纳米SiO_2对杨木强化材有害气体控制作用研究

将不同质量分数的纳米SiO_2在超声波作用下与脲醛树脂溶液共混制作杨木强化材,测试其TVOC与甲醛释放量及力学性能,并利用扫描电镜/能谱仪分析纳米SiO_2添加量影响处理材环保性能和力学性能的机理。结果显示:纳米SiO_2的添加可以有效地降低处理材TVOC和甲醛的释放量、提高力学强度,且添加量显著地影响强化材TVOC和甲醛的去除率及力学性能。随着用量的增加,对TVOC、甲醛的控制效率和试件力学性能随之升高,但当添加量达0.5%后,以上各项性能有所降低。当纳米SiO_2添加量为0.5%时,对杨木处理材的TVOC和甲醛的控制效果最佳,且力学强度最佳。扫描电镜/能谱仪分析结果显示:纳米SiO_2的添加不影响脲醛树脂在木材中的渗透性,但当纳米SiO_2添加量达到1.0%时,从电镜扫描图上可明显观察到纳米颗粒与树脂聚集形成的团状颗粒,导致其处理效率降低。     

复合型脲醛树脂固化剂的初步研制

报道一种多组分复合型固化剂研制的初步结果。该复合型固化剂除ＮＨ４Ｃｌ组分外，尚含有木材表面活化剂Ａ、甲醛清除剂Ｂ和其它助剂Ｃ。其中表面活化剂Ａ通过提高木材与胶粘剂之间的交联程度而提高胶合强度，同时该表面活化剂也有助于提高树脂固化速度；甲醛清除剂Ｂ可进一步降低板材甲醛释放量；助剂Ｃ可提高热压过程中板坯芯层温度，这对提高热压效率和提高胶粘剂固化程度均有积极影响。     

细木工板甲醛捕捉设备的设计及其捕捉工艺技术

针对目前细木工板甲醛捕捉剂人工喷涂和简单机械喷涂效率低、不均匀的现状,设计、研制出甲醛捕捉剂喷施的机械化设备,并对其捕捉工艺参数进行研究和细木工板理化性能测定,结果表明:甲醛释放量为E_2级细木工板(2.8 mg·L~(-1)),使用甲醛捕捉设备,用喷施量33.6 g·m~(-2)的W-BC甲醛捕捉剂处理之后,甲醛释放量可以降低到了E_1级水平,对物理力学性能无不利影响。因此,该甲醛捕捉设备适合于机械化处理细木工板,大幅提高了捕捉剂喷施均匀性、加工效率及其产品质量,降低了生产成本。     

思茅松的苯酚液化及树脂化研究

研究了硫酸催化条件下,将恩茅松在苯酚中液化用于制备酚醛树脂的技术工艺,分析了各工艺参数对思茅松液化效率的影响,测定了由液化产物制备的液化木基酚醛树脂的物理化学性质和胶合强度。结论如下：1）．液比、反应温度、时间和木粉目数是影响液化反应效率的重要因素,液化产物的残渣率均随上述工艺参数值的升高而降低。2）．残渣含量对树脂物化性质和胶合强度均有影响,残渣含量降低,树脂粘度减小,聚合时间缩短,游离酚含量降低,胶合强度升高。3）．甲醛／苯酚摩尔比对树脂的物化性质和胶合强度也有影响,甲醛／苯酚摩尔比增加,树脂粘度增加,聚合时间减少,游离酚含量减低,胶合强度升高。     

阻燃型杉木间伐材层压板的制造

探讨了在由双氰胺、磷酸、硼化物等配制的阻燃剂处理的杉木间伐材单板生产阻燃型层压板的工艺和性能.分析了各阻燃处理材的阻燃性能和热压工艺对杉木间伐材层压板胶合强度的影响,并检测了甲醛释放量.结果表明:该阻燃层压板达到了国标难燃一级标准;其胶合强度和游离甲醛两项指标均达到室内用材的要求.     

