药用干燥剂(SiO2)吸湿特性及动力学研究

采用吸附的方法研究药用干燥剂(SiO2)在不同温度(25,40,60℃)和相对湿度(35％,45％,60％,75％,90％)下放置48 h时的吸湿特性.结果表明,温度一定时,吸湿量随相对湿度的增加而增加.相对湿度一定时,随着温度升高,吸湿量有一定变化.从动力学角度分析药用干燥剂的吸湿特性,采用一阶模型和Peleg模型进...     

温控纱线与吸湿排汗纱线及其织物的吸湿能力

介绍了温度调节纱线与吸湿排汗纱线的性能特点和吸湿原理,对其进行了毛细管效应的测试,分析了其吸湿排汗能力的大小,并指出拥有这两种类型纱线的织物能很好地满足人们对温度、吸湿排汗舒适性能的要求。     

Analysis of Drying Kinetics and Moisture Distribution in Convective Textile Fabric Drying

The drying process of crude cotton fabric is analyzed under two main aspects: analysis of moisture distribution inside the textile sheet, and analysis of certain operational convective drying process variables. Experimental apparatus consisted of a drying chamber in which samples of pure cotton textile were suspended inside the drying chamber and exposed to a convective hot air flow. The influence of the operational variables on the drying process behavior was studied by two different ways with generalized drying curves. The behavior of moisture distribution profiles was compared to average moisture content of the textile fabric verifying whether average values were able to represent the textile moisture content during the drying process.     

几种天然多糖的吸湿和保湿性能的初步研究

通过干燥器控制湿度的方法对魔芋葡甘聚糖、羧甲基纤维素钠、壳聚糖、海藻酸钠等多糖与常用保湿剂甘油进行了吸湿和保湿性能测试.结果表明,在高相对湿度条件下,各试样的吸湿能力依次为:羧甲基纤维素钠＞甘油＞海藻酸钠＞魔芋萄甘聚糖＞壳聚糖;在低相对湿度条件下,各试样的吸湿能力依次为:甘油＞羧甲基纤维素钠＞海藻酸钠＞魔芋葡甘聚糖＞壳聚糖.各试样的保湿能力依次为:壳聚糖＞魔芋葡甘聚糖＞海藻酸钠＞甘油＞羧甲基纤维素钠.此外,采用热重分析法(TGA)对各试样的失重率进行了测试,其失重曲线与保湿曲线趋势一致.     

镁水泥材料的吸潮返卤性能研究

本文通过定量测定镁水泥板材中总氯离子、自由氯离子、游离氯化镁、钾钠等离子的含量及其与吸潮返卤的关系,并结合物相组成分析,研究探讨了镁水泥材料的吸潮返卤机理.结果表明,自由氯离子是引起镁水泥材料吸潮返卤的主要原凶,其中,由游离氯化镁中的自由氯足引起吸潮返卤的第一原因.镁水泥材料的抗水性对吸潮返卤也有一定的影响.因此,选择合理的MgO/Mgcl<,2>物质的量比、控制原料氯化镁中钠钾等杂质的含量和提高抗水性,是解决镁水泥材料吸潮返卤的重要技术措施.     

硼酰化钴的吸湿性及其对胶料粘合性能的影响

介绍硼酰化钴的特殊分子结构及其吸湿性原理,分析环境温度、相对湿度和吸湿时间对硼酰化钴吸湿性能的影响。结果表明,相同条件下,环境温度越高、相对湿度越大、吸湿时间越长,硼酰化钴的吸湿程度越大,胶料的粘合性能下降越明显。     

Fractal Nature of Fluorescence Quenching and its Relation to Percolative Conduction in Water-in-Oil Microemulsions

Results of fluorescence quenching and electrical conductivity measurements in water-in-oil microemulsions were analyzed in terms of fractal models. It was found that for SDS/water/pentanol/alkane microemulsions there exists a connection between the fractal nature of the reaction domain and the magnitude of electrical conductivity. Conductivity values increase as the domain becomes less fractal.     

Dependence of Dielectric Properties and Percolative Behavior on Phase Separation Structure Induced by Heterogeneous Carbon Nanofiber Distribution in Polymer Blend Nanocomposites

Many thermoplastics currently used in industry are in fact polymer blends and there is a pressing need to understand the dependence of the dielectric properties and percolative behaviors of the multi‐phase polymers with heterogeneous nanofiller distributions. When nanofillers distribution occurs in a polymer blend with phase separation, the dielectric properties and percolative behaviors have been shown to be more complex, and very sensitive to the distribution of the nanofillers. As a basis, the dielectric properties and alternating current (AC) conductivities of the binary carbon nanofiber (CNF)/high density polyethylene (HDPE) composite system were first characterized. Subsequently the properties of the ternary CNF/ultra‐high molecular weight polyethylene (UHMWPE)/HDPE composites were compared and analyzed. Combined with the evidence showing the phase separation of UHMWPE and HDPE and the CNFs exclusively dispersed in HDPE phase, it was inferred that UHMWPE acting as a non‐conductive additive, dramatically changed the uniform CNF presence in the matrix into a heterogeneous distribution. As a result, the dependencies of dielectric properties and conductivities on frequency were strongly affected, and in particular the percolative characteristics showed significantly increased dependencies.

