表面强化杨木胶合板模板的研究

研究了用酚醛树脂浸渍的杨木单板作表板制造杨木胶合板模板的制造工艺。试验结果表明,这种表面强化的杨木胶合板模板具有较好的表面性能和力学强度,各项性能都优于有关标准的要求;用酚醛树脂浸渍的杨木单板二次覆贴杨木胶合板可使模板的性能较一次胶压更优。     

单板/HDF复合木地板的制造工艺与产品性能研究

单板/高密度纤维板(HDF)复合木地板结合了实木地板和浸渍纸层压木质地板的优点,是地板产业发展的新方向之一。文中以12mm厚HDF为基材、复合意杨单板,试制了"耐磨纸-单板-HDF基材-平衡纸"四层结构地板用复合板材。研究了不同单板厚度、胶黏剂种类(聚氨酯-PU,脲醛树脂-UF)及涂布量对板材翘曲度、吸水厚度膨胀率、内结合强度及机加工性能的影响。结果表明:1)单板与HDF复合制造木地板是可行的;2)复合木地板的翘曲度随单板厚度和施胶量的提高而递增,最高可达约0.6%;3)贴面采用聚氨酯胶黏剂,产品性能优于脲醛树脂胶合板材,但冷压周期偏长。推荐工艺条件为:单板1.2mm,PU或UF胶黏剂均可,涂布量控制在100g/m~2左右。     

PF树脂对二种单板浸渍改性的比较研究

为提高混凝土模板用胶合板的表面耐磨性,采用浸渍方法,在常温、常压下用PF树脂胶液对杨木和马尾松单板进行了改性处理,对胶液种类、浸渍时间与单板增重率、表面磨耗值之间的关系进行了研究,探讨了提高单板表面耐磨性的合适工艺。研究结果表明,单板经浸渍处理后,胶黏剂主要分布在单板表层,随浸渍时间延长,二种单板的增重率呈上升趋势,表面磨耗值呈下降趋势。当浸渍时间相同时,加入耐磨剂的PF树脂胶液,可显著提高单板的表面耐磨性,碳化硅的耐磨性比二氧化硅更明显,杨木单板的表面耐磨性优于马尾松单板。验证试验表明,PF树脂中加入0.4%的碳化硅、0.1%的海藻酸钠和3.5%的微晶纤维素,杨木单板浸渍3 h,马尾松单板浸渍5 h,二者的表面耐磨性可显著提高。     

实木复合地板的表层改性工艺

将表层橡木单板浸渍三聚氰胺树脂后,与桉木单板、三聚氰胺浸渍纸一次热压成型制作多层实木复合地板。采用正交试验方法,探讨橡木单板浸渍工艺及热压工艺对多层实木复合地板表面耐磨性等理化性能指标的影响。试验结果表明:浸渍温度对橡木单板浸渍质量增加率影响显著,浸渍浓度对橡木单板浸渍质量增加率影响一般显著,热压温度对多层实木复合地板的表面耐磨性能影响显著。在试验条件下,以浸渍时间20 min、浸渍浓度40%、浸渍温度45℃、热压温度145℃、热压时间0.8 min/mm、热压压力1.8 MPa和施胶量240 g/m2为较优工艺,压制所得多层实木复合地板的表面耐磨性能等理化性能较佳。     

综合信息

全国人造板标准概况之二(截至2004年12月底) 1　已报批的我国人造板标准　·不饱和聚酯树脂装饰胶合板　·刨切单板　·木材胶粘剂及其树脂检验方法　·木材工业胶粘剂用脲醛、酚醛、三聚氰胺甲醛树脂　·人造板甲醛释放量检测用1立方米气候箱装置　·竹材地板　·集成材地板　·单板层积材　·木塑复合材(挤出成型)2　已审查、待报批的我国人造板标准　·饰面用浸渍胶膜纸　·装饰单板贴面人造板　·浸渍胶膜纸饰面人造板　·人造板甲醛释放量检测用40L干燥器装置　·船用贴面刨花板　·硬质纤维板　·细木工板　·刨切车厢胶合板　·软木…     

