工艺参数对稻壳-木刨花复合板内结合强度的影响

采用均匀实验设计方法,通过单因素及两因素间交互作用情况,探讨工艺参数对稻壳-木刨花复合板内结合强度(IB)的影响。在试验研究范围内,密度、芯层比例、芯层施胶量、热压温度、热压时间对复合板IB影响显著,表现为IB随密度的增大先增大后减小,随芯层比例和芯层施胶量的增加而增加,随热压温度和热压时间的增加而减小。当密度为0.77 g/cm3、芯层比例为60%~65%、芯层施胶量为4.5%、热压温度为170℃、热压压力为2.5 MPa、热压时间为20 s/mm时,在兼顾生产效率与生产成本的同时,能够获得IB良好的稻壳-木刨花复合板。     

生态木竹纤维复合装饰板材成型工艺

天然纤维复合材料是国内外近年蓬勃兴起的一类新型绿色复合材料。本文研发了一种用于家具及室内装饰的多层复合板,其利用竹、木等植物纤维、原生态树脂、重钙粉为原料,采用共挤复合一次成型工艺实现产品其表层（植物纤维同质透心柔性卷材）与芯层（植物纤维微发泡材料）一次复合成型。同时,结合开炼、捏合和无胶黏剂复合等多项成型工艺新技术。产品生产和使用过程绿色环保,具有广阎的发展前景。     

热压温度对热压过程中板坯芯层温度变化影响的研究

纤维板热压过程中板坯芯层温度是否能迅速达到胶的固化温度是影响产品质量和生产率的重要因素之一。板坯热压过程中的传热速率受很多因素影响,如热压温度、板坯含水率、密度和厚度等,其中热压温度是生产中较易控制的工艺参数之一。通过探讨热压过程中板坯芯层温度变化规律与热压温度的关系,研究不同热压温度对板坯芯层温度变化的影响,为优化热压工艺条件提供理论依据。     

制造工艺对稻壳-木质剩余物复合板2h吸水厚度膨胀率的影响

采用均匀设计方法,以稻壳和木质剩余物为主要原料制备复合板,并进行2h吸水厚度膨胀率的测试。对测试结果进行逐步回归分析,讨论密度、芯层比例、表层施胶量、芯层施胶量、固化剂用量、热压温度、热压压力和热压时间对复合板2 h吸水厚度膨胀率的影响。在实验研究范围内,除热压时间外,其他因素对复合板2h吸水厚度膨胀率都有不同程度的影响。通过择优选择制备工艺,可在低成本的条件下,降低复合板的2h吸水厚度膨胀率。     

热压工艺对翅荚木芯细木工板性能的影响

为探讨速生翅荚木人工林木材作为芯板制作细木工板的可行性及其适宜的热压工艺参数，以10年生翅荚木人工林木材为研究对象，对翅荚木芯细木工板制备的工艺技术进行了优化，分析了热压工艺因素对翅荚木芯细木工板性能的影响。结果表明：热压工艺因素对翅荚木芯细木工板含水率的影响程度从高到低依次为温度>时间>压力；对翅荚木芯细木工板密度、横向静曲强度、浸渍剥离长度的影响程度从高到低依次为温度>压力>时间。翅荚木芯细木工板适宜的热压工艺参数为：热压温度135℃，热压压力1.2 MPa，热压时间3 min。以翅荚木作芯层研制的细木工板均达到GB/T5849—2016《细木工板》要求，说明翅荚木适合作为细木工板的原料。     

环境温度对刨花板生产质量的影响及改进方法

本项研究对气温(尤其在冬季)是如何影响刨花板生产进行了分析。通过对不同季节时的两种极端情况——较高的板坯芯层温度和较低的板坯芯层温度在热压过程中板坯芯层渴度的变化,进一步说明了芯层温度对热压时间以及刨花板质量的影响,并就如何解决这一问题提出了建议。     

刨花板喷蒸热压

刨花板喷蒸热压王洁瑛，刘正添（北京林业大学北京１０００８３）热压是刨花板生产的关键工序。热压的间取决于板坯芯层的升温速度及胶粘剂的固化速度。传统的热压方法依靠热压板（或垫板）向板坯的接触传热，芯层升温慢，尤其是在生产厚板的情况下，单纯依靠提高热压温度...     

