Reinforcement of fiberboard containing lingo-cellulose nanofiber made from wood fibers

Wood-based materials are fabricated with adhesives composed of various materials derived from fossil fuels. It is difficult to identify replacements for these chemical adhesives. This study explored nanofiber technologies as an alternative to these adhesives. In this study, we focused on reinforcement effects of lingo-cellulose nanofiber (LCNF) on fiberboards made from softwood and hardwood fiber. We discuss the density effects of reinforcement with LCNF because the density of medium-density fiberboard (MDF), which is widely used for construction, is standardized at about 0.60–0.80 g/cm³. Fiberboards were manufactured with three densities (0.60, 0.75, and 1.00 g/cm³). For softwood fiberboards, the bending properties for LCNF-mixed boards were higher than those for the control fiberboards at all densities. In this paper, control fiberboard means fiberboard with fiber only. For hardwood fiberboards, the bending properties for LCNF-mixed fiberboard for 1.00 g/cm³-density board were higher than those for the control fiberboard. For internal bond strength (IB), the IB for LCNF-mixed fiberboard was higher than that for the control fiberboard. The thickness swelling (TS) and weight change (WC) with water absorption for fiberboards containing LCNF were lower than those for control fiberboards. As a conclusion, physical and mechanical properties of the resulting fiberboards were significantly improved with the addition of LCNF, especially for softwood fiberboards, due to close binding between LCNF and wood fibers.     

Binding effect of cellulose nanofibers in wood flour board

Wood-based materials are extensively used for residual construction worldwide, especially in Japan. Most wood-based materials are fabricated using adhesives, some of which are not environmentally friendly. As an alternative to chemical adhesives, we explored this issue using nanofiber technology, especially the use of cellulose nanofibers (CNF), as reinforcement in wood flour (WF) board to replace chemical adhesives. We found that CNF could be easily made by pulverization in a ball mill. The physical and mechanical properties of WF board were improved by the three-dimensional binding effects of the CNF.     

Improvement of dimensional stability and weatherability of composite board made from water-vapor-exploded wood elements by liquefied wood resin impregnation

High-density and high-resin-content boards were produced by phenolic resin impregnation into board materials prepared by the water-vapor-explosion process (WVE) to develop high-durability wood composite boards for exterior use. Wet-dry cyclic tests and accelerated weathering tests were conducted, and the fundamental properties were determined to examine the effect of resin impregnation on board qualities. Bending and internal bond strength of resin-impregnated boards (I-board) satisfied the criterion for 18-type particleboard described in JIS A 5908. Thickness swelling (TS) after 24-h water immersion was approximately 2%. Resin impregnation improved the dimensional stability of the boards. In wet—dry cyclic testing, TS of I-board was the same as that of plywood. The retention ratio of modulus of rupture of I-board was large; thus, I-board had high bond durability. Color change of I-board was less than that of ordinary particleboard after a 500-h accelerated weathering test. I-Board had lower surface roughness than boards produced by a spray application method (S-board) and higher water repellency, although the difference in resin contents of the face layer was small. Thus, it is suggested that the surface properties and weatherability of I-board were improved by impregnation of phenolic resin. High-density and resin-impregnated boards made from the WVE elements are expected to withstand actual exterior use. Part of this report was presented at the 54th Annual Meeting of the Japan Wood Research Society, Sapporo, August 2004     

硬质纤维板压制混凝土模板的研究

探讨用硬质纤维板制造混凝土模板的可行性。用正交试验法研究浸胶时间、浸胶后干燥时间、树脂与水的比率、热压压力、时间和温度对硬质纤维板混凝土模板性能的综合影响；进而进行生产性试验，以验证优化工艺的可靠性。     

杨木水泥刨花板工艺的研究

对杨木水泥刨花板的物理力学性能与主要工艺参数——密度、木灰比、水灰比、添加剂及添加量的关系作了研究。结果表明,密度(D)对板材性能影响最大,木灰比(W/C)次之,水灰比(W_1/C)最小;板材的主要性能如MOR、MOE、IB同密度、木灰比、水灰比的关系,可用方程Y=a_0+a_1D+a_2(W/C)+a_3(W/C)~2+a_4(W_1/C)+a_5(W_1/C)~2表示;在各种添加剂中,以氯化钙的效果最好。     

Technological properties of glulam beams made from hydrothermally treated poplar wood

In this research, technological properties of glulam beams made from hydrothermally treated poplar (Populus deltoides) wood were investigated. Poplar wood blocks with dimensions of 6 (r)?×?10 (t)?×?73 (l)?cm³ were cut and hydrothermally treated in a stainless steel reactor at temperatures of 140 and 160°C for a holding time of 30?min. The treated wood blocks were initially air seasoned and then they were dried in a semi-pilot scale vacuum dryer to achieve moisture content (MC) of 12%. Conditioning of the treated and the untreated wood blocks was done prior to adhesive bonding. Afterwards the glulam beams (4 ply) were manufactured using polyurethane. In order to evaluate the physico-mechanical properties of the beams, density, equilibrium moisture content, water repellent effect (WRE), anti-swelling effect (ASE), mass loss (ML), wettability as well as surface roughness due to the hydrothermal treatment were determined in the treated wood and delamination, bond shear strength, tensile strength, MC and moisture-induced stresses as well as strains in cross-section of the beams were determined in the glulam beams. The results revealed that density, ML, ASE, WRE, modulus of elasticity, modulus of rupture and delamination were increasing and the others were decreased due to the hydrothermal treatment.     

