表面处理对改善装饰原纸印刷适性的研究

采用淀粉和苯乙烯丙烯酸酯乳液复配,对装饰原纸进行表面处理。研究了表面处理工艺对装饰原纸抗张强度、表面性能和印刷适性的影响。结果表明:当淀粉和苯乙烯丙烯酸酯乳液以质量比20︰1进行复配时,装饰原纸表面处理后的抗张强度和平滑度大幅提高;印刷后色密度提高,阶调再现性增大,吸收性没有损失。印刷性能显示三聚氰胺浸渍处理能使印刷图案保留时间更久。     

纤维板防水剂用石蜡-松香乳液的组成及其性能研究

采用专用高分子表面活性剂和转相法制备了系列石蜡-松香乳液,并考察了这些乳液中的表面活性剂种类和石蜡与松香的质量比对中密度纤维板防水性和力学性能的影响。研究结果表明,用苯乙烯和丙烯酸及其衍生物为单体的高分子表面活性剂(HS)和烷基苯聚氧化乙烯醚衍生物的低分子表面活性剂(LS)的混合物能制得稳定的石蜡-松香乳液。表面活性剂用量为5kg／m^3时石蜡-松香(质量比1：2)乳液使纤维板的吸水厚度膨胀率减少23．8％,而弹性模量增加了12．2％。表面活性剂的组成和石蜡与松香的质量比都显著地影响乳液的性能和使用效果。     

涂料涂布对人造板装饰原纸表面性状和印刷适性的影响及其机制

【目的】结合装饰原纸抄造和涂布整饰工艺,研究颜料化涂布改善装饰原纸印刷适性的作用机制,为装饰原纸的性能改善及其在人造板装饰领域的运用提供参考依据。【方法】优选阔叶木浆和针叶木浆,辅以二氧化钛、聚丙烯酰胺(PAM)、聚酰胺环氧氯丙烷(PAE)、硫酸铝等填料和助剂,通过动态纸页成型器抄造装饰原纸;以聚乙烯醇(PVA)、阳离子淀粉为胶黏剂,添加蒸馏水、颜料、分散剂等助剂,在高速搅拌机中搅拌40~60 min,制备涂料,通过激光粒度仪、锥板黏度计分析涂料的粒径和触变性;采用涂布机和压光机对所制装饰原纸进行涂布和压光整饰,利用SEM、AFM、动态渗透分析仪、动态接触角测定仪对涂布装饰原纸的涂层形貌结构进行表征分析;采用印刷适性仪对涂布装饰原纸进行凹版印刷打样,通过色密度计测量样张的颜色特性,分析涂布装饰原纸的印刷性能。【结果】通过粒径和触变性分析得出,Ti O2(201)和Si O2颜料粒径小且分布窄,Ti O2(902)和Clay颜料粒径大且分布宽,而Al2O3颜料粒径小且分布宽,颜料制备成涂料后涂料粒径分布范围均变大,其中Clay涂料粒径分布范围最大,Si O2涂料粒径分布范围最小;Clay涂料和Al2O3涂料的触变性大,Ti O2(902)涂料和Si O2涂料触变性小;涂层结构性能研究发现,Si O2涂层能更有效覆盖原纸表面,且孔隙分布均匀;Si O2涂层在1.3 s内动态接触角下降幅度达58.17%,且动态渗透Ci最小为17.6,Ct为2.8,表明Si O2涂布装饰原纸表面的孔隙小且更加紧密,易形成良好的均匀紧密涂层结构;在涂布装饰原纸物理性能改善方面,紧度提高25%~61%,吸水高度提高33%~118%,平滑度提高150%~290%,干抗张强度提高171%~194%,湿抗张强度提高220%~290%,其中Si O2涂料涂布装饰原纸的综合物理性能最优,紧度提高25%,吸水高度提高108%,平滑度提高290%,干抗张强度提高171%,湿抗张强度提高290%;在印刷性能方面,Si O2涂布装饰原纸在凹印网穴深度为33μm时,其印品的青品黄三色密度分别达到1.31、1.3和1.28,比原纸色密度提高16.5%~40%,颜色整体阶调再现范围变大,印刷装饰效果更加优异。【结论】对装饰原纸进行Si O2涂料涂布,能够有效填充装饰原纸表面孔隙,形成优良的涂层结构,有助于印刷油墨的吸收固着,从而抑制网点扩大进而起到有效改善原纸印刷适性作用。     

聚氨酯-丙烯酸酯-环氧大豆油复合乳液的合成与性能

采用环氧大豆油(ESO)、甲基丙烯酸甲酯(MMA)、丙烯酸丁酯(BA)、丙烯酸-2-羟丙酯(HPA)改性水性聚氨酯,制得以丙烯酸酯为核、聚氨酯为壳的核壳结构聚氨酯-丙烯酸酯-环氧大豆油复合乳液.用红外光谱仪(FT-IR)、马尔文粒度分析仪等测试手段对合成产物进行了结构和性能的表征.考察了工艺参数对聚合过程的影响,以及ESO和MMA用量对复合乳液及其胶膜性能的影响.结果表明,较佳的工艺条件为预聚温度80℃,时间1.5 h;扩链温度70℃,时间4～5h;中和温度40℃,加水乳化分散时间为10 min,转速为6000 r/min;乳液聚合温度70℃,时间为4～5 h;当ESO用量为4%～6%、甲基丙烯酸甲酯用量为30%时,可制得粒径较小贮存稳定性好的聚氨酯-丙烯酸酯-环氧大豆油复合乳液,该复合乳液的胶膜耐介质性好、吸水率低.     