重载纤维模塑材料热压成型的传热规律研究

以重载纤维模塑材料为研究对象,采用多通道温度传感器和称重法测定材料不同位置的温度与含水率变化,研究了重载纤维模塑材料热压成型传热过程的影响因素,揭示了材料内部温度随含水率变化的规律。研究结果表明:热压过程中,重载纤维模塑材料芯层温度变化包含快速升温、过渡、温度维持和后升温4个阶段;浆种木素含量越低,升温段的升温速率越快;提高热压温度和热压压力均会导致芯层汽化温度升高,降低热压温度、热压压力或定量均能缩小表层与芯层温度差;热压过程中,重载纤维模塑板坯由表层至里层,温度逐渐降低,含水率逐渐升高;芯层温度与热压温度和热压压力均具有显著线性正相关性,模型拟合优度均较高(R2≥0.918),可以用热压温度和热压压力预测芯层温度,其变化范围在103.6~126.4℃之间。芯层温度与芯层含水率具有较好的线性正相关关系,可以通过芯层温度预测出重载纤维模塑材料的芯层含水率。     

竹重组材料复合工艺与性能试验初探

对竹重组材料复合工艺进行了研究,分析了热压过程中压力、温度、时间等不同工艺因素对板材的静曲强度、弹性模量、吸水厚度膨胀率等质量指标的影响,探讨复合工艺的最佳工艺参数。对18 mm和28 mm厚度的板材进行板坯芯层温度变化测试,探讨板坯厚度对热压时间的影响。结果表明:当热压压力4.5 MPa、热压时间1.5 min·mm-1、热压温度155℃、表层含水率18%时热压效果最好。板坯厚度影响传热效果,厚度增大,升温时间也越长。     

微米木纤维模压制品质量控制工艺方法研究

微米木纤维模压制品质量控制工艺方法应考虑模具系统刚度的控制及表面质量的控制、密度与握钉力的控制、成型回弹率的控制及材料流动性的控制等因素.本研究提供了关键工艺参数争模具系统刚度的设计条件,建立了密度与握钉力的关系方程,分析了成型回弹率和纤维变形能的计算方法.     

Economics of smallholder rubber expansion in Northern Laos

In Northern Laos, as elsewhere in the Southeast Asian uplands, there is an agricultural transition underway from subsistence production based on shifting cultivation to commercial production based on tree crops. In response to demand from China, rubber smallholdings are being established by shifting cultivators in Northern Laos, encouraged by government land-use policy. We examine the bio-economics of smallholder rubber production in an established rubber-growing village and model the likely expansion of smallholder rubber in Northern Laos. Data were obtained from key informants, group interviews, direct observation, and a farm-household survey. Latex yields were estimated using the Bioeconomic Rubber Agroforestry Support System (BRASS). A financial model was developed to estimate the net present value for a representative rubber smallholding. This model was then combined with spatial data in a Geographical Information System (GIS) to predict the likely expansion of rubber based on resource quality and accessibility. Implications are drawn for upland development in the region.     

Powdery mildew disease of rubber tree

Powdery mildew disease of rubber trees affects young rubber leaves, buds, inflorescences and other immature tissues reducing rubber latex yields by up to 45%. The disease is present in all rubber‐growing regions, with a high incidence rate in subtropical environments. The causal agent of powdery mildew disease of rubber trees was first described as Oidium heveae, but later research on the morphological characteristics suggests that O. heveae was in the past confused with Erysiphe quercicola. However, the most appropriate classification is still under debate between the genera Golovinomyces or Podosphaera. Molecular and phylogenetic analyses have established some relationships between rubber powdery mildew fungus and other powdery mildew species, but the generic sexual state of rubber powdery mildew fungus has not yet been established. Rubber powdery mildew conidia are wind‐spread spores that are produced in great numbers when growth conditions of the disease are favourable. The optimum conditions for conidial germination are 97–100% relative humidity and temperatures between 25 and 28°C. While some newly bred rubber clones have shown resistance to the disease, it can also be controlled with a number of fungicides and biological control agents. It is clear from recent knowledge about climate–fungus relationships that changes in weather strongly influence disease incidence and severity. The aim of this review is to highlight the classification conflicts, main causes and influencing factors behind the disease spreading, as well as draw attention to the impact of weather changes on the outbreaks of the disease. The information in this review will be helpful to adopt better control measures of the powdery mildew disease of rubber, especially in higher humidity areas, thereby minimizing the loss of rubber yields due to this disease.     

