水泥刨花板快速固化工艺的初步研究

为缩短水泥刨花板的压制时间，提高生产效率，探讨了通过施加一种添加剂使得水泥刨花板快速固化的工艺。主要研究了快速压制工艺因素及其对制品性能的影响。结果表明，该法可大幅度降低水泥刨花板的压制时间，板材具有较高的脱模强度。     

酚醛胶pH值对刨花板尺寸稳定性的影响

实验对酚醛胶ｐＨ值对刨花板尺寸稳定性和力学强度的影响进行了研究，共对５种ｐＨ值水平，７个类型，计２１块实验室压制的刨花板进行了测试。用高碱酚醛胶压制的刨花板表现出高吸水性，相对较高的厚度膨胀，但很低的不可逆厚度膨胀。结果表明，碱在胶—木胶合系统中存在增强了板坯内应力的释放，同时也增加了吸水率。     

向日葵秆制备刨花板工艺研究

为了用向日葵秆制备性能优越的刨花板,本研究在不同的工艺参数下压制了12块刨花板样本进行比较,得出板材压制的最佳工艺参数分别为;热压温度155℃,热压压力4．0-5．0MPa,热压时间5-6min。并且采用了无毒脲醛树脂胶黏剂。该项技术具有环保、廉价、投资少等优点。     

阻燃酚醛树脂胶阻燃性能的研究

通过对酚醛树脂胶和阻燃酚醛树脂胶热重和微商热重分析、DSC分析结果的比较,对阻燃酚醛树脂胶的耐热性能作了研究。采用阻燃胶压制刨花板,对板子的阻燃和物理力学性能做了测试,并对制板工艺进行了优化。     

生产优质酚醛刨花板新途径—双重压制

采用双重压制新工艺压制出８种２４张优质酚醛刨花板。经常规压制的刨花板，再在１７０℃下进行二次热压１０ｍｉｎ或２０ｍｉｎ。据对板材各种物理性质的测定结果表明：刨花板经１０ｍｉｎ的处理即可显著降低吸水厚度膨胀率和不可逆厚度膨胀率，其原因为机械吸附蠕变和碱，热塑化作用，促使木－胶系统内锁的应力释放。     

水热处理对废弃刨花板的刨花形态及其再循环利用性能的影响

刨花形态和刨花板的再循环利用在再生刨花板的制造过程中具有重要作用。本文讨论了在备料前对废弃刨花板进行热处理的新工艺,分析了水热处理工艺对再生刨花的形态、吸水性及再胶合性能的影响。研究结果表明,采用水热处理工艺制备的再生刨花所压制的刨花板性能接近于原生刨花板;再生刨花有良好的再胶合性能。     

利用废弃浸渍纸制造刨花板的试验研究

利用废弃浸渍纸粉末替代部分脲醛树脂胶压制刨花板,采用正交试验方案并考察刨花板的主要理化性能,探讨浸渍纸粉末部分或全部替代脲醛胶的可行性。结果表明:废弃浸渍纸粉末用量为20%、脲醛树脂用量为5%、热压温度为190℃、热压时间为0.4 min/mm时,所压制的刨花板静曲强度为17.97 MPa,内结合强度为0.76 MPa,甲醛释放量为5.69 mg/100g,废弃浸渍纸粉末可部分替代脲醛树脂压制刨花板且性能较佳。     

废旧刨花板循环利用技术的研究

探讨利用废旧刨花板循环制造刨花板的技术.采用高压水煮、水煮、汽蒸和直接粉碎4种方法制备刨花,通过比较刨花的筛分值和压制刨花板的主要物理力学性能,得出最佳的处理方法为水煮.试验压制的一次循环水煮和二次循环水煮刨花板的性能,可分别达到GB/T 4897.5-2003和GB/T 4897.3-2003的要求.     

利用果树枝丫材制造刨花板

利用果树枝丫材制造刨花板希腊亚里士多德大学林学院试验用果树枝丫材制造刨花板获得成功。实验中压制单层和三层结构刨花板，枝丫材和成材的重量比分别为１００：０，７５：２５，５０：５０，２５：７５及０：１００。试验结果表明，对三层结构刨花板而言，芯层枝丫材的...     

