聚酰胺及其改性材料自然老化行为研究及预测

在自然环境(武汉)下进行了两年半的老化曝晒实验,随着老化时间的增长,聚酰胺材料的吸水率逐渐增加,力学性能下降,表面出现了不同程度的裂纹.通过吸水率测试和力学性能的比较,发现环境湿度影响聚酰胺老化过程中力学性能变化,湿度越大,材料力学性能下降越快;改性后,即添加了玻璃纤维后的聚酰胺,能够在一定程度下减缓材料老化行为.对材...     

聚碳酸酯在干热环境老化后表观性能与形态研究

开展聚碳酸酯(PC)材料在我国吐鲁番和若羌典型干热自然环境暴晒试验,对试验前后PC材料的色差、黄色指数、光泽度、雾度、透光率等光学性能和表面形貌进行测试与表征,研究PC材料在吐鲁番和若羌两个试验站的老化行为差异。结果表明,PC材料在干热环境暴晒出现了明显的老化失效现象,而且试样在吐鲁番的老化程度大于若羌,说明在辐照、温度和湿度三个主要环境因素中,当温度与辐照量同时处于较高水平时能加剧PC材料的老化。     

文摘

文摘《塑料暴露于玻璃下的日光式自然气候或人工光后颜色和性能变化的测定研究》──《老化与应用》１９９４（１）２２～３０（中）：报道以多种塑料试样在不同的暴露试验过程中，颜色和性能变化的测试研究结果。试验研究以ＩＳＯ４５８２为主要参考依据，验证其所推荐的...     

流沙河流域不同生态恢复程度下植物群落特征研究

根据野外调查的数据分析,对流沙河流域干旱河谷不同生态恢复程度下的群落特征进行了研究。调查样方中分布的植物共33科61属66种。在林地中,共有植物24科41属45种。但是不同恢复程度中的物种组成有显著差异：Ⅰ级恢复程度中有11科17属17种,Ⅱ级恢复程度中有13科21属21种,Ⅲ级恢复程度中有18科27属31种;主要物种为松科、蔷薇科、马桑科、禾本科、菊科植物;物种丰富度依次为Ⅲ级〉Ⅱ级〉Ⅰ级;生物量的变化特点为对照（0．31t／hm^2）〈Ⅰ级（5．66t／hm^2）〈Ⅱ级（200．29t／hm^2）〈Ⅲ组（307．06t／hm^2）。在园地中,共有植物19科37属37种;物种丰富度变化不明显,梨树始终在样方中占主导;生物量的变化：Ⅲ级（217．67t／hm^2）〉Ⅱ级（72．60t／hm^2）〉Ⅰ级（39．71t／hm^2）〉对照（0．21t／hm^2）;果树产量变化Ⅰ组（31t／hm^2）〈Ⅱ组（54t／hm^2）〈Ⅲ级（195t／hm^2）。     

高分子材料服役寿命预测方法最新进展

高分子材料在使用过程中,由于受各种环境因素作用,会逐步出现性能下降,甚至丧失使用价值的老化现象,不仅造成资源浪费,更形成安全隐患。为应对老化问题,研究者以各种宏观性能或微观结构、组份的变化来表征老化过程,针对高分子材料的环境适应性开展了大量研究工作,并在此基础上提出了不同的老化机理和服役寿命预测方法。从高分子材料老化过程表征的视角,综述了近年来高分子材料服役寿命预测方法的最新进展。     

三种涂层在模拟热带海洋大气环境中的性能退化研究

为了考核评价舰船、舰载机等装备用三种涂层在热带海洋大气环境中的性能退化情况，设计了涂层在实验室模拟热带海洋大气环境中太阳辐射试验、湿热试验和盐雾试验的组合循环试验方法。通过实验室组合循环试验，分别检测了试验前后涂层的形貌、失光率、色差、附着力和电化学阻抗等数据。试验结果表明，随着试验时间的延长，三种涂层均出现不同程度的老化，失光率和色差呈增大趋势，附着力降低；但试验前后其老化机理未发生明显变化，电化学交流阻抗值基本保持在109Ω以上，涂层的厚度基本保持不变。综合三种涂层的性能退化对比，在工程实际应用中推荐优先选用4号或10号涂层。     

文摘

实际上所有聚合材料的性能都随时间变化。研制在老化过程中具有高稳定性的聚合材料是有现实意义的。这些材料必须具备耐抗实际使用条件的环境因素综合作用的性能以及长期贮存稳定性。研究了聚酰胺、聚丙烯、聚对苯二甲酸丁二醇酯和甲醛一二氧戊环共聚物为基的复合材料的介电性能及它们在高温和潮湿条件下老化前后的性能变化情况。所得结果可以预测由这些材料制作的零部件在实际运行条件下的使用可能性。     

文摘

文摘▲《用温度－时间模拟原理预测聚合物的热老化》──１９９１（６）２３～２６（俄）：制订一种在较短时间内取得的实验室试验结果预测聚合物在天然条件下长期热老化时的性能变化的方法，颇有意义。作者用温度一时间模拟原理对４批聚酰亚胺薄膜进行了试验研究。结果表...     