纳米蒙脱土改性脲醛树脂制备胶合板研究

采用纳米层蒙脱土（MMT）改性脲醛树脂制备胶合板,研究MMT在脲醛树脂合成过程中的加入方式、种类以及加入比例对胶合强度和甲醛释放量的影响.结果表明：MMT在脲醛树脂合成中加入第一批尿素（U1）,其干湿强度达到最高,游离甲醛含量最低,且都满足国家标准.对于5种不同处理MMT改性脲醛树脂进行试验,结果显示加入纳米蒙脱土后,胶合板的胶合强度均比脲醛树脂有所提高,游离甲醛有所降低,并达到E0级国家标准.综合强度和成本问题编号为DK-1N的MMT制备的胶合板,其干湿强度分别达到了3.74 MPa和1.79 MPa,板材的游离甲醛含量为0.494 mg/100 g.     

污泥干化冷凝废水电化学脱氮试验研究

利用穿透式电化学反应器对污泥蒸汽热干化冷凝废水进行了氨氮脱除处理,结果表明：无论是在酸性还是碱性环境下,氨氮的去除效果均很理想,去除效率>99.8%。弱碱性环境更有利于加速氨氮脱除,反应90 min即可达到出水技术指标;弱碱性环境下电化学脱除氨氮的能耗是酸性环境下的65%,故推荐在碱性环境下对氨氮进行电化学脱除。由于处理污泥来源及干化参数不同相差较大,污泥干化过程中冷凝废水水质差别也较大,从环境经济效益最大化来考虑,需要根据水质不同选取合理的废水处理方式使得废水实现达标排放。研究结果可为污泥干化冷凝废水的处理提供参考。     

纳米SiO2改性脲醛树脂的研究

在纳米SiO2改性脲醛树脂研究中，探讨了纳米SiO2用量、纳米SiO2表面处理剂、分散工艺等因素对UF树脂黏度、游离甲醛含量、胶合强度的影响。性能测试结果表明：改性后的UF树脂黏度增大，游离甲醛含量下降，胶合强度显著提高。用1％硅烷偶联剂KH-550处理的纳米SiO2(HTSi-04)对UF树脂改性效果显著；采用树脂合成后机械共混的分散工艺的改性效果最好。     

微波等离子处理对脲醛胶性能的影响

脲醛树脂胶粘剂是木材加工领域应用最广泛的胶粘剂,在保障其胶合性能的前提下降低脲醛胶的甲醛释放量是社会关注的焦点和难点。通过试验,研究不同的微波等离子处理方法对脲醛树脂胶粘剂的固化时间、适用期、胶合强度、游离甲醛含量的影响。试验结果表明:等离子处理对脲醛树脂胶粘剂的固化时间和适用期的影响不明显;合适的等离子处理条件可以改善脲醛胶的胶合性能;与未经等离子处理脲醛胶相比,等离子处理后脲醛胶的游离甲醛含量显著降低。     

甲醛捕捉剂在刨花板生产中的应用

对添加甲醛捕捉剂对刨花板各项物理力学性能影响的研究结果表明,甲醛捕捉剂对刨花板释放甲醛的吸收效果比较明显,但随着甲醛捕捉剂量的增加,刨花板的内结合强度和表面结合强度有所下降。     

Development of binderless fiberboard from kenaf core

Binderless fiberboards with densities of 0.3 and 0.5 g/cm³ were developed from kenaf core material using the conventional dry-manufacturing process. The effects of steam pressure (0.4–0.8 MPa) and cooking time (10–30 min) in the refining process, fiber moisture content (MC) (10%, 30%), and hot-pressing time (3–10 min) on the board properties were investigated. The results showed that kenaf core binderless fiberboards manufactured with high steam pressure and long cooking time during the refining process had high internal bond (IB) strength, low thickness swelling (TS), but low bending strength values. The binderless fiberboards made from 30% MC fibers showed better mechanical and dimensional properties than those from air-dried fibers. Hot-pressing time was found to have little effect on the IB value of the binderless board at the refining conditions of 0.8 MPa/20 min, but longer pressing time resulted in lower TS. At a density of 0.5 g/cm³, binderless fiberboard with the refining conditions of 0.8 MPa/20 min recorded a modulus of rupture (MOR) of 12 MPa, modulus of elasticity (MOE) of 1.7 GPa, IB of 0.43 MPa, and 12% TS under the optimum board manufacturing conditions. Part of this article was presented at the 54th Annual Meeting of the Japan Wood Research Society, Hokkaido, August 3–5, 2004     

