木质素磺酸钠脱磺及应用性能研究

以亚硫酸盐法制浆的副产品木质素磺酸钠为原料,采用均匀设计法深入探讨蒸煮温度、蒸煮时间、氢氧化钠用量等反应条件对木质素磺酸盐脱磺的影响.结果表明,最佳脱磺条件为:蒸煮温度180℃,蒸煮时间3h,氢氧化钠用量7%;经红外光谱、凝胶色谱、差热和流变特性分析,脱磺后分离纯化的木质素具有较好的玻璃化、热塑性能和熔融塑化性能,为热塑性木质素的开发利用提供了一定的理论依据.     

竹子高沸醇溶剂法制备纸浆纤维与木质素的研究

以竹子为原料，在70％～90％的1，4-丁二醇水溶液中添加少量助剂，并在180～200℃条件下反应30～90min，制备得到竹子纸浆纤维和高沸醇木质素高沸醇溶剂(HBS)法制得的竹子纤维经进一步改性可用于造纸或加工成其他纤维素产品，高沸醇木质素较好地保持了木质素的化学活性，灰分含量低于小质素磺酸盐，在材料科学与工程领域有潜在的应用前景。高沸醇溶剂1，4-丁二醇经回收处理可以循环使用。     

亚硫酸氢镁预处理麦秆木质素磺酸盐的性质和应用

木质纤维原料是一种丰富的可再生资源,其中木质素分子结构最为复杂,木质素的综合利用度成为木质纤维原料生物炼制商业化的瓶颈和关键。当前,我国商品木质素磺酸盐主要来源于亚硫酸盐制浆造纸废液,而源于生物炼制的木质素磺酸盐材料的研究和应用却鲜有报道。我国是农业大国,麦秆资源丰富,笔者对亚硫酸氢镁预处理麦秆木质素磺酸盐进行了性质和应用初步研究。结果表明:与市售商用木质素磺酸盐(CMLS)相比较,麦秆木质素磺酸盐(IELS)磺酸基团较高,酚羟基和羧基含量较低;重均分子量和数均分子量分别为3 456 u和2 842 u,分子量分布均一;对于微晶纤维素的酶解有促进作用,添加1.0 g/L IELS,酶解48 h纤维素酶解得率达72.3%,较空白组提高了7.7%;添加质量浓度2.0 g/L的超滤麦秆木质素磺酸盐(UFLS)可使甲基咪草烟(IMM)颗粒表面Zeta电位降至-30.3 mV;质量浓度2.0 g/L的UFLS液滴在IMM压片表面接触角为72.38°,易于在疏水材料上铺展开来。研究结果可为生物炼制来源木质素磺酸盐的资源化高效利用提供理论参考。     

工业木质素的开发利用

1　工业木质素的性能与用途植物纤维原料在制浆过程中降解溶出的木质素称为工业木质素。根据化学制浆方法的不同 ,工业木质素分为结构和性能完全不同的碱木质素 (碱法制浆溶出的木质素 ,包括烧碱木质素和硫酸盐木质素 )和木质素磺酸盐 (亚硫酸盐法制浆煮溶出的木质素 )两类。碱木质素的分子量较低 ,水溶性差 ,很多场合不能直接使用。碱木质素经适当改性后 ,可用作染料分散剂、橡胶添加剂、水泥减水剂等。木质素磺酸盐的分子量达数万至上百万 ,具有良好的水溶性 ,其分子结构包括疏水性的芳环和亲水性的磺酸基 ,具有一定的表面活性。工业木质…     

木质素磺酸盐与丙烯酸类单体的接枝共聚研究

研究了木质素磺酸盐粗产品与丙烯酸类单体的接枝共聚反应，对其反应机理进行了评述，并采用红外光谱分析证实了聚合反应的发生。与现有的对纯化木质素磺酸盐的研究结果不同，粗产品的接枝共聚反应可以单纯由过氧化氢引发，原因可能是粗产品中含有的还原性物质起到了亚铁离子的作用。研究表明，合适的引发剂用量应该是木质素磺酸盐干重的1．5％～2．0％，当反应体系中引发剂用量充分时，反应温度和时间对产物粘度的影响不明显。产物的粘度随丙烯酸类单体用量的增加而提高，在相同单体用量下，丙烯酰胺改性产物的粘度高于丙烯酸改性产物，原因是丙烯酰胺聚合物上酰胺基的亲水性比丙烯酸聚合物上羧酸基的亲水性低。     