基于高分子参考材料透光率变化的环境应力测试装置及方法研究

不同地区的太阳辐照、气温和湿度等环境因素对产品的综合作用影响,即为综合环境应力。对于材料老化领域,综合环境应力的精准量化测量,是开展环境试验以及进行材料及产品性能设计的前提和基础。本文通过设计一种基于高分子参考材料透光率变化的环境应力测试装置,可以连续测量高分子材料透光率变化,以此量化评定环境应力。     

中药川附子中25种化学元素的分析研究

本文较全面系统地研究了川附子的化学组成。样品用硝酸-高氯酸消解后，借联用技术(ICP—AES与极谱法或HG—AFS等)测定21种化学元素，用GF—AAS法测定痕量钼并参照GB测定卤素(氟、氯和碘)。应用上述方法弄清了川附子用传统工艺炮制前后、各种元素的含量及其浓度变化，从而为川附子的开发、出口提供科学依据和测试手段。     

Adsorption of trace metals on glass fiber filters

Filters, containing glass-fiber (GF) filter material, are commonly used as the primary filter or as the prefilter in sampling natural waters and laboratory experiments with high concentrations of suspended solids. We observed that GF filter material removed substantial quantities of trace metals from solutions of low ionic strength at near neutral and slightly acidic pH. The GF material sorbed essentially all Pb and Ag from 5-mL aliquots of solutions containing 0.054 and 0.093 mM, respectively. Somewhat less Ni was sorbed from a 0.099 mM solution. This material retained about 43 micromol of Ag per gram of GF material (4600 microg/g). The Ag and Ni sorption was highest at low KNO(3) concentrations (as background electrolyte) and decreased to a constant concentration of sorbed metal at approximately 10 mM KNO(3). Glass-fiber filter material should only be used with careful testing for the elements of concern under conditions that closely match expected environmental or experimental conditions.     

Lability of drinking water treatment residuals (WTR) immobilized phosphorus: aging and pH effects

Time constraints associated with conducting long-term (>20 yr) field experiments to test the stability of drinking water treatment residuals (WTR) sorbed phosphorus (P) inhibit improved understanding of the fate of sorbed P in soils when important soil properties (e.g., pH) change. We used artificially aged samples to evaluate aging and pH effects on lability of WTR-immobilized P. Artificial aging was achieved through incubation at elevated temperatures (46 or 70 degrees C) for 4.5 yr, and through repeated wetting and drying for 2 yr. Using a modified isotopic ((32)P) dilution technique, coupled with a stepwise acidification procedure, we monitored changes in labile P concentrations over time. This technique enabled evaluation of the effect of pH on the lability of WTR-immobilized P. Within the pH range of 4 to 7, WTR amendment, coupled with artificial aging, ultimately reduced labile P concentrations by > or = 75% relative to the control (no-WTR) samples. Soil samples with different physicochemical properties from two 7.5-yr-old, one-time WTR-amended field sites were utilized to validate the trends observed with the artificially aged samples. Despite the differences in physicochemical properties among the three (two field-aged and one artificially aged) soil samples, similar trends of aging and pH effects on lability of WTR-immobilized P were observed. Labile P concentrations of the WTR-amended field-aged samples of the two sites decreased 6 mo after WTR amendment and the reduction persisted for 7.5 yr, ultimately resulting in > or = 70% reduction, compared to the control plots. We conclude that WTR application is capable of reducing labile P concentration in P-impacted soils, doing so for a long time, and that within the commonly encountered range of pH values for agricultural soils WTR-immobilized P should be stable.     

外绝缘用液体硅橡胶的自然老化因素研究

近年来,液体硅橡胶(Liquid Silicone Rubber,LSR)已经在外绝缘领域得到了较为广泛的应用,但是目前对其耐老化性能的研究还不够深入。尤其是在中国南方地区使用时,高温、高湿环境更容易导致液体硅橡胶的老化。在许多地区都观察到了电流、电压互感器的液体硅橡胶绝缘外套的龟裂、老化现象,对设备的安全运行产生了影响。本文设计并实施了在光照、高温、高湿、电晕等老化因素作用下的液体硅橡胶人工老化试验,并对老化试验后的样品进行了硬度、力学性能、憎水性、光泽度以及SEM、FTIR等微观性能试验和分析。认为在光照作用下,高温、高湿环境对液体硅橡胶具有加速老化作用,表现为硬度上升、憎水性下降、光泽度下降,并且在表面出现细微裂纹。     

汽车内饰材料老化试验研究

本文介绍了汽车内饰材料常见的老化试验方法:人工加速老化试验、IP/DP箱暴晒和整车暴晒,分别讨论三种试验方法涉及的规范以及操作性.人工加速老化试验能快速掌握汽车内饰材料老化性能,缩短材料研发周期;IP/DP箱和整车对内饰件或其装配件进行的老化试验降低内饰材料加工工艺存在的风险,确保了内饰材料质量.整车暴晒收集的数据为人...     

