聚合松香基环氧树脂的合成与表征

以聚合松香为原料,与环氧氯丙烷进行酯化反应、闭环反应,合成了聚合松香基环氧树脂,并对产物的红外光谱和核磁共振谱进行了解析.重点讨论了酯化反应、闭环反应影响因素对产物性能的影响.当适宜的反应条件为:聚合松香与环氧氯丙烷物质的量比约为1∶ 8,反应温度75℃,反应总时间8h,合成的环氧树脂的环氧值为0.19mol/100g,黏度(30℃)为30.8Pa · s,酸值为0.2mg/g.     

二聚脂肪酸混合物合成环氧树脂研究

通过丙烯海松酸(APA)和二聚脂肪酸(DA)按一定比例混合,与环氧氯丙烷(ECH)进行酯化反应、闭环反应,合成了APA与DA复合环氧树脂.重点研究了酯化阶段反应温度、反应时间及催化剂用量等影响因素;闭环阶段反应温度、碱的形态及ECH用量对闭环反应的影响.在适宜的合成条件和配比下,每100 g环氧树脂环氧值为 0.26 eq,粘度(40 ℃)为530 mPa·s,酸值为0.3 mg/g.对原料与产物环氧树脂红外光谱进行了分析对比.     

丙烯酸改性松香基环氧树脂的合成研究

以松香为基本原料 ,通过D A加成反应 ,合成了丙烯酸改性松香 ,继而与环氧氯丙烷进行酯化反应、闭环反应 ,合成了丙烯酸改性松香基环氧树脂。本文重点讨论了反应温度、反应时间及催化剂用量等因素对酯化反应的影响 ;闭环温度、碱的体积分数及溶剂的种类对闭环反应的影响。在适宜的合成条件下合成环氧树脂的环氧值为 0 .2 7eq/1 0 0 g,粘度 (4 0℃ )为 2 5 .2 5Pa·s,酸值为 0 .4mgKOH/g。并对产物的红外光谱进行了解析。     

蓖麻油缩水甘油醚合成工艺研究

以蓖麻油、环氧氯丙烷(ECH)和液碱为主要原料,经二步法开环闭环反应合成了蓖麻油缩水甘油醚(COGE),研究了开环、闭环工艺条件对产物环氧值的影响。结果表明,开环催化剂三氟化硼-二乙基醚用量0.4%,ECH与蓖麻油的物质的量比3.5∶1,反应温度60℃,反应时间5 h;闭环催化剂四甲基氯化铵用量0.4%,反应时间6 h,反应温度60℃,Na OH与ECH物质的量比1.1∶1时产物环氧值最高为1.56 mmol/g。采用红外光谱(FT-IR)、核磁共振氢谱(1H NMR)表征了合成产物的化学结构,热失重(TG)分析表明蓖麻油缩水甘油醚具有优良的高温热稳定性,黏度测试表明该产物可以降低环氧树脂的黏度,加入量15%时,黏度降低46%。     

氢化萜烯马来酸酐合成环氧树脂的研究

以氢化萜烯马来酸酐(HTMA)为原料与环氧氯丙烷反应合成一种含桥环结构的饱和脂环基环氧树脂--氢化萜烯酯型环氧树脂(HTME).通过研究反应物料配比、反应温度与时间、催化剂用量、碱的用量与浓度以及溶剂类型等因素对合成反应的影响,确定了最佳合成反应条件,并经FT-IR及NMR光谱表征了环氧树脂的化学结构.该树脂为浅黄色透明液体,采用化学分析方法测定其环氧值3.5～3.9 mmol/g,黏度 1.7 Pa·s(50 ℃),酸值＜0.5 mg/g.     

没食子酸改性氢化萜烯基环氧树脂多元醇的合成及性能研究

利用天然可再生资源没食子酸(GA)与氢化萜烯基环氧树脂(HTME)在一定条件下反应制备了环氧树脂基多元醇(HTME - GA多元醇).通过研究合成反应的影响因素,确定了HTME - GA多元醇的合成反应条件:以GA物质的量12.5倍的正丙醇为反应溶剂,以占HTME与GA总质量2%的季铵盐为催化剂,HTME与GA共沸回流反应3h.经FT - IR、NMR光谱表征了HTME - GA多元醇的化学结构,比较了该多元醇与聚己二异氰酸酯HN90T、改性聚己二异氰酸酯EC385的交联反应特性及交联产物性能.实验结果表明,HTME - GA多元醇与EC385的交联产物具有优良的机械力学性能,与HN90T的交联产物具有较好的耐液体介质性能和硬度,但后者柔韧性较差.随着NCO与OH物质的量比的增大,交联产物的硬度和耐液体介质性能提高.     

Synthesis of 2,3,4,4'-tetrahydroxybenzophenone via Hoesch Reaction

提出了一种新颖的合成2,3,4,4-四羟基二苯甲酮的方法.以焦性没食子酸和对羟基苯甲腈为原料,于无水乙醚中在氯化氢和Lewis酸ZnCl2存在下发生Hoesch反应,经后处理得到2,3,4.4-四羟基二苯甲酮.通过正交试验对影响反应的因素进行了考察,确定了最优工艺条件:焦性没食子酸与对羟基苯甲腈的物质的量比为1∶0.96,催化剂54.4 g(相对于1 mol焦性没食子酸),反应温度20℃,反应时间24h.在此条件下产品得率达90％以上,产品纯度在98％以上.     

