核桃壳苯酚液化及其产物树脂化制备木材胶黏剂的研究

采用硫酸催化剂,考察了苯酚与核桃壳质量比等条件对核桃壳液化的影响。结果表明相同液化条件下,随着苯酚与核桃壳质量比从2∶1升至5∶1,残渣率从26.49%降至6.60%;随着浓硫酸加入量从2%增至4%、反应时间从5 min延至120 min、反应温度从100℃增至150℃,残渣率则分别从20.79%降至10.48%、48.84%降至15.62%、28.86%降至9.39%,游离酚含量分别从17.32%降至12.67%、41.71%降至10.25%、21.94%降至14.33%。同时,液化产物重均相对分子质量(MW)可降至706~1 030、分散度可降至1.04~1.25;液化产物中高相对分子质量部分随着苯酚与核桃壳质量比的增加有所降低,但随着浓硫酸加入量、液化反应时间和温度的增加而有所增加;核桃壳液化产物/苯酚/甲醛共缩聚树脂胶黏剂(WPF)与传统酚醛树脂胶黏剂(PF)的对比表明,WPF的胶接强度可达1.33 MPa,可作为胶合板用胶黏剂。     

竹材苯酚液化及胶黏剂制备工艺

采用单因素试验和正交试验研究了竹材加工剩余物的苯酚液化工艺,并进一步研究了竹材苯酚液化产物-甲醛树脂胶黏剂(BPF)的制备工艺和性能。试验结果表明:竹材苯酚液化过程中,液化温度对液化效果的影响最为显著,其次是液比和液化反应时间,催化剂用量2%~4%范围内对液化效果影响不大。竹材加工剩余物苯酚液化的优选工艺为:液固比值3.5、催化剂用量4%、液化温度145℃、液化时间60 min;在此工艺下竹材液化率为99.1%。胶黏剂制备过程中,竹材苯酚液化物与甲醛溶液(甲醛质量分数为37%)的合理质量比为100∶164.8~199.5,其中以100∶182.1较佳。BPF的固化温度低于普通酚醛树脂胶黏剂(PF),因而可在较低温度下固化良好,在130℃或140℃热压温度条件下,用其制备的胶合板的胶合强度均比较理想,热压温度为140℃时的试验结果更佳。     

基于马占相思栲胶单宁酚醛树脂胶黏剂的合成与热压工艺研究

以马占相思栲胶、苯酚、甲醛和氢氧化钠为原料,通过共缩聚反应来制备单宁酚醛(TPF)树脂胶黏剂并对其胶合强度进行检测和分析,利用均匀设计建立指标值与相关因素的方程模型,进一步优化实验配方。结果表明,当苯酚与甲醛的摩尔比为1:2.5,苯酚与栲胶质量比为37:100,质量浓度为30%的氢氧化钠溶液与栲胶质量比为74:100时,合成的TPF共缩聚树脂胶黏剂性能较稳定;压制的三层胶合板强度达1.37MPa,达到国家标准(GB/T 14732—2006)Ⅰ类胶合板的要求。     

热固性PMUF树脂胶黏剂贮存稳定性研究

以酚醛、尿素、三聚氰胺和甲醛为原料,采用缩聚的方法制备了热固性PMUF树脂胶黏剂。考察了原料配比和初始黏度对PMUF树脂贮存稳定性的影响,以及贮存时间对PMUF树脂性能的影响,并采用FT-IR对其进行了表征。结果表明在一定范围内,减少尿素和甲醛的用量,增加苯酚和NaOH的用量,降低初始黏度可以提高PMUF树脂胶黏剂的贮存稳定性。随着贮存时间的增加,PMUF树脂胶黏剂的游离甲醛含量增加,游离苯酚含量减少,黏度变化速率上升,用其压制的胶合板甲醛释放量略有下降。     

木薯秆液化树脂化工艺试验

为实现木薯秆的有效利用,以苯酚为液化剂,硫酸为催化剂,对木薯秆进行液化和树脂化工艺研究。结果表明,木薯秆适宜的液化工艺为:液固比3.5∶1,液化温度160℃,硫酸用量7%,液化时间1.5 h;适宜的树脂化工艺为:甲醛与木薯秆液化产物摩尔比1.8,NaOH与木薯秆液化产物摩尔比0.3,缩聚温度90℃。     

液化木质素磺酸钙基环保酚醛胶黏剂的合成

探讨了加料方式对传统酚醛树脂(PF)胶黏剂游离酚、醛的影响因素.在此基础上,采用热化学酚化技术活化木质素磺酸钙得到木质素磺酸钙酚化产物,将酚化产物代替苯酚制备低成本的木质素基酚醛胶黏剂(LPF).实验结果表明,当甲醛分3次加入、碱液分2次加入时,制备的PF胶黏剂具有较低的游离酚、醛,且以苯酚为液化试剂,液化温度140℃、液化时间15min、苯酚与木质素磺酸钙的质量比(酚木比)为2∶1,酚化工业木质素磺酸钙,将得到的酚化液代替苯酚在酚醛物质的量之比为1∶1.7时,制得的LPF具有更低的游离酚、醛含量、较长的储存期和优异的胶合性能.     