杨（桦）木单板树脂浸渍调控系统的开发设计

利用广义神经网络建立了树脂浸渍模型,该模型可实现常压浸渍和辊压浸渍中树种、单板纹理、单板,厚度。树脂固体含量、浸渍时间或辊筒间隙等几方面因素与单板增重率之间的高精度映射,从而进行树脂浸渍量的实时调控。模型相关系数均大于93％,平均相对误差均小于10．2％。     

不同因素对竹/木复合强化单板层积材MOE、MOR的影响

以杨木单板和竹帘为原料,采用低分子量水溶性酚醛树脂浸渍处理,通过干燥、组坯、热压等工艺制备竹木复合强化单板层积材。探讨了组坯方式、压缩率、热压温度、热压时间4个因素对竹木复合强化单板层积材弹性模量(MOE)和静曲强度(MOR)的影响。结果表明:表层为一层竹帘的竹木复合强化单板层积材的MOE和MOR较大,分别是13．43GPa、148．13MPa,与表层为杨木单板次表层为竹帘组坯方式相比分别增加了33．63％、56．16％。确定了竹木复合强化单板层积材较合理的制造工艺参数。     

浸渍纸饰面定向刨花板性能研究

研究了定向刨花板覆以杨木单板和三聚氰胺浸渍纸贴面后的性能，并初步探讨了主要生产工艺参数对饰面定向刨花板性能的影响。研究的结果表明；在定向刨花板和三聚氰胺浸渍纸之间加入一张杨木单板进行一次性压贴在工艺上是可行的，定向刨花板经此法贴面后，物理力学性能明显提高，表面质量明显改善，“映像（telegraphing）”现象消除。     

酚醛浸渍纸贴面杉间材水泥模板制造工艺

介绍了杉木间伐材为原料制造酚醛浸渍纸贴面水泥模板的生产工艺，同时指出了该法为普通马尾松胶合板（模板用）浸渍纸贴面不同之处。     

浸渍胶膜纸及其饰面细木工板的甲醛释放量

以甲醛释放量为E_0级的细木工板为基材,杨木单板为缓冲层,甲醛释放量≤1.5mg/L的A级浸渍胶膜纸为饰面材,制作浸渍胶膜纸饰面细木工板(生态板),分析浸渍胶膜纸与生态板甲醛释放量的相关性。结果表明:生产试验条件制备的生态板,其含水率、表面胶合强度、浸渍剥离、耐冷热循环、耐光色牢度、表面耐龟裂等指标均符合Q/TBB 0022-2016《浸渍胶膜纸饰面胶合板》要求;只有浸渍胶膜纸甲醛释放量≤0.7mg/L时,制备生态板的甲醛释放量≤0.5mg/L,达到E_0级。     

Browsing Damage on Pine (Pinus sylvestris and P. contorta) by a migrating moose (Alces alces) Population in Winter: Relation to Habitat Composition and Road Barriers

In Scandinavia, moose (Alces alces L.) sometimes cause severe browsing damage to economically-important pine. Moose-vehicle accidents have spurred construction of fences along roads, and these may interfere with moose migration between summer and winter ranges, or the road alone may be a barrier. If this happens and moose build up along roads, landowners may suffer economically. Therefore, this study investigated whether roads, fences or other factors influence the use of young pine stands by moose. Eighty stands along roads in northern Sweden were evaluated in which individually-browsed branches were counted on 9972 pines. Moose browsing was not significantly related to birch (Betula pendula Roth, B. pubescens Ehrh.) density, nor did it differ between pines (Pinus contorta Douglas or P. sylvestris L.). However, increased pine density, site productivity and proximity to a highway were associated with increased browsing. Further large-scale studies are needed to understand moose habitat selection and the effects of roads.     

