关注的问题。在这种情况下,木塑复合材料应运而生,人们也加大了对木塑复合材料(WPC)的研究和开发工作的力度,并     

再生木塑复合材料的研究进展

木塑复合材料（WPC）具有比单独的木质材料或塑料产品更优异的性质,是木材的理想代用品。从固体废弃物中分离出木材和塑料进行复合,不仅可以减缓废弃木材和塑料对城市环境的潜在污染,而且也适应了现代材料复合化发展的规律。文中论述了国内外学者在木塑复合材料方面所进行的研究情况及其应用前景和发展趋势。     

木塑复合材料老化性能研究进展

对木塑复合材料(WPC)在耐紫外线老化性能、耐潮湿及冰冻性能和耐真菌腐蚀性能方面的研究成果进行介绍,希望有助于正确评价和使用木塑复合材料,同时为新产品开发提供借鉴.WPC在紫外线作用下产生褪色现象,力学性能降低,而且喷水与紫外光的共同作用会加剧破坏程度;木粉含量高、颗粒大的WPC更易遭受真菌腐朽威胁,目前已研制出硼酸锌等多种专用防腐剂;WPC吸水速度慢,但绝大部分集中在表层,吸水与冻融循环都会降低力学性能.不同方式生产的WPC其性能有所差异.目前,对老化降解的机理问题仅进行了初步解释.     

利用废旧塑料制备木塑复合材料研究进展

利用废旧塑料与木质纤维制备木塑复合材料（WPC）是塑料资源重复利用、降低WPC制造成本的有效方式之一。简要介绍了废旧塑料的分类、来源以及危害,阐述了近年来利用废旧塑料制备WPC的概况,综述了利用物理和化学方法预处理木质纤维、原位增容改性等提高植物纤维/废旧塑料复合材料界面相容性的方法,并对利用废旧塑料制备WPC的前景进行了展望,以期提高废旧塑料基WPC的研发和实际应用。     

木塑共混复合材料

木塑共混复合材料(以下简称木塑材料)是近年来发展起来的一种新型材料,用木纤维或植物纤维填充、增强的改性热塑性材料,兼有木材和塑料的性能和特点,经挤出或压制成型为型材、板材或其他制品,可以替代木材和塑料,并且可以百分之百回收再生,是真正意义上的“绿色”工业制品,也是一种理想的木材替代材料。WPC对于扩大木材的应用领域、开拓植物纤维利用的新途径、减少我国木材的进口量等具有重要意义。木塑材料将两种不同材料的优点有机地结合在一起,它既可以像木材一样表面胶合、油漆,也可进行钉、钻、刨等,同时又可像热塑性塑料一样成型加…     

木塑复合材料中稻壳粉碱化处理条件的优化

采用单因素实验法和二次正交旋转组合试验设计对木塑复合材料(WPC)的稻壳粉的碱处理工艺进行了研究。建立了以木塑复合材料的弯曲强度为目标函数的二次多项数学模型。结果表明,所得回归方程显著,拟合情况良好。最佳的浸泡时间为15.2h,NaOH浓度为6%,在此条件下,木塑复合材料的弯曲强度达到17.35MPa。     

Static bending and toughness of wood polymer composites (yellow birch and basswood)

Wood polymer composites (WPC) were made from basswood and yellow birch using six cell lumen type polymer formulations. The study was designed to get insight into the influence of wood density and polymer formulation on certain WPC mechanical properties. Small specimens were tested for toughness, stiffness, hardness and bending strength using standard ASTM methods. Results showed that stronger and stiffer polymers produce tougher and stronger WPC, but the effect is small. Thus, there is a wide range of polymer properties which produce useful WPC properties. Study of the fracture surfaces using Scanning Electron Microscopy (SEM) showed that WPC made with different polymers fractured differently and polymer containing a coupling agent bonded to the cell wall. However the cell wall bonding had no noticeable influence on WPC mechanical properties.     