金属离子对大豆基木材胶黏剂胶合性能的影响

使用聚酰胺多胺-环氧氯丙烷树脂(PAE)溶液、脱脂豆粉和金属氯化物溶液调制无醛大豆基木材胶黏剂,采用傅里叶红外光谱、热重分析、胶合板性能评价等方法,探究金属离子种类、用量及其加入方式对大豆胶黏剂胶合性能的影响。结果表明:金属离子对大豆胶黏剂的胶合性能有着重要影响。添加Mg~(2+)与Fe~(3+)能够提高胶接耐水性能,而添加Na~+、Ca~(2+)、Cu~(2+)、Al~(3+)等金属离子会不同程度降低大豆胶黏剂耐水性能;Mg~(2+)可促进大豆蛋白伸展而且不影响PAE树脂的交联特性,使脱脂豆粉能与PAE树脂产生更好的交联反应,赋予大豆胶黏剂更好的胶接耐水性能;当Mg~(2+)添加量为胶黏剂的1.5 wt%(以1 wt%MgCl_2溶液计)时,压制的胶合板28 h"煮-烘-煮"湿强度达到1.16 MPa,较未添加金属离子大豆胶黏剂的湿强度提高11.5%,然而Mg~(2+)的添加顺序对大豆胶黏剂的胶合性能基本无影响。     

湿地松单宁制造胶合板胶黏剂的研究

用湿地松缩合单宁替代部分苯酚研制耐水性胶合板胶黏剂;选定四因素三水平进行正交试验,寻找制备胶合板胶黏剂的最佳工艺条件,探求湿地松缩合单宁胶制备的可行性,以达到充分利用废弃物,降低胶合板胶黏剂的工业生产成本,减少环境污染的目的。本实验研究表明:用湿地松缩合单宁替代40%的苯酚制成的胶黏剂用于压制胶合板,其质量符合Ⅰ类胶合板国家标准。     

芭蕉芋渣苯酚液化物制备酚醛发泡材料

以苯酚为液化剂对芭蕉芋渣进行液化,获得的液化产物树脂化后用于制备发泡材料。探讨液固比、温度、催化剂对芭蕉芋渣液化效果的影响,并分析芭蕉芋渣液化物的树脂化制备发泡材料的性能。结果表明,苯酚与芭蕉芋渣的质量比为6以上获得较好的液化效果;温度在120℃时,残渣率较低;用硫酸(98%)作催化剂比磷酸、盐酸的效果好。芭蕉芋渣液化的最佳工艺条件是液固比6,温度120℃,催化剂为硫酸(98%)、用量5%,液化时间是60 min。制备的芭蕉芋渣树脂的游离甲醛含量为1.09%,可在一定意义上取代酚醛树脂,既能减少成本,又有利于保护环境。     

纤维素乙醇木质素改性酚醛树脂胶黏剂的初步研究

以纤维素乙醇木质素、苯酚、甲醛为原料,氢氧化钠为催化剂,制备了纤维素乙醇木质素改性酚醛树脂胶黏剂,研究了木质素替代苯酚的工艺以及对胶黏剂性能的影响。研究发现:当木质素替代率为30%时,纤维素乙醇木质素改性酚醛树脂胶黏剂胶合强度达到国家Ⅰ类板要求,甲醛释放量达到Eo级,且成本低、胶合强度好、低毒环保,可广泛用于制备室外级人造板。     

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.     

Growth of Phlebiopsis gigantea in wood of seven conifer species

Heterobasidion parviporum and Heterobasidion annosum are widely distributed root‐rot fungi that infect conifers throughout Europe. Infection of conifer stumps by spores of these pathogens can be controlled by treating fresh stumps with a competing non‐pathogenic fungus, Phlebiopsis gigantea. In this study, growth of three Latvian strains of P. gigantea and the biological control agent ‘Rotstop’ strain was evaluated in stem pieces of Norway spruce, Scots pine, lodgepole pine, Douglas‐fir, Weymouth pine, Siberian larch and Sitka spruce. The growth rates of one H. parviporum and one H. annosum isolate were also measured in the same stem pieces. The growth rate of P. gigantea varied greatly in wood of different conifer species. It was higher in the three pine species, lower in Norway spruce and lowest in Sitka spruce and Siberian larch, and in Douglas‐fir, this fungus did not grow. The largest area of wood occupied by P. gigantea was in lodgepole pine. Growth of Latvian isolates of P. gigantea in the wood of Pinus and Picea species was comparable to that of the Rotstop isolate. Consequently, stump treatment with local P. gigantea isolates should be recommended. However, our results suggest that Douglas‐fir stump treatment against Heterobasidion by P. gigantea may be ineffective and other stump treatment methods should be considered.     