Integration of animals in rubber plantations

This paper describes a rather unique agroforestry approach of integrating animals (sheep, poultry and bees) in smallholder rubber plantations. The approach is based on the existence of surplus family labour, utilization of interspaces between the rows of rubber, availability of cheap and nutritious animal feed and presence of favourable microclimate for animal growth under rubber. Results of trials carried out by the Rubber Research Institute of Malaysia since the 1970's are presented.Rotational system of broiler production under rubber was found to be technically, socially and economically feasible, providing a net return on family labour of M$370–M$825 per consignment of rearing 500 birds. Sheep rearing under rubber also appeared to be very attractive and practical; apart from producing meat for sale it also served as a biological weed control measure. Cost of controlling the weeds commonly found under rubber plantations could be reduced by about 21% over the usual method by using sheep grazing for weed control. The Internal Rate of Return (IRR) from sheep rearing can be as high as 44%. Details of operation and management aspects of sheep integration under rubber are given.Bees kept under rubber feed on nectar produced by inflorescence and tips of young rubber shoots and also on flowers of intercrops and weeds. TheApis cerana species was found to be suitable producing about 3 kg of honey per colony per harvest.     

Plant and bird diversity in rubber agroforests in the lowlands of Sumatra,Indonesia

Plant and bird diversity in the Indonesian jungle rubber agroforestry system was compared to that in primary forest and rubber plantations by integrating new and existing data from a lowland rain forest area in Sumatra. Jungle rubber gardens are low-input rubber (Hevea brasiliensis) agroforests that structurally resemble secondary forest and in which wild species are tolerated by the farmer. As primary forests have almost completely disappeared from the lowlands of the Sumatra peneplain, our aim was to assess the contribution of jungle rubber as a land use type to the conservation of plant and bird species, especially those that are associated with the forest interior of primary and old secondary forest. Species-accumulation curves were compiled for terrestrial and epiphytic pteridophytes, trees and birds, and for subsets of ‘forest species’ of terrestrial pteridophytes and birds. Comparing jungle rubber and primary forest, groups differed in relative species richness patterns. Species richness in jungle rubber was slightly higher (terrestrial pteridophytes), similar (birds) or lower (epiphytic pteridophytes, trees, vascular plants as a whole) than in primary forest. For subsets of ‘forest species’ of terrestrial pteridophytes and birds, species richness in jungle rubber was lower than in primary forest. For all groups, species richness in jungle rubber was generally higher than in rubber plantations. Although species conservation in jungle rubber is limited by management practices and by a slash-and-burn cycle for replanting of about 40 years, this forest-like land use does support species diversity in an impoverished landscape increasingly dominated by monoculture plantations.     

浅谈板式橡胶支座的安装

本文从板式橡胶支座安装步骤及注意事项二方面,详细阐述了正确安装支座对支座使用效果 和寿命有重要意义。     

Trade-offs between rubber production and maintenance of diversity: the structure of rubber gardens in West Kalimantan, Indonesia

The goal of this study was to assess the potential of small-holder rubber cultivation in agroforestry gardens to fulfill simultaneously the goals of conservation and sustainable rural development. I examined the structure and species composition of trees in 11 rubber gardens in West Kalimantan, Indonesia, using a single 0.10 ha plot per garden. Although 41 distinct morphotypes were encountered, rubber (Hevea brasiliensis) dominated the sample of 370 trees. Richness within plots varied (3–15 morphotypes), as did the predominance of rubber (24–97% of all basal area, 24–91% of all individuals). The importance of rubber within a garden was significantly negatively correlated with the number of morphotypes present. This result suggests that tree diversity may limit potential productivity of rubber gardens. Thus, small-holders may not be willing to maintain diversity at the scale of a single garden. Although species-accumulation curves indicate that substantial tree diversity may exist across all rubber holdings, diversity is likely to be lost from the system if individual owners reduce species richness in their gardens. Rubber agroforestry as currently practiced in West Kalimantan is not an ideal model for matching rural development needs with the achievement of conservation goals. Other models, such as tengkawang- and durian-based fruit gardens, do exist in Kalimantan and elsewhere, and should be evaluated for incorporation into policy and development strategies.     

Does ‘jungle rubber’ deserve its name? An analysis of rubber agroforestry systems in southeast Sumatra

Jungle rubber is a blanced, diversified system derived from swidden cultivation, in which man-made forests with a high concentration of rubber trees replace fallows. Most of the income comes from rubber, complemented with temporary food and cash crops during the early years. Perennial species that grow spontaneously with rubber provide fruits, fuelwood and timber, mostly for household consumption. Jungle rubber enables lower incomes per land unit or man-day than weed-free plantations using selected rubber clones. Yet it requires much less input and labour since wild woody species protect rubber from grass weeds and mammalian predators. With a structure and biodiversity similar to that of secondary forest in its mature phase, jungle rubber belongs to complex agroforestry systems. It has accommodated increasing population densities, while preserving a forest-like environment.Yet farmers' income from jungle rubber is declining due to the exhaustion of forest reserves and reduced land availability. New research and extension options could help in improving the productivity of jungle rubber. Better transportation and marketing are needed for increasing the income from non-rubber output. Short-term, small-scale credit schemes could help farmers adopt high-yielding rubber varieties. Research should participate in creating new management methods for selected rubber based on agroforestry to reduce maintenance costs, enabling smallholders to plant high-yielding rubber at lower cost, and without losing too much of the present biodiversity and economic diversity.