Effects of impregnation and heat treatment on the physical and mechanical properties of Scots pine (Pinus sylvestris) wood

Wood modification, of which thermal modification is one of the best-known methods, offers possible improvement in wood properties without imposing undue strain on the environment. This study investigates improvement of the properties of heat-treated solid wood. Scots pine (Pinus sylvestris) was modified in two stages: impregnation with modifiers followed by heat treatment at different temperatures. The impregnation was done with water glass, melamine, silicone, and tall oil. The heat treatment was performed at the temperatures of 180°C and 212°C for three hours. The modified samples were analyzed using performance indicators and scanning electron microscope micrographs. The mechanical and physical properties were determined with water absorption, swelling, bending strength, and impact strength tests. All the modifiers penetrated better into sapwood than hardwood; however, there were significant differences in the impregnation behavior of the modifiers. As regards the effect of heat treatment, generally the moisture properties were improved and mechanical strengths impaired with increasing treatment temperature. In contrast to previous studies, the bending strength increased after melamine impregnation and mild heat treatment. It is concluded that the properties of impregnated wood can be enhanced by moderate heat treatment.     

Preparation of acetylated wood meal and polypropylene composites II: mechanical properties and dimensional stability of the composites

Acetylated wood meals of Sugi (Cryptomeria japonica D.Don) wood were prepared by mechanochemical processing using a high-speed vibration rod mill. Weight percent gain (WPG) of the acetylated wood meals ranged from 7.0 to 35.5 %. Wood–plastic composites (WPCs) containing 50 % acetylated woods were produced by an injection molding technique. The polymer matrix used was polypropylene homopolymer. Maleic anhydride-grafted polypropylene (MAPP) was also used as a compatibilizing agent. The mechanical properties of WPCs in bending and tensile tests were independent of WPG of acetylated wood meals, and the test values for WPCs containing acetylated wood meals were lower than that of unmodified wood meal. The use of MAPP increased bending and tensile strength, but no effect on bending modulus was found. An increase in WPG significantly decreased water absorbability and thickness swelling of WPCs as measured by dimensional stability tests. These results demonstrated that mechanochemical processing is a promising technique for preparing WPC material with improved dimensional stability. The future challenge is to inhibit the decreases in mechanical properties of WPCs containing acetylated wood meals.     

改性辐射松木材物理力学性能研究

研究了辐射松树脂浸渍材与热空气热处理树脂浸渍材、热压热处理树脂浸渍材的物理力学性能,为后续辐射松改性处理和加工利用提供参考。结果表明:相对于未处理材,浸渍处理提高了木材的密度、尺寸稳定性、力学性能;相对于浸渍材,热处理可进一步提高尺寸稳定性,但一定程度降低了力学强度。     

红松幼龄材与成熟材力学性质的差异

本文研究了人工林和天然林红松幼龄材与成熟材力学性质的差异.结果显示,成熟材的所有力学性质均高于幼龄材.幼龄材与成熟材的抗弯弹性模量差异在人工林红松中达0.01水平显著,天然林红松也达到0.01水平显著;人工林红松抗弯强度和弦向横纹抗压强度差异达0.05水平显著.抗弯强度、顺纹抗压强度、横切面硬度和弦向横纹抗压强度4项指标的差异达0.05水平显著.     

