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1.
木塑复合材料的界面相容性是决定其性能的关键因素,通过添加偶联剂的方法能够改善其界面相容性,从而提高其性能。通过测定毛白杨木粉/聚丙烯复合材料的物理力学性能来研究木粉含量和偶联剂添加量对木塑复合材料物理力学性能的影响,为进一步研究木塑复合材料的界面相容性提供理论依据。研究结果表明:随着木粉含量的增加,复合材料的物理力学性能下降,并且在高木粉含量阶段影响显著;高木粉含量复合材料的性能较差,添加MAPP能显著改善其物理力学性能。 相似文献
2.
In order to improve wood properties of triploid clones of Populus tomentosa, urea-formaldehyde (UF) resin was compounded with nano-SiO2, coupling agents and flame retardants in different ways to prepare five kinds of modifiers. The poplar wood samples were
impregnated with the modifiers and heated to prepare UF-SiO2-wood composites. The antiswelling efficiency, resistance of water absorption, oxygen index and hardness of the composites
were measured. Results show that all of the modifiers reduced water absorption of poplar wood and enhanced flame resistance
and hardness. Nano-SiO2 showed a marked effect in improving the hardness of wood. In addition, all of the modifiers, except UF-C-SiO2-polymer, improved the dimensional stability of poplar wood. The UF resin and nano-SiO2 compound improved general properties of poplar wood.
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Translated from Journal of Beijing Forestry University, 2006, 28(2): 123–128 [译自: 北京林业大学学报] 相似文献
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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. 相似文献
5.
In order to reduce the density of wood-based composites without causing a deterioration of their mechanical properties, we
studied the process of manufacturing wood-based composites. A combination of polymer foaming technology and flat hot-pressing
technology was used. The microscopic structure of the various wood-based composites was analyzed with a scanning electron
microscope (SEM). Modulus of rupture (MOR), modulus of elasticity (MOE), impact strength, and thickness expansion rate of water sorption (TS) were all measured. The results showed that fibers loosely interweave, and fibers had been connected by micropore. They also
showed that spaces between fibers had big micropore structure. MOR, MOE and impact strength were the highest among three levels of ratio. When the total content of resin and foaming agent were
20% by weight, TS was higher. A hot-pressing temperature of 120°C was optimal. At the low temperatures of 80°C, the foaming process was uncompleted.
At a higher temperature, micropores burst at a certain pressure. Based on the variance analysis and maximum difference analysis,
a significance test shows that the optimum conditions for the total content of resin and foaming agent is 20% by weight, with
a hot pressing temperature of 120°C for 15 min. Under these conditions, the properties of wood-based foaming composites all
achieved the industry standard.
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Translated from Journal of Beijing Forestry University, 2007, 29(3): 154–158 [译自: 北京林业大学学报] 相似文献
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Marc H. Schneider Svetlana Vasic Stig Lande Jonathan G. Phillips 《Wood Science and Technology》2003,37(3-4):165-176
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. 相似文献
8.
In this paper, we discuss the effects of a nanometer silicon dioxide (nano-SiO2) coupling agent, dispersal methods and the amount of nano-SiO2/urea formaldehyde resin. The results of our study indicate that when nano-SiO2, using KH-550 silane as a coupling agent, was added to UF resin by discontinuous ultrasonic vibration, its properties improved
effectively. When the content of nano-SiO2 was below 1.5%, the amount of free formaldehyde decreased, and the viscosity and bonding strength of resin increased with
an increase in the added nano-SiO2, which did not prolong the curing time. The performance indices of plywood, particleboard and medium density fiberboard (MDF),
hot-pressed by nano-SiO2 (1%)/UF resin (F/U molar ratio=1.2), exceeded the requirements of the National Standard. Their free
formaldehyde emission reached E1 grade. Finally, we analyzed the mechanism of the strengthening effects of nano-SiO2 on UF resin by means of infrared spectrum analysis and X-ray photoelectronic spectrum (XPS).
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Translated from Scientia Silvae Sinicae, 2005, 41(2) [译自: 林业科学, 2005, 41(2)] 相似文献
9.
