无机镁铝水滑石制备阻燃MDF的性能分析

采用无机镁铝水滑石阻燃剂(Mg Al-LDH)制备阻燃中纤板(MDF),探讨其用量对MDF阻燃及力学性能的影响,并与三聚氰胺磷酸盐(MP)进行对比。结果表明:随着Mg Al-LDH添加量增加,其阻燃抑烟作用更明显;添加量为15%时,其阻止热量释放效果达到MP添加量10%的效果,但抑烟性更优。添加Mg Al-LDH,可使MDF的力学强度降低,但添加量为10%时,阻燃MDF的力学性能仍满足GB/T 11718-2009普通型产品的要求。     

阻燃桉树胶合板的初步研究

以磷酸二氢铵（MAP）溶液为阻燃剂,通过浸泡尾叶桉单板,研究了单板的载药量;以Ⅱ类胶合强度为指标,利用正交试验对常规胶合板生产工艺进行了优选。在此基础上,选取浸泡时间和最优生产工艺试制了阻燃桉树胶合板,并对其Ⅱ类胶合强度和燃烧性能进行了检测。结果表明：不同厚度尾叶桉单板的载药量随浸泡时间的延长呈现相似的增长规律;试验所得常规尾叶桉胶合板最优生产工艺为施胶量210 g.m-2、热压温度130℃、热压时间8 min,该条件下胶合板的Ⅱ类胶合强度达到了2.01 MPa;单板浸泡8h后,单板平均载药量为32.05 kg.m-3,所制得阻燃胶合板氧指数提高了13.9%,炭化长度减少了8.3 mm（26.2%）,阻燃性能明显提高,而胶合强度也达到了Ⅱ类胶合板的国家标准。研究初步证明利用常规桉树胶合板生产工艺生产阻燃桉树胶合板是可行的。     

热处理对MDF力学性质的影响

对市场随机购买的中密度纤维板(MDF)进行热处理,以期改善其力学性质.采用全因素试验方法,对影响MDF热处理效果的因子进行了分析.结果表明:热处理温度、时间,以及不同的生产厂家和产品厚度,对板材的主要力学性质指标可产生一定的影响.建议:当产品中的胶黏荆未完全固化时,可以采用热处理工艺以提高其内结合强度.     

制板因素对FRW阻燃中密度纤维板性能的影响

制板因素对阻燃中密度纤维板(MDF)各项性能的影响至关重要.根据前期试验,选取阻燃剂施加量和热压温度两个主要的制板影响因素,分别探讨了该因素对FRW阻燃中密度纤维板物理力学性能和阻燃性能的影响.研究结果表明:阻燃剂施加量对FRW阻燃中密度纤维板的物理力学性能影响较小,并且所有物理力学性能指标均达到并超过了中密度纤维板国家标准GB/T11718-1999的要求;而阻燃剂施加量对FRW阻燃中密度纤维板的阻燃性能影响较大,氧指数与阻燃剂施加量之间具有显著的相关性.热压温度除对FRW阻燃中密度纤维板的几个指标略有影响外,对其他的物理力学性能指标和氧指数几乎无影响.     

增强型酚醛泡沫板的性能

以阻燃中密度纤维板(MDF)和无纺布为增强材料,对酚醛泡沫板进行表面增强,并对增强型酚醛泡沫板的力学性能和释烟特性进行对比分析.结果表明,MDF增强酚醛泡沫板的综合性能较优,不仅克服了酚醛泡沫表面强度低、易脱粉掉渣问题,表现了木质材料特有的自然特性,而且力学性能及释烟特性优良,压缩强度、抗弯强度、冲击韧性和烟密度均达到JC/T 1051-2007《铝箔面硬质酚醛泡沫夹芯板》的要求.     

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.     

不同纤维制备中密度纤维板及其力学性能研究

研究了由橡木纤维和回收的废旧瓦楞纸纤维混合制备的中密度纤维板(MDF)的阻燃性能,讨论了阻燃剂氢氧化铝(ATH)对MDF的内结合强度(IB)、膨胀率和吸水性等力学性能的影响。试验结果表明:随着ATH用量的增加,MDF的极限氧指数(LOI)增大,表明加入适量的ATH能提高MDF的阻燃性能。当MDF中不含树脂时,其IB值会随ATH用量增加而增大,并随回收的废旧瓦楞纸纤维用量的增加呈递增趋势;树脂的加入,提高了MDF的粘接强度,降低了MDF的膨胀率和吸水率;但当回收的废旧瓦楞纸纤维用量增大时,MDF面板的膨胀率也增大。     

改性酚醛树脂对铝箔贴面中密度纤维板性能的影响

为扩大中密度纤维板(MDF)的应用领域和附加值,进行了将改性酚醛树脂用于MDF的铝箔贴面试验,探究改性酚醛树脂对板材性能的影响.结果表明,贴面MDF的表面胶合强度均达到1 MPa以上,静曲强度、弹性模量和浸渍剥离性能,亦符合行业标准LY/T 1983-2011中对金属(铜箔、铝箔)饰面人造板的要求.     

磷酸三聚氰胺复配硼酸锌阻燃中密度纤维板的燃烧性能

选用磷酸三聚氰胺与硼酸锌复配,制备阻燃中密度纤维板(MDF),并采用锥形量热仪测试其燃烧性能,分析复配阻燃剂对板材燃烧性能的影响.结果表明:复配阻燃剂可有效提高MDF试材的阻燃抑烟性能,降低其热释放速率、总热释放量、产烟速率、总产烟量、CO及CO2生成速率,以磷酸三聚氰胺和硼酸锌等质量复配时,MDF试材的阻燃效果最优.     

不同人造板意杨基材对薄木饰面板浸渍剥离性能的影响

以意杨中密度纤维板(MDF)和意杨刨花板(PB)为基材进行硬枫薄木饰面,研究饰面板加工工艺对2种不同基材的饰面板性能的影响.结果表明,含水率和表面胶合强度测试均能达到国家标准要求;而浸渍剥离强度受热压温度的影响最显著,热压温度越高浸渍剥离值越低,110℃时能达到国标要求.热压温度、热压时间、涂胶量和单位压力是影响2种基材饰面板浸渍剥离的先后因子,且优化工艺基本一致.说明两种不同基材进行薄木饰面的加工工艺对板材浸渍剥离性能的影响不大,在实际生产中可以不考虑意杨MDF和PB基材种类的变化.     

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.