Decomposition and nutrient loss from prunings of different contour hedgerow species in tea plantations in the sloping highlands of Sri Lanka

Contour hedgerows of multipurpose tree species in the sloping tea lands of Sri Lanka are expected to reduce soil erosion and also add significant amounts of plant nutrients to the soil via periodic prunings. The objective of this experiment was to characterize the biomass decomposition pattern and quantify the amount of nutrients added through prunings of six tree species (Calliandra calothyrsus, Senna spectabilis, Euphatorium innulifolium, Flemingia congesta, Gliricidia sepium and Tithonia diversifolia) currently being used in hedgerows associated with tea. Withered leaf and stem prunings (50 g) were enclosed in 2-mm litter bags, placed at 5-cm depth and retrieved after one, three, six, nine and 12 weeks. Loss of initial dry weight, N, P and K was measured. Single exponential decay function adequately described both dry weight and nutrient loss. Tree species differed significantly in their rate of breakdown with decomposition constants (k) varying from 0.0299 to 0.2006 week⁻¹ for leaves and from 0.0225 to 0.0633 week⁻¹ for stems. Gliricidia showed the highest k for leaves with the rest in the following descending order: Senna > Tithonia ≥ Euphatorium > Calliandra > Flemingia. A similar pattern was observed for loss of all nutrients with Calliandra and Flemingia always having lower k values than the rest. Although N immobilization was not observed, immobilization of P and K was observed during the first week of incubation in some species, particularly in stem prunings. Annual biomass of prunings differed significantly between tree species in the following descending order: Calliandra > Senna > Flemingia > Tithonia > Gliricidia > Euphatorium. Calliandra added the greatest amount of nutrients annually to the soil with Euphatorium adding the least. Calliandra prunings provided the annual total K requirement and 49% of the N requirement of mature tea. However, none of the species provided more than 5% of the P requirement. It is concluded that among the tree species tested, Calliandra and Flemingia are the most suitable for contour hedgerows in tea plantations of this agroclimatic region because of their higher soil nutrient enrichment capacity and slower decomposition rates which would minimize leaching losses. This revised version was published online in June 2006 with corrections to the Cover Date.     

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。     

Effects of Seed Weight and Seed Type on Early Seedling Growth of Pinus sylvestris under Harsh and Optimal Conditions

The effects of seed weight and seed type on seedling growth of Pinus sylvestris (L.) were studied by seeding individually weighed orchard and stand seed in different mixtures under harsh (direct seeding in field) and optimal (seeding in nursery) conditions. In the nursery experiment an increase in the seed weight from 3 to 7 mg increased the seedling height by 10-27% and total weight by 27-113%, and decreased the height/diameter ratio by 5-6% after 2 yrs. With elimination of seed weight effects, orchard seedlings were 2% taller than stand seedlings in year 2. Without elimination of seed weight effects, orchard seedlings were 7-13% taller. In the field experiment an increase in the seed weight from 3 to 7 mg increased seedling height by 18-65%, stem volume by 81-274% and the number of top-buds by 23-34% in year 5. After elimination of seed weight effects, orchard seedlings were 7-13% taller than stand seedlings and without elimination of seed weight effects 20-21% taller after 5 yrs. Even after elimination of both seed weight and genetic effects orchard seedlings were 3-9% larger than stand seedlings in the field experiment. In conclusion, the influence of seed weight and seed type on growth traits and slenderness is highly significant and the influence seems to be greater in harsh conditions.     

Growth of Mixed Birch-Coniferous Stands in Relation to Pure Coniferous Stands at Similar Sites in South-eastern Norway

Mean age, mean and top heights and yield were studied in 20 mixed stands of birch ( Betula pubescens Ehrh. and B. pendula Roth) and Picea abies (L.) Karst. and nine mixed stands of birch and Pinus sylvestris L. in south-eastern Norway. Each mixed stand and the adjacent pure coniferous stand (control) were growing under the same site conditions and had not been commercially thinned. There were no significant differences in mean age at breast height or in top heights between birch and conifers in the mixed stands, while mean height was significantly higher for birch than for spruce. A growth index was calculated based on total volume and age at breast height. For the spruce sites the growth in young mixed stands (birch < 17 m) was superior to that of pure spruce, while the difference was insignificant in older stands. The growth index correlated positively with the ratio between generatively and vegetatively regenerated birch trees, and negatively with the age of the oldest species in the mixture and with site quality. For the pine sites there was no significant difference in the growth index between mixed birch-pine and pure pine stands. A mixture effect of birch on the volume yield of spruce or pine could not be demonstrated.     

Defoliation by the Needle-shortening Pine Gall Midge,Thecodiplosis brachyntera,on Pines in Central Sweden

An outbreak of the needle-shortening pine gall midge, Thecodiplosis brachyntera , occurred on Scots pine, Pinus sylvestris (L.) and lodgepole pine, P. contorta (Dougl.) in central Sweden during 1995-1998. The larval feeding of T. brachyntera kills current-year needles and heavy infestation causes severe defoliation. A pattern of fluctuating defoliation among years and sites was found on both pine species. Defoliation was evenly distributed in the crown of P. sylvestris during years of high as well as low infestation; apical whorls had as much defoliation as basal whorls. In P. contorta , however, there was a tendency for defoliation to be concentrated on branches in the most apical whorls. Growth ring increments on P. sylvestris with high levels of defoliation (71%) did not differ from trees with moderate levels (26%) of defoliation. Shoot lengths were significantly shorter, however, on heavily infested trees the year after defoliation.