Effects of Root Freezing on the Physiology and Growth of Picea glauca,Picea mariana and Pinus banksiana Seedlings Under Different Soil Moisture Regimes

The root systems of 2-yr-old Picea glauca, Picea mariana and Pinus banksiana seedlings were submitted to various frost temperatures during an artificial frost to induce different levels of root damage. Frost-damaged and control seedlings were placed in a greenhouse under high and low soil moisture regimes. Seedling growth and physiology were evaluated periodically. Seedling survival was reduced when root damage reached levels of 60-80%. Root systems of all three species showed partial to total recovery by the end of the experiment. In general, root freezing damage caused reductions in seedling growth, with these reductions becoming less significant over time. Root damage had little to no effect on black spruce and jack pine seedling physiology, while white spruce CO 2 uptake decreased with increasing root damage. Shoot nitrogen content of all three species decreased slightly with increasing root damage.     

Stand Structure in Pine,Spruce and Deciduous Forests: A Comparison Between Finnish and Russian Karelia

This study investigated the stand structure in pine, spruce and deciduous forests in the border district of Finland and Russia. A total of 46 mature forest stands was selected as pairs, the members of each pair being as similar as possible with respect to their forest site type, age, moisture and topography. The stands were then compared between the two countries by means of basal areas and number of stems. The proportions of dominating tree species were 2-12% lower, and correspondingly the proportions of secondary tree species higher, in Russian forests. The density of the forest stock was also higher in each forest type in Russia. The forests in the two countries differed most radically in terms of the abundance of dead trees. The amount was two to four times higher in Russian deciduous and spruce forests, and in pine forests the difference was 10-fold. The stand structures indicated that Russian coniferous stands, in particular, were more heterogeneous than intensively managed pine and spruce stands in Finland.     

Growth and Terminal Bud Formation in Picea abies Seedlings Grown with Alternating Diurnal Temperature and Different Light Qualities

The root collar diameter and the height:diameter ratio are of particular importance in container-grown seedlings where a high density in the containers may produce spindly seedlings. Temperature regimes and light quality are known to affect plant growth. The aim of this study was to identify responses in Picea abies (L.) Karst. seedlings grown with light providing different red:far-red ratios and under temperature regimes with alternating day (DT) and night temperature (NT) from negative (DT < NT) to positive (DT > NT) difference (DIF) between DT and NT. Experiments were conducted in controlled environment chambers and in a daylight phytotron. Only limited thermoperiodic responses appeared in P . abies seedlings with respect to seedling height and dry weight accumulation. The formation of terminal buds, however, was clearly delayed in seedlings grown at negative DIF. The results indicate a requirement for day extension light that is high in far-red, to prevent terminal bud formation under natural short-day conditions. An extended study should be conducted to clarify the minimum level of light intensity and the optimal light quality needed to prevent terminal bud formation under natural short-day conditions.     

CAD与建筑设计的关系

本文分析了CAD在设计中引起的正面和负面影响,并进行了系统的阐述,从而使设计者在应用中能够保持客观的态度。     

Natural Regeneration in Clear-cuts: Effects of Scarification,Slash Removal and Clear-cut Age

The effects of soil scarification (mounding), slash removal and clear-cut age on the natural regeneration in clear-cuts was evaluated using data from four sites in southern Sweden. The treatments were carried out during a good seed and establishment year for birch ( Betula pubescens Ehrh. and B. pendula Roth). Scarification had the strongest positive effect on the density of naturally regenerated seedlings, especially in birch, but also in pine ( Pinus sylvestris L.) and spruce [ Picea abies (L.) Karst]. Slash removal had a positive effect on birch density. No statistically significant effect of clear-cut age was found. In addition, no statistically significant interactions between clear-cut age and scarification or slash removal were found. The ingrowth of field vegetation was the fastest in areas that were not scarified, less rapid in areas scarified on old clear-cuts, and the slowest after scarification in fresh clear-cuts. In conclusion, it may be possible to control the density of birch during a good establishment year for birch. If birch is desired, the best combination of treatments is to remove the slash and scarify; otherwise, these treatments should be avoided.     