Effect of adding steam-exploded wood flour to thermoplastic polymer/wood composite

The effect of steam-exploded wood flour (SE) added to wood flour/plastic composite was examined using SE from beech, Japanese cedar, and red meranti and three kinds of thermoplastic polymer: polymethylmethacrylate, polyvinyl chloride, and polystyrene. Addition of SE increased the fracture strength and water resistance of the composite board to an extent dependent on the polymer species and the composition of wood/SE/polymer. However, water resistance decreased with the increasing proportion of SE when SE meranti was added. Effects of the wood species of SE on the properties of resulting board were small. An increased moisture content of wood flour or SE (or both) increased the variation of board performance.     

Protection of wood particle board against termites

Summary Particle boards are of increasing economic importance. Without special treatment they are destroyed by termites. Deterioration of unprotected material as well as possibilities and present knowledge of preservation against termite attack are briefly described. Recent laboratory experiments with particle board treated to make it resistant to humidity and basidiomycete fungi showed that only one organic preservative out of four protected the boards also against termite attack; one of two water-soluble preservatives gave promising results. Heterotermes indicola (Wasmann) from India proved to be more aggressive and resistant to the preservatives than Coptotermes amanii (Sjöstedt) from Kenya and Nasutitermes nigriceps (Haldemann) from Guatemala. Kalotermes flavicollis (Fabr.) from Italy was also very tolerant to the fungicidal preservatives. Further development of treatments of particle board against termites is required.Part of this paper was prepared for the World Consultation on the Use of Wood in Housing, Vancouver, B. C., Canada, July 5–16, 1971.     

Effect of nanoclay on some applied properties of oriented strand board (OSB) made from underutilized low quality paulownia (Paulownia fortunei) wood

In this study, the effect of nanoclay on some applied properties of oriented strand board (OSB) made from underutilized low quality paulownia wood was investigated. Organo-modified montmorillonite (MMT) at four levels (0, 1, 3 and 5?%) was added to urea formaldehyde (UF) resin. Some chemical properties of paulownia wood (holocellulose, cellulose, lignin and ash contents, pH value and hot and cold water solubility), mechanical [modulus of rupture (MOR), modulus of elasticity (MOE), internal bond strength, screw and nail withdrawal strengths], physical (water absorption and thickness swelling) properties and formaldehyde emission of the strand boards were evaluated. Mechanical properties of all panels complied with the general-purpose OSB minimum property requirements of European Norm. With increasing 5?% nanoclay to UF resin, mechanical and physical properties of the resulting panels improved and formaldehyde emission decreased. However, none of the panels satisfied the thickness swelling and water absorption requirement. The results of X-ray diffraction and transmission electron microscope analysis confirmed the good dispersion of nanoclay in the resulting OSBs. Using paulownia as a fast-growing underutilized species not only can sustain the forests but also can supply raw material to countries facing shortage of wood.     

竹木复合定向刨花板强度性能研究

本文论述了竹材、意大利杨复合定向刨花板的强度性能,就胶种、刨花厚度、竹材所占比率、板密度、板坯结构、施胶量等诸因子对板材强度性能的影响进行了探讨。结果表明:(1)胶种对竹木复合定向刨花板的强度影响不大;(2)降低刨花厚度或提高板密度均可使板材强度提高;(3)单层结构的复合定向刨花板强度最高;(4)提高板材中竹材的比率可使板子强度明显改善;但竹材比率过高时,板材强重比反而下降,呈开口向下的抛物线型变化;(5)酚醛树脂定向刨花板的强度随原料酸性增大而降低。     

Evaluation of decay resistance of wood products made from borax-impregnated wood and bonded with a formaldehyde-free cornstarch and tannin adhesive

? At present, the production of wood composites mainly relies on the petrochemical-based and formaldehyde-based adhesives such as phenol-formaldehyde (PF) resins and urea-formaldehyde (UF) resins, which are non-renewable and therefore ultimately limited in supply.