木塑复合材料力学性能影响因子研究进展 总被引：1，自引：1，他引：0
木塑复合材料（WPC）的力学性能在很大程度上决定其应用领域,其影响因子有木质增强填料（种类、含量、形态及预处理）、热塑性塑料基体（类型及预处理）、偶联剂、含水率、成型方法及环境因素等。文中综述了上述影响因子对WPC力学性能影响的一般规律,分析了研究中存在的主要问题,并对其未来研究趋势进行了展望。 相似文献
10.
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 cryoractured 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. 相似文献
11.
Wenjie Dang Yongming Song Qingwen Wang Weihong Wang 《Frontiers of Forestry in China》2008,3(2):243-247
To improve the interfacial compatibility between wood fibers and polypropylene and the toughness of wood-fiber/polypropylene
composites, maleic anhydride grafted polypropylene (PP-g-MAH) and maleic anhydride grafted styrene-ethylene-butadiene-styrene
copolymers (SEBS-g-MAH) were used as modifiers. Mechanical properties of wood-fiber/polypropylene (WF/PP) composites were
improved when PP-g-MAH or SEBS-g-MAH was added. When either of these copolymers was added, the composites had better interfacial
compatibility than the unmodified composite. This was verified by scanning electron microscope (SEM) observations and dynamic
mechanical analysis (DMA). The mechanical properties of the composites were significantly improved because of the good interfacial
bonding between wood fibers and polypropylene when PP-g-MAH and SEBS-g-MAH were added.
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Translated from Journal of Beijing Forestry University, 2007, 29(2): 133–137 [译自: 北京林业大学学报] 相似文献
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Sébastien Migneault Ahmed Koubaa Fouad Erchiqui Abdelkader Chaala Karl Englund Michael P. Wolcott 《Wood Science and Technology》2011,45(3):521-532
Wood–plastic composites (WPC) were produced with white birch pulp fibers of different aspect ratios (length-to-diameter),
high-density polyethylene, and using two common processes: extrusion or injection molding. Three additive levels were also
used: no additive, compatibility agent, and process lubricant. Fiber size was measured with an optical fiber quality analyzer.
Tensile properties of WPC were measured and modeled as a function of fiber aspect ratio. Models were fitted to experimental
values using the minimum sum of squared error method. A shift from the oriented fiber case (injection molding) to the randomly
oriented fiber case (extrusion) was achieved using a fiber orientation factor. Fiber/matrix stress transfer increased with
increasing fiber aspect ratio. Stress transfer was reduced with the use of process lubricant. Unexpectedly, the compatibility
agent had the same effect. Fiber strength and stiffness contributions to the composite were lower than those of intrinsic
fiber properties. 相似文献
13.
Khandkar- Siddikur Rahman Md Nazrul Islam Sourav Bagchi Ratul Nabila Hasan Dana Saleh Md. Musa Md. Obaidullah Hannan 《Journal of Wood Science》2018,64(3):279-286
This paper presents the effects of particle size and mixing ratio on the properties including physical, mechanical, and decay resistance of wood plastic composites (WPCs). In addition, it also presents the effects of immersion temperatures on water absorption (WA) and thickness swelling (TS) of the WPCs. WPCs with a thickness of 6 mm were fabricated from Albizia richardiana King & Prain wood particles and recycled polyethylene terephthalate (PET) by the flat-press method. To prepare the WPCs, two different wood particle sizes (0.5–1.0 and 1.01–2.0 mm) were used along with four different mixing ratios (w/w). Subsequently, the physical properties include density, moisture content, WA, and TS, and mechanical properties include modulus of elasticity (MOE) and modulus of rupture (MOR) of the produced WPCs was evaluated. Furthermore, decay resistance was evaluated by the weight loss percentage method. Moreover, the effects of immersion temperatures on WA and TS of WPCs after 24 h of immersion in water at three different temperatures, i.e., 25, 50, and 75 °C were investigated. Results showed that the wood particle size had impact on WPC’s density (only 6% decreased with the