刨花板用环保胶黏剂的制备与性能研究

将工业化生产的生物油与聚合4,4’-二苯基甲烷-二异氰酸酯(PMDI)按不同比例混合,并加入一定量的稀释剂形成稳定的PMDI/生物油胶合体系,以此体系作为胶黏剂压制单层结构刨花板,探讨胶黏剂施加量、PMDI/生物油混合比、稀释剂加入量等对刨花板内结合强度、静曲强度、弹性模量、吸水厚度膨胀率、吸水率等物理力学性能的影响。结果表明:加入稀释剂有效地降低了PMDI/生物油体系的黏度,提高了体系在施胶过程中的雾化效果;PMDI/生物油混合比为25∶75的胶黏剂压制的刨花板具有与纯异氰酸酯胶黏剂压制刨花板相似的性能。     

Morphological and kinetic parameters of the absorption of nitrogen forms for selection of Eucalyptus clones

Eucalyptus clones are selected according to productivity,wood quality,rooting capacity,and resistance to drought,frost and diseases.However,kinetic and morphological parameters that determine the absorption efficiency of nutrients such as nitrate(NO_3~-) and ammonium(NH_4~+)are often not considered in breeding programs.The objective of this study was to evaluate the morphological,physiological and kinetic parameters of nitrogen uptake by clones of Eucalyptus saligna(32,864) and Eucalyptus grandis(GPC23).Morphological parameters in shoot and root systems,biomass and N concentrations in different organs,photosynthetic pigment concentrations,parameters of chlorophyll a fluorescence and photosynthetic rates were evaluated.Kinetic parameters,maximum absorption velocity(V_(max)),Michaelis-Menten constant(K_m),minimum concentration(C_(min)) and influx(I) were calculated for NO_3~-and NH_4~+ in the two clones.E.granais clone was more efficient in the uptake of NO_3~-and NH_4~+,and showed lower K_m and C_(min)values,allowing for the absorption of nitrogen at low concentrations due to the high affinity of the absorption sites of clone roots to NO_3~-and NH_4~+.Higher root lengths,area and volume helped the E.grandis clone in absorption efficiency and consequently,resulted in higher root and shoot biomass.The E.saligna clone had higher K_m and Cmin for NO_3~-and NH_4~+,indicating adaptation to environments with higher N availability.The results of NO_3~-and NH_4~+ kinetic parameters indicate that they can be used in Eucalyptus clone selection and breeding programs as they can predict the ability of clones to absorb NO_3~-and NH_4~+ at different concentrations.     

The effects of different nitrogen sources on camptothecin content and related gene expression in Camptotheca acuminata seedlings

Camptotheac acuminata Decne is a unique tree species in China with an important secondary metabolite,camptothecin(CPT),used in the treatment of cancer.Nitrogen(N) is an important element that affects plant growth and the accumulation of CPT.Reports on the effect of N on CPT synthesis from a genetic perspective are scarce.To explore the effects of different N sources and levels on CPT synthesis in C.acuminata,two-year-old seedlings were fertilized with different concentrations of pure ammonium sulphate,source of ammonium N(NH_4~+-N),and potassium nitrate for nitrate N(NO_3~--N).Concentrations of 2.5,5,7.5,and10 g pot~(-1) NH_4~+-N and NO_3~--N were used.The results showed that 7.5 g NH_4~+-N and NO_3~--N treatments were best for growth and fresh weight of leaves.Compared with the other treatments,the CPT content,tryptophan synthase and tryptophan decarboxylase activities,and expression of the CaTSB and CaTDCl genes under the 2.5 g NH4+-N and NO_3~--N treatments peaked significantly at 30 days.However,the expression of CaTDC2 surpassed that of the other two genes at 60 days.Therefore,compared with NH4+-N source,the NO_3~--N source was more beneficial for growth,and NO_3~--N was better for CPT yield.Consequently,leaves of C.acuminata treated with 2.5 g NO_3~--N could be harvested after 30 days to obtain maximum CPT content.CaTDC1 is more closely linked to CPT synthesis.The results of this study improved the production of CPT in C.acuminata via fertilization.     

Effect of nitrogen addition on DOC leaching and chemical exchanges on canopy leaves in Guangdong Province,China

The impact of nitrogen(N)deposition on dissolved organic carbon(DOC)fractions in throughfall is not well understood.We performed a laboratory experiment and compared DOC leaching from canopy leaves after dipping leaves in pure water(control)and NH4NO3 solution(N-treatment)for 18 h.Net changes of DOC,NH4^+,NO3^-,SO4^2-,K^+,Mg^2+,Ca^2+and H^+contents after dipping leaves were determined by comparing solutions with and without leaves.We recorded no differences of DOC leaching between control and N-treatment,implying that N deposition had minor impacts on canopy DOC production.This confirmed that previous experiments testing the effects of N addition on DOC dynamics without considering the effects of the canopy reaction successfully described the real situation.We also confirmed the previously-reported canopy exchange process in spite of a high background N deposition at our study site.N-treatment significantly increased base cation leaching,especially K^+,and the increase was positively correlated with foliar NH4?retention.Net leaching of H^+and SO4^2-was not affected by the N-treatment.     