Utilization of pine (Pinus pinea L.) cone in manufacture of wood based composite

Physical and mechanical properties of medium density fiberboards (MDF) made from various mixtures of wood fibers and stone pine (Pinus pinea L.) cones were evaluated using European standards. MDF panels were manufactured using standardized procedures that simulated industrial production at the laboratory. Six panel types were made from mixtures of wood fiber/cone flour, 100/0, 90/10, 80/20, 70/30, 60/40, and 50/50 percents, respectively. Addition of the cone flour into the MDF significantly reduced formaldehyde emission from the panel. In addition, the addition of 10% cone flour also improved water resistance of the MDF panels made using urea–formaldehyde (UF) resin. However, further addition of the cone flour into the panel negatively influenced their water resistance. Flexural properties and internal bond strength decreased with the increase of cone flour content in the panel. The UF resin is the main source of formaldehyde emission from the UF-bonded wood-based panels. Depending on addition of the cone flour in the panels, the formaldehyde emission values ranged from 2.6% to 55.3% lower than the panels made from 100% wood fiber. Based on the findings obtained from this study, pine cone can be used as a renewable biological formaldehyde catcher as an alternative to the traditional formaldehyde catchers for E1 Class MDF manufacture.     

Formation of the density profile and its effects on the properties of fiberboard

Two main types of fiberboards were produced using lauan (Shorea spp.) fibers with an isocyanate resin as the binder; fiberboard with a flat, homogeneous (homoprofile), and typical U-shaped (conventional) density profile along the board thickness. The processing parameters included manipulation of mat moisture content distribution, press closing speed, and hot pressing method. The results are summarized as follows: (1) A larger variation was observed in the peak density (PD) and core density (CD) of fiberboards at 0.5g/cm³ mean density (MD) level than in those at 0.7 g/cm³. Generally, PD showed a greater variation than CD, irrespective of MD level. (2) Boards produced using two-step hot pressing recorded substantially higher PD with reduced CD. (3) Multiple regression analysis showed that CD and PD could be calculated based on the other profile defining factors, and a rough estimation for peak distance and gradient factor was possible. (4) Based on static bending, conventional fiberboard had a higher modulus of rupture (MOR) than the homo-profile board but a similar modulus of elasticity (MOE). (5) At 0.5 g/cm³ the MOR and dynamic MOE of fiberboard increased by up to 67% and 62%, respectively, when the PD increased from 0.5 to 1.07 g/cm³. Similarly, an increase of PD from 0.7 to 1.1 g/cm³ resulted in corresponding increases of 55% and 34% in the MOR and dynamic MOE of 0.7 g/cm³ boards. (6) The internal bond strength and screw withdrawal resistance were almost entirely dependent on the CD and MD, respectively. (7) Homo-profile fiberboards registered higher thickness swelling and water absorption than conventional fiberboards throughout the dry/wet conditioning cycle.     

Applications of wavelet transformation in the nondestructive test of medium density fiberboard

Taking medium density fiberboards (MDF) as samples, the feasibility of the applications of wavelet analysis in a nondestructive test is discussed in this paper. The main results are as follows: the modulus of elasticity of longitudinal resonance, measured by wavelet analysis, can replace the conventional static modulus of elasticity. Their correlation coefficient is significant (p < 0.01). The defect of samples can be judged by wavelet analysis, which is superior because it is a nondestructive test. __________ Translated from Scientia Silvae Sinicae, 2006, 42(10): 91–94 [译自: 林业科学]     

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.     