丙烯酸酯/石蜡共混乳液处理材疏水性研究

针对石蜡和丙烯酸(酯)在木材防水改良应用方面的优势和不足,提出了利用丙烯酸酯乳液共混改性石蜡乳液。探究丙烯酸酯乳液对复合乳液成膜性及其对复合乳液处理材疏水性能的影响。考察了复合乳液粒径、离心稳定性、成膜性以及处理材吸水率、表面润湿性和尺寸稳定性等。研究结果表明:1)复合乳液可被用于木材浸渍改性处理,复合乳液平均粒径约180.0 nm。2)相比于石蜡乳液处理,复合乳液中丙烯酸酯乳液可协助石蜡在处理材内部形成有效疏水膜层,提高木材疏水性和尺寸稳定性。     

枫香树脂/丙烯酸酯复合乳液及其压敏胶的性能

以混合丙烯酸酯为共聚单体,枫香树脂为增粘剂,过硫酸铵(APS)为引发剂,十二烷基硫酸钠(SDS)、烷基酚聚氧乙烯醚(OP-10)为乳化剂,采用预乳化半连续乳液聚合法制备枫香树脂-丙烯酸酯复合乳液。研究枫香树脂用量对单体转化率、凝胶率、玻璃化转变温度、热稳定性以及压敏胶(PSA)粘接性能的影响。结果表明,在枫香树脂一定的质量分数范围内,随着枫香树脂用量的增加,分子量、凝胶率、热稳定性、玻璃化转变温度随之增加。枫香树脂的适宜用量为质量分数10.0%,此时压敏胶的初粘力为16#,180°剥离强度为10.12 N·25 mm-1。     

丙烯酸异冰片酯改性水性聚氨酯的合成及其表征

通过乳液聚合法制备了丙烯酸异冰片酯(IBOA)改性水性聚氨酯(WPU)复合乳液,考察了引发剂用量、反应温度、IBOA/WPU质量比及保温时间对单体转化率、胶膜吸水率及拉伸强度的影响,同时采用正交试验对工艺条件进行了优化。研究结果表明,较适宜的反应条件为IBOA与WPU固体组分质量比为1∶3,引发剂过硫酸铵(APS)用量为IBOA单体添加量的0.5%,反应温度80℃,保温熟化3 h。利用傅立叶变换红外光谱、透射电子显微镜、热重分析等测试方法对复合材料的性能进行了表征,并探讨了性能与结构的关系,结果显示单体的平均转化率达97.35%,改性水性聚氨酯的吸水率达到5.94%,拉伸强度达到27.17 MPa。制备的乳液为核壳结构,乳液稳定性良好;胶膜发生的热降解分别由硬段降解和软段降解造成。     

利用生物质硅源改性丙烯酸酯水性涂料研究

以稻壳为生物质硅源,通过酸浸、煅烧的方式制取二氧化硅(Si O2),用γ-甲基丙烯酰氧基丙基三甲氧基硅烷(KH570)表面改性后作为增强填料,制备了水性丙烯酸酯-二氧化硅有机-无机杂化乳液,以期改善水性丙烯酸木器涂料的耐磨性、硬度等,最终合成出理化性能优异的水性丙烯酸木器涂料。利用扫描电子显微镜(SEM)、透射电子显微镜(TEM)、傅里叶变换红外光谱(FT-IR)、X射线衍射(XRD)等手段对稻壳灰、改性二氧化硅的表面形貌、官能团变化、聚集态等方面进行了表征,同时对比了改性前后漆膜的力学性能、热失重性能和硬度。结果表明:650℃煅烧得到稻壳灰呈现出非晶无定形态结构;二氧化硅表面经硅烷偶联剂KH-570改性后成功地连接到其表面上,并呈微纳米级分散在水性丙烯酸酯涂料体系中;聚丙烯酸酯乳液粒径主要分布在89～95 nm之间;二氧化硅添加量为2%质量分数时,涂膜的断裂伸长率为303.06%,拉伸强度48.673 MPa,弹性模量达6.672 MPa,漆膜硬度2H,涂膜力学性能最优。综合比较第1组(A4)丙烯酸单体配比填加2%和3%质量分数的稻壳灰(RHA)漆膜磨耗较小,光泽度均在50左右。随着二氧化硅添加量的增加,附着力提高至0级。利用稻壳提取二氧化硅改性水性丙烯酸木器涂料,其综合性能具有一定程度的提高,为稻壳的增值化利用提供了一个可行的途径。     

阳离子聚合物施胶增效剂的制备与应用

以丙烯酸甲酯、苯乙烯和阳离子单体为主要原料,采用无皂聚合法制备了阳离子聚丙烯酸酯乳液(CPEE),优化的制备工艺为：阳离子单体用量为总单体量的5％,引发剂用量为总单体量的1％。CPEE、阳离子聚酰胺多胺环氧氯丙烷(PAE)和阳离子淀粉(CS)作为施胶增效剂,用于阳离子石油树脂胶在草浆中的施胶,能够实现中性施胶并取得较好的施胶效果。CPEE和PAE配合使用可明显提高纸页的施胶度和裂断长,效果优于普通的助留剂。     

萜烯树脂乳液的研制

采用专用高分子表面活性剂研制了系列萜烯树脂乳液.研究结果表明,修正后的计算亲水亲油平衡值(HLB值)的方法可用于高分子表面活性剂中单体质量比的设计,萜烯树脂的HLB值被定为13.乳化中应添加助溶剂来降低萜烯树脂的熔化温度和时间.高分子表面活性剂的结构极大地影响萜烯树脂的乳化结果,本研究中高分子表面活性剂苯乙烯-聚丙烯酰胺-单体3(质量比1:0.6:0.2)用量为10%时能将萜烯树脂T-90、T-100和T-110乳化成稳定的乳液.     

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.     

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.     

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.     

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。     

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.