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     

铅笔板高温热压改性技术研究

为克服高温烤板处理的缺点 ,进行了椴木铅笔板热压干燥基本规律及温度、时间与含水率的关系研究和热压干燥的铅笔板与烤板的吸湿性、脆性对比试验。研究结果表明 :高温热压可使木材进行热分解 ,热压干燥后的铅笔板的吸湿性和脆性能达到烤板的要求 ,并在质量稳定性方面优于烤板 ,更重要的是它解决了烤板对环境的污染问题     

鸡冠花试管开花初探

以鸡冠花种子为外植体获得无菌苗进行试管开花实验,结果表明:植物激素影响鸡冠花试管花形成发育,以6-BA 1.0mg/L+NAA0.2mg/L为促进试管苗开花的最适激素浓度组合;环境条件影响植物的开花,随着光照强度的提高,试管苗开花率提高,花色更鲜艳;营养水平不同对开花有影响,培养基中的大量元素减半,NH_4NO_3含量减半,均利于试管开花。     

热压水泥刨花板工艺的研究

本文主要论述了热压法制造水泥刨花板的工艺。试验选取热压温度、热压时间、水灰比、灰木比、添加剂和板子密度等工艺变量建立多元回归方程,并对刨花形态等问题进行了讨论。试验结果表明:热压温度和刨花形态对板子性能影响极为显著;热压法水泥刨花板不仅具有与冷压法相同的物理力学性能,而且还具有水泥水化速度快、板坯脱模强度较高等特点,因而缩短了水泥刨花板的生产过。     

Effects of six years of simulated N deposition on gross soil N transformation rates in an old-growth temperate forest

Elevated atmospheric nitrogen(N) deposition has been detected in many regions of China, but its effects on soil N transformation in temperate forest ecosystems are not well known. We therefore simulated N deposition with four levels of N addition rate(N0, N30, N60, and N120) for6 years in an old-growth temperate forest in Xiaoxing'an Mountains in Northeastern China. We measured gross N transformation rates in the laboratory using ~(15)N tracing technology to explore the effects of N deposition on soil gross N transformations taking advantage of N deposition soils. No significant differences in gross soil N transformation rates were observed after 6 years of N deposition with various levels of N addition rate. For all N deposition soils, the gross NH_4~+ immobilization rates were consistently lower than the gross N mineralization rates,leading to net N mineralization. Nitrate(NO_3~-) was primarily produced via oxidation of NH_4~+(i.e., autotrophic nitrification), whereas oxidation of organic N(i.e., heterotrophic nitrification) was negligible. Differences between the quantity of ammonia-oxidizing bacteria and ammonia-oxidizing archaea were not significant for any treatment, which likely explains the lack of a significant effect on gross nitrification rates. Gross nitrification rates were much higher than the total NO_3~- consumption rates,resulting in a build-up of NO_3~-, which highlights the high risk of N losses via NO_3~- leaching or gaseous N emissions from soils. This response is opposite that of typical N-limited temperate forests suffering from N deposition,suggesting that the investigated old-growth temperate forest ecosystem is likely to approach N saturation.     

竹木复合刨花板制造工艺研究

从胶水类型、施胶方法以及关键工艺参数等方面探讨了竹木复合刨花板的生产工艺,综合结果表明,竹木复合刨花板批量生产的工艺参数为:低摩尔比环保树脂胶、搅拌气流式喷胶法、竹刨花比例40%～60%、用胶量70 kg(干胶)·m-3、热压压力2.0 MPa、热压温度170℃、热压时间20 s·mm-1、刨花颗粒(芯层)0.5～1.0 mm、板厚8.8 mm。生产的竹木复合刨花板产品质量执行国家标准,质量可以达到国标A类刨花板一等品标准。     

吸声保温玉米秸秆穰板制备及性能研究

以疏解后的玉米秸秆穰丝为基材,异氰酸酯为胶黏剂,均匀组坯后经热压制备成吸声保温玉米秸秆穰板。通过单因素试验分别探究了施胶量、热压温度板材密度、厚度对玉米秸秆穰板吸声、导热和压缩性能的影响。结果表明:综合板材的性能和生产成本,优化工艺为施胶量2%、热压温度140℃、密度0.10 g/cm3,所得板材吸声性能达到GB/T 16731—1997的Ⅲ级标准,压缩强度满足GB/T 25975—2010中的要求,属高效保温材料。