Manufacture and properties of ultra-low-density fiberboard

Low-density fiberboards with densities ranging from 0.05 to 0.50g/cm³ were manufactured with steam injection pressing. Bond-type and foam-type isocyanate compound resin adhesives were used separately at 10% and 30% resin content levels. Two types of different-size fibers from softwood were used. Mechanical, dimensional, thermal, and sound insulation properties of the fiberboards were tested. The results are as follows: (1) Bond-type isocyanate adhesive showed higher mechanical and dimensional properties of low-density fiberboards than the foam-type adhesive. (2) Fiberboards produced from small fibers have better mechanical and dimensional properties than those made from large fibers. (3) Thermal conductivity of fiberboards depends more on the board density than on the type of resin or fiber dimension. At a board density lower than 0.2 g/cm³, the thermal conductivity is almost equivalent to those of thermal insulation materials such as polystyrene foam and rock wool, (4) Generally, the sound absorption coefficient of low-density fiberboards tends to increase at higher sound frequency. As the board thickness increases, low-frequency sounds are more readily absorbed by boards.Part of this report was presented at the 46th annual meeting of the Japan Wood Research Society, Kumamoto, April 1996     

Preparation and properties of waste tea leaves particleboard

Urea-formaldehyde (UF) adhesive is the main source of formaldehyde emission from UF-bonded boards. The components in waste tea leaves can react with formaldehyde to serve as a raw material in the production of low formaldehyde emission boards. In our study, waste tea leaves and UF adhesive were employed in the preparation of waste tea leaves particleboard (WTLB). An orthogonal experimental method was applied to investigate the effects of process parameters on formaldehyde emission and mechanical properties of WTLB. The results indicated that: 1) waste tea leaves had the ability to abate formaldehyde emission from boards; and 2) density of the WTLB was a significant factor affecting its modulus of rupture (MOR), modulus of elasticity (MOE) and internal bonding (IB).     

脲醛树脂-钠基蒙脱土插层材料改性速生杨木的研究

为了提高速生杨木的综合性能,以脲醛树脂/钠基蒙脱土(UF-Na-MMT)插层复合材料为改性液进行改性处理.结果表明:速生杨木的密度、尺寸稳定性以及力学性能均能得到明显改善;随着改性液中Na-MMT比例的增加,其抗弯强度、抗压强度、弹性模量不断增加;当Na-MMT的用量为14%、UF树脂的用量为20%时能获得较好的改性效...     

Effect of accelerated aging treatment on a surface property and dynamic mechanical properties of commercial wood-based panels

Changes in surface property and mechanical properties in commercial particleboards and medium density fiberboards subjected to repetitive relative humidity treatment (i.e., aging treatment) were investigated. The stylus technique was used to evaluate surface roughness and a non-destructive vibrational test was used to evaluate dynamic bending strength during aging treatment. These methods evaluated the effect of aging treatment effectively. The aging treatment increased surface roughness and loss tangent (tan δ) values, but decreased dynamic modulus of elasticity (E _d) values of the panels compared to the respective initial values. The increment of surface roughness and E _d degradations observed were larger than the tan δ degradations. Surface roughness and tan δ seemed to be relatively dependent on resin type, whereas E _d was relatively independent under the aging treatment. Overall, the medium density fiberboard bonded methylene diphenyl diisocyanate (MDF(MDI)) panel was superior among the types of panels studied under the aging treatment. There was strong correlation between average roughness (R _a) increment and E _d retention.     

低甲醛释放蔗渣中密度纤维板用脲醛树脂

以脲醛树脂结构形成特征为基础,研制了一种甲醛释放量低、内结合强度高的适用于蔗渣中密度纤维板生产的脲醛树脂胶粘剂。使用结果表明,所压制的蔗渣中密度纤维板物理力学性能达到国家标准要求,甲醛释放量可控制在２０ｍｇ／１００ｇ左右。