Risk Perception Among Non-industrial Private Forest Owners

Based on an enquiry, risk perception among non-industrial private forest owners is described in relation to climate change and forestry hazards. Of the respondents, 11% took action to remedy the effects of climate change. Out of a given set, hazards were ranked according to each respondent's experience of recent substantial financial loss to the estate and in relation to his or her willingness to make investments aimed at risk reduction. For each hazard, the respondent assessed the risk in four classes ranging from very high to negligible risk. Six hazards were considered most problematic in all three aspects: browsing damage, falling timber prices, damage by wind, spruce bark beetle, root rot and pine weevil. A majority of the respondents claimed to take action to reduce the risk associated with at least one hazard, while 35% did not know whether they did. Excluding climate change, the need for decision support was the largest in relation to damage by wind owing to a combination of perceived high risk and a high level of ignorance in relation to whether risk-reducing measures were taken.     

Interactions in decomposition and N mineralization between tropical legume residue components

In situ produced plant residues contain a mixture of different plant components of varying quality. To assess synergistic or antagonistic interactions occurring during the decomposition and mineralization of such mixtures, individual plant parts (stems, leaves, leaf litter and roots) or the mixture of stems, leaves and leaf litter of the agroforestry species pigeonpea (Cajanus cajan) or of crop residues of peanut (Arachis hypogaea) or of the weed hairy indigo (Indigofera hirsuta) were incubated in pots for 19 weeks. Periodically, remaining plant residues were sieved out (>2 mm), weighed and N content as well as soil mineral N determined. Above- and below-ground residues of peanut decomposed fastest and showed the largest N release in agreement with their high N concentration and low-acid detergent fibre (ADF) : N ratio. Hairy indigo was hypothesized to be of lower quality than pigeonpea because of its high-polyphenol content. However, it decomposed faster than pigeonpea, largely because of the higher N and lower lignin concentration of its components. Ranking of individual plant components for N mineralization resulted in the following pattern, leaves > leaf litter > roots > stems. In mixtures of the different plant components a similar species order in decomposition was obtained, e.g. peanut > hairy indigo > pigeonpea. The amount of N released from the mixture was dominated by stem material that comprised 46–61% of the mixture. The interactions in mixtures were relatively small for peanut (generally high-quality components) as well as for pigeonpea (low proportion of high-quality components, i.e. N rich leaf material). However, a positive interaction occurred during later stages of N mineralization in the mixture of hairy indigo as it had a significant proportion of N rich components and absence of highly reactive polyphenols. Thus, for plants with low to intermediate chemical quality attributes, manipulating plant composition (e.g. by varying harvest age, affecting stem and leaf proportions) will be important to obtain significant interactions during decomposition when its components are mixed.     

Pasture production and tree growth in a young pine plantation fertilized with inorganic fertilizers and milk sewage in northwestern Spain

The use of organic waste materials such as milk sewage as an organic fertilizer could have the dual advantages of organic-waste disposal and reduced dependence on inorganic fertilizers. The effects of fertilization with (1) conventional mineral fertilization, (2) milk sewage sludge at 40 kg N ha⁻¹ target rate and (3) no fertilization on pasture production and tree growth were examined in an experiment consisting of two pasture mixtures under a one-year-old Pinus radiata plantation with a density of 2500 trees ha⁻¹. The two pasture mixtures were: (1) Dactylis glomerata L. var. saborto (25 kg ha⁻¹) + Trifolium repens L. group Ladino (4 kg ha⁻¹) + Trifolium pratense L. var. Marino (1 kg ha⁻¹); (2) Lolium perenne L. var. Tove (25 kg ha⁻¹) + Trifolium repens L. group Ladino (4 kg ha⁻¹) + Trifolium pratense L. var. Marino (1 kg ha⁻¹). The experiment began in the spring of 1995 using a randomized block design with three replicates in Castro Riberas de Lea (Lugo, Galicia, north-western Spain). Plot size was 12 × 8 m², with a 1 m buffer strip between plots. Two-year data showed that fertilization with either material had a positive effect on pasture production, with no significant difference between the two fertilization treatments. Tree growth in the milk sewage sludge plot was significantly higher than in the control plots. Inorganic fertilization increased pasture production, but affected tree growth negatively. The results show that milk sewage sludge could be used as a fertilizer in silvo-pastoral systems. This revised version was published online in June 2006 with corrections to the Cover Date.