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Résumé Dérivées de l'essartage, les forêts à hévéa forment un système de culture équilibré et diversifié, où le recrû forestier est remplacé par une forêt anthropique à forte concentration d'hévéas. L'essentiel du revenu provient des hévéas, complétés par des cultures vivrières et commerciales pendant les premières années. Les espèces prérennes qui se développent spontanément avec les hévéas fournissent des fruits et du bois, principalement pour l'autoconsommation. Le revenu tiré de ce système est inférieur à celui de plantations d'hévéa clonal entretenues. Il nécessite cependant moins d'investissements en intrants et en travail grâce au rôle protecteur de courvert forestier vis-à-vis des adventices herbacées et des mannifères prédateurs. Avec une structure et une diversité d'espèces comparable à celles d'une forêt secondaire, ce système fait partie des agroforêts complexes. Il a fourni depuis 1910 l'essentiel du revenu d'une population en croissance rapide tout en préservant un environnement forestier.Le revenu que tirent les paysans des forêts à hévéa est en déclin en raison de l'augmentation de la population. De nouvelles orientations de la recherche et du développement pourraient permettre d'améliorer la productivité de ce système. Le revenu tiré de la composante nonhévéa pourrait être augmenté grâce à une amélioration des transports et de la commercialisation. Le crédit à court terme et à petite échelle permettrait aux paysans d'adopter des variétés d'hévéa sélectionné et d'augmenter ainsi leurs revenus. La recherche devrait aider à mettre au point de nouvelles méthodes de gestion des hévéas sélectionnés, de type agroforestier, afin de réduire les coûts d'entretien. Les paysans purraient ainsi planter des hévéas hauts producteurs à moindres frais, et conserver partiellement la diversité économique et écologique du système actuel.

     

板式橡胶支座的发展历程与现状

本介绍了板式橡胶支座的起源、发展应用，并对其工作原理及计算方法进行了阐述。总结了板式橡胶支座的优点，指出板式橡胶支座将被更广泛地应用于桥梁结构中。     

High accuracy rapid prediction and feasibility of on-site nondestructive estimation of Para rubber quality by spectroscopic methods

The aim of this study was to investigate convenient spectroscopic evaluation method of Para rubber quality. Ultra violet–near infrared (UV–NIR 370–1085 nm) spectra of latex were measured in transmittance mode. Calibrations for total solid content (TSC) and dry rubber content (DRC) were developed using spectral data set with aid of partial least square regression analysis using 57 samples. UV–NIR spectra of latex provided good regression models between measured and predicted values of TSC and DRC with determination coefficient for cross-validation of 0.96 and 0.97, respectively. The ranks were 2 and 1, respectively. This study suggests high accuracy in-line quality control of latex using UV–NIR spectroscopy. The long wavelength NIR spectra of bark were scanned to check the feasibility of on-site evaluation of latex quality by measuring the NIR spectra of standing tree. From the observation of near infrared spectra, it was shown that there was more latex signal in outer part of wood bark than in inner part of wood bark. This result suggests that the focal point should be on the outer part of bark to get the signal of latex when we measure the spectra of standing tree.     

The household economics of rubber intercropping during the immature period in Northeast Thailand

In order to alleviate poverty in Northeast Thailand, the Thai government has promoted rubber farming, which has expanded at the expense of annual crops. Because of a long immature period, planting rubber represents a loss of income for poor farmers in the very first years. This paper analyzed how rubber intercropping during the immature period helps farmers to compensate for this loss of income. Economic performances of the most widespread rubber farming systems were analyzed using information collected from a questionnaire addressed to 35 farmers in Buriram province. A sub-sample of 22 farmers was further interviewed to estimate the contribution of rubber intercropping in the formation of the total annual income during the immature period. The results showed that interest in rubber intercropping has grown, with cassava and rice as the main associated crops. With additional costs of about 14,169 ?/ha/year over monospecific rubber plantations, rubber-cassava intercropping systems generated a gross margin estimated at 11,340 ?/ha/year for a 3-year period. Compared to a monospecific rubber plantation, rubber-cassava intercropping systems reduced management costs by 59% over the 6-year period of rubber immaturity. The cash-income drawn from intercropping ranged from 0 to 26.8% of the household’s total annual income, which can be of considerable importance for low-income farmers.