东湖磷酸酶活力及其生态学意义研究

本文对东湖磷酸酶活力(PA)的来源,不同湖区活力水平的比较,及其与主要环境因子的关系作了初步研究。结果表明,东湖水柱中磷酸酶活力主要来自藻类,底泥中则主要来自细菌;在东湖磷浓度波动范围内,磷对碱性磷酸酶活力(ALPA)无明显抑制,实验室条件下相当于环境水平的磷浓度不能抑制PA;光照促进藻类PA的增加;溶解氧有利于藻类PA提高,对细菌PA则相反。     

EFFICACY AND COST OF AQUATIC WEED CONTROL IN SMALL PONDS'

ABSTRACT: Twenty, 0.2 hectare ponds were utilized for a four-year evaluation of three aquatic vegetation control techniques: a combination of inorganic fertilization and mechanical harvesting, aquatic herbicides, and grass carp (Ctenopharyngodon idella). Ponds used for herbicide and grass carp treatments were managed at three levels of aquatic vegetation (none, 40 and 70 percent plant occupation). Submersed vegetation was not controlled with inorganic fertilization. Vegetation levels were maintained for less than 30 days after mechanicai harvesting. Submersed macrophytes were not completely eliminated with herbicides, but the herbicide treatments utilized were effective at maintaining aquatic vegetation above 30 percent pond volume occupation. Grass carp consumed all species of submersed vegetation at the stocking densities used in this study; therefore, planned levels of submersed macrophytes were not maintained. Grass carp did not consume all floating leaf vegetation, but after four years some grass carp ponds did have lower densities of floating leaf plants. Fertilization costs were $608/hectare/year, and mechanical harvesting costs were $1979/hectare/year, resulting in a total aquatic vegetation treatment cost of $2587/hectare/ year. Herbicide costs for the different treatment levels ranged from $417/hectare/year to $1339/hectare/year over the four-year period. Grass carp were the most economical vegetation control measure tested, with costs ranging from $159/hectare/year to $248/hectare/year for the four-year study.     

Assessment of <Emphasis Type="Italic">Gmelina arborea</Emphasis> sawdust–cement-bonded rainwater storage tank

The performance of a mixture of a forest bye product and cement for the production of storage structure for harvested rainwater was assessed. Three mix ratios of Cement: Gmelina arborea sawdust 3.0:1.0 (specimen A), 2.5:1.0 (specimen B) and 2.0:1.0 (specimen C) were considered. Engineering properties and dimensional stability of the different mix-ratios were monitored from prototypes cylindrical pots and test billet specimens. Possible change in quality of stored rainwater, with time was monitored in all the three cases. Water quality parameters monitored include pH, hardness, total suspended solids, alkalinity, acidity and total dissolved CO₂. The tensile stress obtained were 110, 104, and 95 N/mm², while the compressive strength were 5,000, 3,000, and 2,000 kN for specimens A, B and C respectively. Accelerated aging test showed that sample A were more resistant to deformation, while specimen C were more susceptible to change in structure over time. Similarly, the values of tensile and compressive strength after accelerated aging test increased in the order of specimen A > B > C. Except in specimen C where significant differences in alkalinity and acidity were observed, there were no significant differences in quality of the water stored in the pots after 2 months of storage. The results indicate the suitability of the Gmelina arborea waste as an alternative in constructing water storage structures in rural communities.     

Effects of impurities on the removal of heavy metals by natural limestones in aqueous systems

Effects of impurities on the removal of heavy metals by natural limestones in aqueous solutions were studied by evaluating various factors including limestone concentration, pH, contact time and temperature. Solutions of Pb(II), Cd(II), Cu(II) and Zn(II), prepared from chloride reagents at a concentration of 10 mg/L, were studied in a batch method. Four natural limestone samples, collected from the Campanian-Maastrichtian limestone beds in Tunisia, were used as adsorbents. Sorption experiments indicated that high removal efficiencies could be achieved. Limestone samples containing impurities, such as silica, iron/aluminum oxides and different kinds of clay minerals, demonstrated enhanced sorption capacity, nearing 100% removal in some cases. Kinetic experiments showed that the sorption of metal ions occurred rapidly at a low coverage stage, and that solutions were nearly at equilibrium after 60 min. Data trends generally fit pseudo-second order kinetic, and intra-particle diffusion, models. The following conditions were found to promote optimum, or near-optimum, sorption of heavy metals: 1) contact time of more than 60 min, 2) pH = 5, 3) >3 g/L limestone concentration and 4) T = 35 °C. The results of this study suggest that the limestones from northern Tunisia, that contain higher amounts of silica and iron/aluminum oxides, are promising adsorbents for the effective removal of toxic heavy metals from wastewaters.     

利用高效复合菌净化城市微污染水的静态试验研究

EM经三种培养基富集培养后，用其培养液对微污染水进行净化处理。结果表明：三种培养液在曝气或静置的运行条件下，对微污染水中的COD和氨氮有稳定良好的去除效果，其去除率分别为50％和85％；对磷酸盐的去除随运行条件的不同而不同，曝气条件下比静置条件要好，其去除率也都在60％以上。试验证明：EM培养液对微污染水有良好的净化能力。