超滤膜分级对木质素磺酸盐作为抑尘剂性能的影响

采用截留分子质量为6 000和20 000 u的两种超滤膜对木质素磺酸盐进行过滤分级,获得3种不同分子质量木质素磺酸盐级分(LG-1、LG-2和LG-3),分析了各级分的得率、纯度、分子质量及亲水基团含量,并考察了各级分作为抑尘剂的性能差异。结果表明:通过超滤膜过滤可以对木质素磺酸盐进行有效分级,LG-1、LG-2和LG-3的得率分别为58.32%、24.50%和17.18%,重均相对分子质量分别为4 841,15 239和37 768,分散度(M_w/M_n)分别为2.78、2.40和2.06。随着木质素磺酸盐级分相对分子质量增加,灰分含量降低,总糖含量增加;同时磺酸基团含量降低。超滤膜分级对木质素磺酸盐作为抑尘剂的性能具有显著的影响,随着截留分子质量的增加,木质素磺酸盐吸湿能力、抗压及抗风蚀能力都有所提高,分别提高了96.43%、55.11%和63.07%,表明高分子质量木质素磺酸盐级分(LG-3)作为抑尘剂表现出更好的性能。SEM分析表明,喷洒木质素磺酸盐溶液后,沙粒之间有粘结层,表现出一定的粘结性和结壳性,且截留分子质量越大粘结现象越明显。     

木质素对H3PO4法活性炭孔隙结构的影响

以杨木、落叶松木、麻秆屑为原料,采用乙酸-亚氯酸钠法对原料进行脱木质素处理,研究木质素对H3PO4法活性炭孔隙结构的影响.通过物理吸附仪测定活性炭的比表面积和孔结构,利用碘值和亚甲基蓝吸附分析其吸附性能;采用TG/DTG分析原料去除木质素前后热解过程.结果表明,除去木质素后活性炭的比表面积、总孔容、外表面积变小;微孔孔...     

棉秆与麦草蒸煮反应的动力学比较

比较了棉秆和麦草蒸煮反应的脱木质素速率常数,提出一种研究蒸煮反应动力学的实验和计算新方法。通过对不同恒温条件下的反应速率常数计算,采用与实际蒸煮反应相同的液比,用较短时间周期的有效碱浓度变化值和木质素含量变化值计算得出了两种原料烧碱-蒽醌法蒸煮反应的活化能。棉秆烧碱-蒽醌法蒸煮反应的活化能和麦草烧碱-蒽醌法蒸煮反应的活化能在整个脱木质素阶段基本是不变的。麦草烧碱-蒽醌蒸煮反应的活化能为51.0 kJ/mol。棉秆烧碱-蒽醌法蒸煮反应的活化能是138.1 kJ/mol,高于麦草蒸煮反应活化能,说明麦草蒸煮脱木质素反应比棉秆更容易。     

马尾松硫酸盐浆两段氧脱木质素最佳工艺条件的研究

研究了马尾松硫酸浆两段氧脱木质素的最佳工艺条件。结果表明，第一段氧脱木质素的条件为：氧压0．6MPa，温度100℃，时间80min,NaOH 量5％，MgSO4用量0．5％，浆浓10％；第二段氧脱木质素的条件为：氧压0．4MPa，温度90℃，时间60min，NaOH用量3％，MgSO4用量0．5％，浆浓10％。在此条件下，OIOⅡ木质素脱除率达到72．5％，粘度775．2cm^3/g,得率90．5％。经过氧脱木质素后浆的裂断长5．8km，耐破指数5．3kPa.m^2/g，撕裂指数12．7mN.m^2/g。     

813钻井泥浆稀释剂的研制与应用

本文介绍了以处理过的橡椀为原料,经抽出、磺化、络合……等加工而制成的一种石油、地质钻井泥浆处理剂——813稀释剂。先后试制了几批,证明工艺可行,操作方便,制品质量稳定。其化学组成与国内外铁铬木质素磺酸盐的红外光谱比较,几个主要基团的强吸收峰都极为近似。三年来,经中原油田试用了179吨,效果良好,抗盐、抗温性能均优于栲胶、磺甲基栲胶,与铁铬木质素磺酸盐相当。本品在稀释的同时有一定的降失水作用,可节省CMC用量;从而提高了钻井效率,降低泥浆成本,经济效益显著。     

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.     

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.     

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。