甲苯二异氰酸酯交联聚乙烯醇木材粘合剂

用正交实验法,研究在水基中和催化剂-X存在下,甲苯二异氰酸酯(TDI)交联聚乙烯醇(PVA)的反应。探讨PVA、交联剂TDI和催化剂-X的加入量、交联反应的温度,以及交联反应进行的时间等因素对该粘合剂压缩剪切强度和颜色稳定性的影响。研究结果表明,本实验交联改性PVA胶水的方法,较大程度地提高粘胶的粘结性能;在实验条件范围内,粘胶的颜色稳定性只与交联反应的温度有关,而与其他实验条件无关。本研究形成一种白色的乳胶,对环境和人体健康无影响,适合于木材加工业,尤其是室内装饰用木材的粘结。本研究中试产品,经质量检验,合乎化工行业标准。     

三苯基甲烷三异氰酸酯交联聚乙烯醇木材粘合剂的研究

采用正交实验法，探究在水基中三苯基甲烷—4，4′，4″—三异氰酸菌(TTI)交联聚乙烯醇(PVA)的反应。TTI是直接用列克纳胶(JQ—1)为原料，利用其与PVA交联反应产物的不溶性和体系的压缩剪切强度等性能判断该反应的进程。结果表明，TTI的加入较大幅度地提高PVA胶水的粘结性能和耐水性能，尤其突出的是颜色为稳定的乳白色。     

TDI交联PVA乳液生产柔性集成材刨切薄木的研究

对采用TDI交联PVA乳液胶粘剂制造的柔性集成材刨切薄木进行研究,结果表明,该制品具有良好的柔韧性和胶合性能;因TDI交联PVA乳液胶粘剂自身不含甲醛等有害物质,且价格低廉,用其生产出的柔性集成材刨切薄木成本低,环保性能优良。     

甲苯二异氰酸酯改性PVA和HEC混合乳胶的研究

研究了在水介质中采用少量甲苯二异氰酸酯(TDI)对HEC和PVA混合胶水进行交联改性,合成了一种新型单组份亮白色的乳胶。采用正交实验,以压缩剪切强度为主要考察指标,优选出制备改性PVA和HEC混合乳胶最佳工艺条件为:PVA加入量为8.0 g/100 mL、HEC加入量为4.0 g/100 mL、TDI加入量为3.0 mL/100 mL、反应温度为60℃、反应时间为90min,催化剂-D加入量为2.0 mL/100 mL。该条件下合成的乳胶压缩剪切强度可达到7.19 MPa。     

硼砂和羟乙基纤维素改性TDI交联聚乙烯醇木材粘合剂的研究

笔者主要研究以硼砂和羟乙基纤维素改进甲苯二异氰酸酯(TDI)交联聚乙烯醇(PVA)木材粘合剂。采用正交试验法,探讨实验室制备该粘合剂的工艺条件:如羟乙基纤维素(HEC)、PVA、硼砂、交联剂TDI的加入量、合成反应的温度以及合成反应的时间等因素对该粘合剂粘结性能(包括压缩剪切强度、融冻性、颜色、黏度等)的影响。通过该改性过程能形成一种稳定的单组分、性能优良、原料成本合理、无环境污染的白色木材乳胶。通过正交试验分析得出在该试验设计范围内实验室制备该木材粘合剂最佳合成工艺:硼砂的加入量为0.1g/100 mL、HEC的加入量为0.4g/100 mL、PVA的加入量为10g/100mL、TDI的加入量为3mL/100mL、反应温度为30℃,搅拌反应时间为75min。聚乙烯醇粘合剂通过该改性过程,其压缩剪切强度达到6MPa以上,能形成一种稳定的单组分、性能优良、原料成本合理、无环境污染的白色木材乳胶。     

PVA交联处理对硅酸钠胶黏剂性能的影响

采用聚乙烯醇(PVA)与硅酸钠进行交联处理,以改善硅酸钠胶黏剂的胶接强度和耐水性能。研究了PVA交联反应温度、时间和p H值对硅酸钠胶黏剂胶接强度和耐水性能的影响,并采用傅立叶变换红外光谱(FT-IR)研究交联改性提高胶接强度和耐水性能的机制。结果表明:交联温度为80℃,交联时间为90 min,p H值为9时,PVA交联硅酸钠胶黏剂的胶接强度和耐水性能最佳;FT-IR分析显示PVA和硅酸钠成功发生交联,并促进硅酸钠胶黏剂的固化,从而使胶接强度和耐水性能得到提高。     

TTI交联聚乙烯醇木材胶黏剂的研究

研究在水基中三苯基甲烷-4,4',4"-三异氰酸酯(TTI)交联聚乙烯醇(PVA)所形成的白色乳胶。采用正交试验法探讨聚乙烯醇、催化剂-x、TTI的加入量、反应时间及反应温度对该乳胶性能的影响。合成的单组份环保乳胶适用于木材、纸品等加工业,以及建筑业。     

二羟甲基丙酸前景看好

目前，我国市场上的涂料、胶粘剂、皮革涂饰剂等化工产品，多为溶剂型。其中有机溶剂，不仅有刺鼻的气味、易燃，且对人体健康极为不利。故发达国家已对此实行禁用、限用，改进为水基性的高聚物。而二羟甲基丙酸（ＤＭＰＡ）是生产无环境污染的水基性高聚物如水基涂料、粘胶剂、皮革涂饰剂、树脂等许多化工产品的主要基础材料，其市场前景十分广阔。二羟甲基丙酸具有羟基和羟基多功能反应，还具有类似于金刚石结构的热和光的稳定性，作为交联、固化分散、乳化剂厂广泛用于水基高聚物的生产中，其产品具有优越性能。如用它制备的涂料不仅无环…     

在聚乙烯醇胶水体系中TDI与水反应的平均速率的研究

聚乙烯醇(PVA)是一种多羟基的高分子化合物,它的突出优点是水溶性、无毒无害、原料易得,因而得到广泛应用。尤其是在环保型粘合剂方面,其研究意义非常突出。PVA 水溶液作为粘合剂,其胶膜耐水性差,在要求较高时 PVA 胶水的粘结强度不够。通常的改进方法是利用 PVA 链上-OH 基团发生化学反应,比如:与醛缩合;与热固性树脂脱水交联;与双官能团化合物二羟基甲基脲、乙二醛、乙二酸等进行交联反应;加入交联剂硼砂、硼酸、硫酸盐等。例如与甲醛缩合,用作建筑胶水,性能改进不够理想,特     

松节油衍生物（艹孟）二胺的性质及其应用研究进展

（艹孟）二胺是重要的松节油深加工产品，与水合萜二醇有相同的骨架结构。本文综述了国内外有关（艹孟）二胺的物理特性及其在作为环氧树脂固化剂、香皂配方中的细菌抑制剂、聚酰胺树脂、聚氨酯、硅醇缩合催化剂、提高聚烯烃织物纤维染色能力共聚物的原料和一些反应中的助剂等方面应用的研究进展。     

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.