increase of particle size); however, the density decreased by 29% when the wood particle content increased from 40 to 70%. The WA and TS gradually increased with the increase of particle content and decrease of particle size. In addition, WA and TS increased proportionately with increasing immersion temperature from 25 to 75 °C. Furthermore, the highest MOE (2570 N/mm2) was found for the WPCs fabricated from large wood particles having the ration of 50:50 (wood particle:PET). For decay resistance, WPCs consisted of larger particles and higher PET content showed greater resistance against decay. Therefore, it is comprehensible that fabrication of the WPCs from 50% large particles and 50% PET is technically feasible and further improvement of WPC performance like enhancement of MOE and reduction of density using coupling agent and agricultural waste fibers, respectively, in the WPC formulation is recommended. 相似文献
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木塑复合材料(WPC)是一种兼具有木材和塑料双重优点的新型复合材料,在建筑、家具、装饰、运输和汽车内衬等领域显示出独特的优势并得到了迅速发展。为了进一步降低成本和增强木质感,商业化WPC产品的木质纤维填充量在40%～60%,甚至超过70%。这种高的木质纤维填充量造成了WPC挤出加工困难,主要表现为不稳定流动及表面撕裂等现象的出现,由此导致产品质量差,加工效率低。目前,人们对这种高填充体系下WPC熔体的流变行为尚不完全理解,更是缺乏系统的理论基础。高填充体系下WPC熔体中木质纤维材料与木质纤维材料之间、木质纤维材料与聚合物基体之间相互作用增强,其中木质纤维材料(种类、尺寸、填充量)、聚合物基体的分子质量和分子质量分布、润滑剂、偶联剂都是该复杂体系流变行为的重要影响因素。本文对高木质纤维填充体系下WPC的流变行为研究进行系统回顾,以期为WPC的配方设计、工艺控制、加工设备升级和模具制造提供一定的理论基础和科学依据。 相似文献
17.
This paper studied root biomass and underground carbon (C) and nitrogen (N) storage of a more than 200-year-old primitive
Korean pine and broad-leaved forest and its two 20-and 80-year-old secondary Populus davidiana and Betula platyphylla forests in Changbai Mountain, northeast China. The results showed that with forest succession, the root biomass of 20-year-old,
80-year-old, and primitive forests was 2.437, 2.742, and 4.114 kg/m2, respectively. The root C storage was 1.113, 1.323, and 2.023 kg/m2, soil C storage was 11.911, 11.943, and 12.587 kg/m2, and underground C storage was 13.024, 13.266, and 14.610 kg/m2, respectively, while the root N storage was 0.035, 0.032, and 0.038 kg/m2, soil N storage was 1.208, 1.222, and 0.915 kg/m2, and underground N storage was 1.243, 1.254, and 0.955 kg/m2, respectively, which indicated that along with forest succession, the forest underground became a potential “carbon sink,”
whereas underground N storage did not change obviously.
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Translated from Chinese Journal of Applied Ecology, 2005, 16(7): 1,195–1,199 [译自: 应用生态学报, 2005, 16(7): 1,195–1,199] 相似文献
18.
Feasibility of supercritical carbon dioxide as a carrier solvent for preservative treatment of wood-based composites 总被引：4，自引：0，他引：4
Supercritical carbon dioxide (SC-CO2) was tested for its potential as a carrier solvent for preservative treatment of solid wood and wood-based composites. A
preliminary trial showed that the treatability of solid wood varied with its original permeability and that the SC-CO2 treatment was not promising for refractory timber species such a Larix leptolepis Gordon. In contrast, 3-iodo-2-propynyl butylcarbamate (IPBC)/SC-CO2 treatment resulted in enhanced decay resistance without any detrimental physical or cosmetic damage in all structural-use
wood-based composites tested: medium density fiberboard, hardwood plywood, softwood plywood, particleboard, and oriented strand
board (OSB). Further trials under various treatment conditions [25°C/7.85 MPa (80 kgf/cm2), 35°C/7.85 MPa, 45°C/7.85 MPa, 35°C/11.77 MPa (120 kgf/cm2), and 45°C/11.77 MPa] indicated that although small changes in the weight and thickness of the treated materials were noted
the strength properties were not adversely affected, except for a few cases of softwood plywood and oriented strand board.
The results of this study clearly indicated that the treatment condition allowed SC-CO2 to transport IPBC into wood-based composites, and the optimum treatment condition seemed to vary with the type of wood-based
composite.