萜烯基环碳酸酯的合成及其表征

在苄基三乙基氯化铵-乙二醇共催化作用下,以萜烯基环氧树脂为原料,与CO2在无溶剂环境中反应合成了萜烯基环碳酸酯.研究了催化剂用量、CO2压力、反应温度以及反应时间对反应过程的影响,并采用电位滴定法测定了产物中环碳酸酯的含量.研究表明,在催化剂用量1.0％、CO2压力1.0 MPa条件下,130℃反应7h,生成产物的环碳酸酯值为0.267,环氧基转化率达99.7％,环碳酸酯选择性达到94.0％.同时,采用凝胶渗透色谱(GPC)、红外光谱(FT-IR)、质谱(MS)、核磁共振氢谱(1H NMR)及碳谱(13C NMR)表征了合成产物的化学结构.     

Hoesch反应法合成2,3,4,4'-四羟基二苯甲酮的研究

提出了一种新颖的合成2,3,4,4’-四羟基二苯甲酮的方法。以焦性没食子酸和对羟基苯甲腈为原料,于无水乙醚中在氯化氢和Lewis酸ZnCl2存在下发生Hoesch反应,经后处理得到2,3,4,4’-四羟基二苯甲酮。通过正交试验对影响反应的因素进行了考察,确定了最优工艺条件:焦性没食子酸与对羟基苯甲腈的物质的量比为1∶0.96,催化剂54.4 g(相对于1 mol焦性没食子酸),反应温度20℃,反应时间24 h。在此条件下产品得率达90%以上,产品纯度在98%以上。     

氢化萜烯酯型环氧树脂固化反应表征与机械性能研究

氢化萜烯酯型环氧树脂(HTME)是以萜烯-马来酸酐加成物的氢化产物与环氧氯丙烷反应合成的环氧树脂。通过DSC热分析、凝胶时间的测定及其影响因素分析,研究了HTME与甲基六氢苯酐(MeHHPA)的固化反应活性;通过FT-IR光谱法定性分析与固化度测定法定量分析,表征了HTME/MeHHPA体系的固化反应行为及完成固化反应的条件;并比较了HTME、TME及环氧树脂6101与Me-HHPA固化产物的机械性能。结果表明,HTME/M eHHPA体系的固化反应属于放热反应,反应热焓为153.5 J/g,峰顶温度为157.9℃;在0.5?MA促进剂条件下,110℃经8 h可完全固化,且HTME与MeHHPA按化学计量配比时固化效果最好,固化产物的机械性能与环氧树脂6101固化物的性能相似。     

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.     

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.     

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.     

Potential to harness superior nutritional qualities of exotic baobabs if local adaptation can be conferred through grafting

Baobab leaves form an important part of the local diet in Sahel countries and elsewhere in Africa. Existing leaf nutritional data and agroforestry performance information are based solely on Adansonia digitata L., the baobab of continental Africa. The introduction potential of Adansonia species from the center of diversity in Madagascar and from Australia remains untapped. To assess this potential, the mineral contents and B₁ and B₂ vitamin levels of dried baobab leaves were determined for five-year old trees of A. digitata, A. gibbosa (A. Cunn.) Guymer ex D. Baum, A. rubrostipa Jum. & H. Perrier (syn. A. fony Baill.), A. perrieri Capuron and A. za Baill. grown in an introduction trial in Mali. Nutritional data were evaluated against survival and vigor to identify promising germplasm. Leaf vitamin and crude protein contents were highest in the Madagascar species, especially A. rubrostipa (B₁ 88 mg 100 g⁻¹, B₂ 187 mg 100 g⁻¹, protein 20.7% dry weight). However, the local species far outperformed the introductions in survival, tree height, basal diameter and resistance to termites. We suggest grafting as a way of harnessing the vigor of well-adapted local baobab varieties to the superior nutritional profiles of A. rubrostipa and others. Cross-species grafting tests in Adansonia were successful, thus creating new agroforestry possibilities with different scion/rootstock combinations.     

Modelling of adequate pretwist for obtaining straight timber

Abstract

Wood in general and wooden studs in particular are often distorted owing to uneven shrinkage during the drying process in the sawmill. Twist is often the most detrimental of all types of distortion, and it is caused by spiral grain in combination with variations in moisture content. For sawmills, the objective is to produce dried, straight boards, and one method of dealing with boards with excessive spiral grain is to sort them out and then dry them in a pretwisted position to obtain straight boards after drying. A model using the finite element (FE) method for the simulation of drying twist distortions was first calibrated against laboratory experiments in which boards were dried with and without restraints and pretwists. After the calibration, the FE results were compared with industrial test results for boards that were dried without restraints or with restraints with zero pretwist, i.e. straight restraints. The FE model used an elastic–ideally plastic material model to obtain permanent deformations. The calibration was to set the yield stresses so that there was a good match between FE results and results from the laboratory experiments. The comparison between the industrial test results and the FE results showed that the FE model is capable of realistic simulations of drying boards with and without restraints and presumably also pretwists.     

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。     

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.