? This paper concerns the decay resistance of wood products bonded with a new, environment-friendly adhesive derived from abundant and renewable cornstarch and tannin. To improve the total resistance of the composite against both Coriolus versicolor and Coniophora puteana rot fungi, borax (di-sodium tetraborate) was added in proportions of 0.5%, 1% and 2% (w/w) to the cornstarch-tannin adhesives.

? The results show that increasing the concentration of borax in the adhesive decreased the mechanical properties of the composite. The best way to avoid this problem was to use wood impregnated with borax.

? Biodegradation studies were conducted on new composites, first without any treatment, followed by borax at 0.5% aqueous solution treatment. The results show that wood impregnated with borax, in the presence of tannin and sodium hydroxide in the adhesive improves the total resistance of the wood composite against both Coriolus versicolor and Coniophora puteana rot fungi.

     

Properties of PP/wood flour/organomodified montmorillonite nanocomposites

In this research, composites based on polypropylene (PP), beech wood flour, and organomodified montmorillonite (OMMT) were prepared and characterized for their properties. The blend nanocomposites were prepared by melt mixing of PP/WF at 50% weight ratios with various amounts of OMMT (0, 3, and 6 per hundred compounds (phc)) in a Hakee internal mixer. Then the samples were made by injection molding. The influence of organomodified montmorillonite contents on clay dispersion, physical and mechanical properties of PP/wood flour composites were investigated. Results indicated that the flexural strength and modulus, tensile strength and modulus increased by addition of 3 per hundred compounds (phc) of organomodified montmorillonite (OMMT), but decreased with 6 phc OMMT addition. However, impact strength, water absorption and thickness swelling of the composites decreased with increasing nanoclay loading. X-ray diffraction patterns (XRD) and transmission electron microscopy (TEM) revealed that the nanocomposites formed were intercalated. Also, morphological findings showed that samples containing 3 phc of OMMT had higher order of intercalation.     

SEBS-g-MAH和原位接枝MAH对木粉/废旧塑料混合物复合材料力学性能的影响研究

由聚丙烯（PP）、高密度聚乙烯（HDPE）和聚苯乙烯（PS）组成的混合废旧塑料与木粉经高速混合机混合后,采用双螺杆/单螺杆串联挤出机组制备了木粉/混合废旧塑料复合材料。探讨了马来酸酐接枝苯乙烯-乙烯/丁烯-苯乙烯嵌段共聚物（SEBS-g-MAH）和原位接枝马来酸酐（MAH）对木粉/混合废旧塑料复合材料力学性能的影响。结果表明,与使用MAH和DCP的原位反应共混相比,SEBS-g-MAH显著提高了复合材料的抗冲击性能,但对拉伸和弯曲性能的改善不如原位反应共混显著。总的来说,混合废旧塑料制备的复合材料的力学性能要低于纯塑料混合物制备的复合材料,尤其是拉伸断裂伸长率。微观形态研究表明,添加SEBS-g-MAH和原位接枝MAH均可提高木粉与塑料混合物之间的界面相容性,但与添加SEBS-g-MAH相比,原位接枝MAH能更好的改善PP、HDPE、PS与木粉之间的界面结合。原位接枝MAH可被看作是一种改善木粉与塑料混合物间界面相容性的有效途径。此外,采用动态力学分析（DMA）进一步表征了复合材料的储能模量和阻尼因子。     

Dynamic-mechanical analysis and SEM morphology of wood flour/polypropylene composites

Introduction It is well known that over the past few decades, polymers have replaced many conventional materials, such as metal and wood in many applications. This is due to the advantages of polymers over conventional materials (Maurizio et al. 1998; Adr…     

Thermoplastic flow behavior of steamed wood flour under heat and compression

In this study the thermoplastic flow behavior of steamed wood flour was investigated. First it was demonstrated that steamed Japanese beech flour flowed out of the nozzle under compression at high temperature in a thermal flow test with a capillary rheometer. The effects of the steaming temperature, steaming time, compressive pressure, and moisture content of wood flour on the thermal flow temperature were examined. It was shown that the higher the steaming temperature and compressive pressure, the lower the thermal flow temperature. Also, the thermal flow temperature of the sample steamed at 200°C for 20 min became lowest and increasingly higher over time. Furthermore, the thermal flow temperature became linearly low with increasing moisture content of the sample under 15%, whereas it became essentially constant over 15%. It is clarified that compressive pressure and moisture content as well as the steaming conditions profoundly affect the thermoplastic flow behavior of steamed wood flour.     

Movement in a board of impermeable wood during drying

 Creep and sorptive-mechano-effect are defined in terms of complementary partial derivatives. The nett strain and the distribution of mechanical strain in a board of rectangular cross-section is predicted where the board is dried by the progression of a square front. The effects of creep and sorptive-mechano-effect are considered separately and when both are effective. Received 20 September 1999     

General Situation of Wood Resource Utilization and Processing of Recycled Fibers in China

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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 properties 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.