Received: October 24, 2001 / Accepted: February 15, 2002
Part of this work was presented at the 51st Annual Meeting of the Japan Wood Research Society, Tokyo, April 2001; and the
32nd Annual Meeting of the International Research Group on Wood Preservation, Nara, May 2001
Correspondence to:M. Muin 相似文献
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Xingliang Liu Qinyan Ma Dongsheng Yang Zuoming Shi Yiming Su Shiqiang Zhou Shirong Liu Yupo Yang 《Frontiers of Forestry in China》2006,1(4):379-386
This study investigated root biomass and productivity in dominant populations in western Sichuan, China. A total of 4 plots
(Picea balfouriana plantation for 22 age in Maerkang, 9 trees, mean DBH of population for 10.4 cm and height for 10.5 m; Larix maxteriana plantation for 22 age in Wolong, 9 trees, mean DBH of population for 17.0 cm and height for 13.8 m; Abies fabri plantation for 35 age in Ebian, 18 trees, mean DBH of population for 14.1 cm and height for 11.9 m; Larix kaempferi plantation for 23 age in Miyaluo, 8 trees, mean DBH of population for 17.4 cm and height for 14.5 m; a 20 m×25 m plot located
on each of the 4 types in western Sichuan, China) were randomly selected and excavated to a depth of 60 cm for each of the
4 plantation types. To estimate the root biomass of an individual tree using D
2
H, an exponential model was selected with the highest coefficient ranging from 0.94 to 0.99. The total root biomass per hm2 varied among plantation population types following the order: L. kaempferi (37.832 t/hm2) > A. fabri (24.907 t/hm2) > L. maxteriana (18.320 t/hm2) > P. balfouriana (15.982 t/hm2). The biomass fractions of a given root size class compared to the total root biomass differed among plantation population
types. For all 4 studied plantation types, the majority of the roots were distributed in the top 40 cm of soil, e.g., 97.88%
for P. balfouriana population, 96.78% for L. maxteriana, 95.65% for A. fabri, and 99.72 for L. kaempferi population. The root biomass fractions distributed in the top 20 cm of soil were 77.13% for P. balfouriana, 77.13% for L. maxteriana, 65.02% for A. fabri and 80.66% for L. kaempferi, respectively. The root allocation in the 0–20, 20–40, and 40–60 cm soil layers gave ratios of 34:12:1 for P. balfouriana, 24:6:1 for L. maxteriana, 15:7:1 for A. fabri, and 64:4:1 for L. kaempferi populations. The root biomass density of dominant plantation population was 10.782 t/(hm2·m) for P. balfouriana, 8.230 t/hm2·m) for L. maxteriana, 24.546 t/(hm2·m) for A. fabri, and 13.211 t/(hm2·m) for L. kaempferi population, respectively. The root biomass productivity was found to be 0.57 t/(hm2·year) for P. balfouriana, 0.83 t/(hm2·year) for L. maxteriana, 0.71 t/(hm2·year) for A. fabri and 1.64 t/(hm2·year) for L. kaempferi population, respectively.
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Translated from Acta Ecologica Sinica, 2006, 26(2): 542–551 [译自: 生态学报, 2006, 26(2): 542–551] 相似文献
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The relative effects of irradiance and soil water on alley-cropped herbage are poorly understood. Our objective was to determine
effects of irrigation on herbage productivity when tall fescue [Lolium arundinaceum (Schreb.) Darbysh.] was grown in two sites, a meadow and a loblolly pine (Pinus taeda L.) alley (620 trees ha−1), near Booneville, Arkansas. Three tall fescue entries were space planted in the meadow and pine alley with or without irrigation.
Herbage mass and nutritive value were determined at 8-week intervals for 2 years. Mean daily PAR was 33.9 (2004) and 37.5 mol m−2 d−1 (2005) in the meadow, while the pine alley received 5.6 mol m−2 d−1 (17% of the meadow) in 2004 and 4.3 mol m−2 d−1 (11% of meadow) in 2005. Effect of tall fescue entry tended to be small relative to site and irrigation. Irrigation compensated
for evapotranspiration in the meadow, but not in the pine alley when summer rainfall was about normal (2004) or low (2005).
Nevertheless, site (PAR) had a greater effect on herbage specific leaf weight, leaf elongation rate, tillers plant−1, mass tiller−1, and total nonstructural carbohydrate concentration than soil water. Irrigation might have had greater impact on herbage
productivity if more water had been applied or if canopy cover had been less extreme. Silvicultural practices should be imposed
to improve penetration of solar irradiance to the alley crop. 相似文献