人工林杉木木材力学性质对高温热处理条件变化的响应

以人工林杉木为试材,分别用空气和菜子油为介质,在温度为180,200和220 ℃对其分别热处理1,3和5 h,研究试材的抗弯强度(MOR)、抗弯弹性模量(MOE)、顺纹抗压强度、表面硬度对高温热处理条件变化的响应,同时对处理材的主要化学成分进行分析,用扫描电镜对处理材横切面微观结构进行观察.结果表明:人工林杉木试材的4种主要力学性质对不同条件热处理的响应程度不同.无论是空气热处理还是油热处理,试材的MOR,MOE,顺纹抗压强度与对照比有不同程度的降低,且随处理温度升高、时间延长,下降幅度增大,相比于时间,温度的影响更显著;180 ℃热处理1,3和5 h时,试材的MOR,MOE与对照比未发生明显变化(降幅在3%以内),而顺纹抗压强度则明显低于对照,两介质中降低幅度分别在3.29%～9.58%和3.89%～7.18%;200 ℃以上处理时,不同时间处理的3种主要力学性质不仅显著或极显著低于对照,且各性质问的差异也达显著或极显著水平;对硬度的测试结果表明:180 ℃热处理时,试件的径面硬度和弦面硬度均随时间的延长而增大;200 ℃热处理3 h时,试件的硬度达最大,与对照差异达显著水平;随后热处理试件的硬度开始降低,220 ℃热处理5 h后试件的硬度又明显低于对照.在隔氧的油介质中进行热处理,4种主要力学性质的变化程度低于空气介质处理材,当温度高于200 ℃时,两介质处理间的差异达显著水平.而热处理过程中木材主要化学组成与横切面微观结构变化的差异,反映了4种主要力学性质对不同条件热处理时表现出的响应差异.     

木塑复合板主要工艺对材料性能的影响

研究了木粉与聚丙烯为主要原料的复合材料的主要力学性能和尺寸稳定性.实验结果表明:热压时间对复合材料的力学性能有一定的影响,加压时间为9min,复合板的力学强度较优,吸水厚度膨胀率小;木塑配比对复合材料的力学性能有较大的影响,随着配比的增加,板性能呈现逐渐下降的趋势;配比对吸水厚度膨胀率影响明显,木粉的比例越高,吸水厚度膨胀率越高.     

Strength properties of thermally modified softwoods and its relation to polymeric structural wood constituents

Thermal modification at relatively high temperatures (ranging from 150 to 260 °C) is an effective method to improve the dimensional stability and resistance against fungal attack. This study was performed to investigate the impact of heat treatment on the mechanical properties of wood. An industrially-used two-stage heat treatment method under relative mild conditions (< 200 °C) was used to treat the boards. Heat treatment revealed a clear effect on the mechanical properties of softwood species. The tensile strength parallel to the grain showed a rather large decrease, whereas the compressive strength parallel to the fibre increased after heat treatment. The bending strength, which is a combination of the tensile stress, compressive stress and shear stress, was lower after heat treatment. This decrease was less than the decrease of only the tensile strength. The impact strength showed a rather large decrease after heat treatment. An increase of the modulus of elasticity during the bending test has been noticed after heat treatment. Changes and/or modifications of the main wood components appear to be involved in the effects of heat treatment on the mechanical properties. The possible effect of degradation and modification of hemicelluloses, degradation and/or crystallization of amorphous cellulose, and polycondensation reactions of lignin on the mechanical properties of heat treated wood have been discussed. The effect of natural defects, such as knots, resin pockets, abnormal slope of grain and reaction wood, on the strength properties of wood appeared to be affected by heat treatment. Nevertheless, heat treated timber shows potential for use in constructions, but it is important to carefully consider the stresses that occur in a construction and some practical consequences when heat treated timber is used.     

Treatments of southern pine with vinyl chloride and methyl methacrylate for radiation-produced wood-plastic combinations

Summary A method was developed for the impregnation of liquid vinyl chloride monomer into wood. Wood-plastic combinations (WPC) prepared from polymethyl methacrylate (PMMA), polyvinyl chloride (PVC), and polyvinyl chloride plasticized with diocylthalate (DOP+PVC) were found to offer improvements in selected physical properties of wood. The initial anti-swell efficiency (ASE) values of PMMA WPC and DOP+PVC WPC are very high, averaging approximately 87 and 82 percent respectively after 5 hours of soaking; whereas PVC WPC attained an average of only 53 percent. After prolonged soaking, the ASE values of all treated wood decreased considerably, indicating no permanent stability was achieved. In hardness, the PMMA WPC attained an average springwood-summerwood rating of 76, the DOP+PVC WPC and the PVC WPC a rating of 69 and 63, respectively; whereas the untreated wood achieved a rating of only 53.The authors gratefully acknowledge Dr.Oskar Klopfer of Ethyl Corp, Baton Rouge, La. for technical assistance.