     

水化硅酸钙的晶型调控及其对吸/放湿性能的影响

为改善水化硅酸钙的孔隙结构、改善其湿度调节性能,以硅灰、氢氧化钙和水为原料,采用水热反应方法合成出预期类型的水化硅酸钙晶体,并对反应产物的微观结构和吸/放湿性能进行细致表征.研究结果表明,200℃合成样品的吸/放湿率随反应时间的延长呈现先升后降的趋势,在4 h时达到最大值,原因在于CSH(B)型水化硅酸钙的形成及其向托贝莫来石的晶型转化;90℃下CSH(B)晶型在较长时间内保持稳定,样品吸/放湿率受水热时间的影响不明显.微观结构对比分析认为,CSH(B)与托贝莫来石均以片状晶体形式存在,而托贝莫来石晶体更为完整、粗大;细小晶体所构成的堆聚结构中存在较大量的介孔,最可几孔径峰位于16 nm附近,但其含量随CSH(B)向托贝莫来石的晶型转变过程而明显减小,表现为CSH(B)型水化硅酸钙的吸/放湿能力明显高于托贝莫来石.研究成果对于水化硅酸钙基建筑功能材料的研发具有一定理论指导意义和工艺价值.     

Kinetics of Moisture and Heat Transfer between a Capillary Porous Body and an Aerosol

The kinetics of moisture and heat transfer between a capillary porous body and a gas–vapor–liquid medium with a dispersed liquid phase (aerosol) is described theoretically.     

Moisture Diffusivity in Rice Components During Absorption and Desorption

Moisture diffusivity values of different rice kernel components, namely endosperm, bran and husk, are required to solve mathematical models describing absorption and desorption processes. In addition to the rice variety and temperature, the moisture diffusivity also depends on its instantaneous moisture content or water activity (a_w) and whether rice is absorbing or desorbing moisture. This research was undertaken to determine moisture diffusivity values of rough rice components in different a_w ranges during absorption and desorption. Experiments were performed to measure sorption rates of different rice forms, including white rice, brown rice, and rough rice kernels. Mathematical models were developed to predict their moisture distribution during moisture sorption processes. These models were solved by finite element method using Comsol Multiphysics® simulation program. Moisture diffusivity values of different rice components were calculated and found to be different during absorption and desorption. Diffusivity of rice endosperm was higher during desorption than absorption at a_w higher than 0.20 and increased with an increase in a_w in 0.20–0.80 a_w range. Diffusivity of bran remained almost the same with a_w while diffusivity of husk decreased with an increase in a_w. Results obtained in this research demonstrated that the moisture diffusivity of different rice components varies significantly with the change in water activity or moisture and should be accounted in the mathematical models.     

组织结构对三维机织物的吸水导湿性能影响

以差动毛细效应为基础,细旦丙纶和黏胶长丝为原料,设计织造了正交结构、角联锁结构和多层接结结构的三维机织物,并对各织物的吸水导湿性能进行测试分析。结果表明:正交结构三维机织物的吸水导湿性能最优。     

Moisture Nonuniformity in Drying Paper: Measurement and Relation to Process Parameters

Local nonuniformity of moisture content during drying is doubly disadvantageous. Moisture nonuniformity reduces drying effectiveness, increasing drying cost or reducing drying capacity, and may decrease product quality for printing through effects such as cockling and curl. These problems can occur with the now dominant process of cylinder drying, but become much more acute with the various higher intensity drying techniques which are competing to become elements of the higher speed hybrid dryer sections of the future. For quantitative characterization of moisture nonuniformity a novel method applicable to paper being dried by various processes was developed, then demonstrated for one high intensity air convection process, through air drying. During drying, the local moisture content was determined for many 2.5 mm diameter sensing areas by very rapid scanning with a custom design 3-wavelength infrared paper moisture instrument. For local moisture nonuniformity thus determined, the coefficient of variation provides a standard basis for comparison between paper types and drying conditions. For kraft paper from 20 to 120 g/m², the effects on local moisture nonuniformity were evaluated for drying intensity and for several paper parameters—formation, grammage, and initial moisture content. The drying nonuniformity index was found to parallel both formation quality and drying intensity. An unexpected finding was that over the 20-120 g/m² range, local moisture nonuniformity passes through a maximum at 30 g/m². Sheet initial moisture content produces the largest effect, with moisture nonuniformity index being both high and very sensitive to this parameter for initial moisture content above the fibre saturation point. Another finding from these unique measurements is that, for the same 2.5 mm diameter sensing areas, there is a clear correlation between moisture nonuniformity index and local grammage.     

Moisture Nonuniformity in Drying Paper: Measurement and Relation to Process Parameters

Abstract

Local nonuniformity of moisture content during drying is doubly disadvantageous. Moisture nonuniformity reduces drying effectiveness, increasing drying cost or reducing drying capacity, and may decrease product quality for printing through effects such as cockling and curl. These problems can occur with the now dominant process of cylinder drying, but become much more acute with the various higher intensity drying techniques which are competing to become elements of the higher speed hybrid dryer sections of the future. For quantitative characterization of moisture nonuniformity a novel method applicable to paper being dried by various processes was developed, then demonstrated for one high intensity air convection process, through air drying. During drying, the local moisture content was determined for many 2.5 mm diameter sensing areas by very rapid scanning with a custom design 3-wavelength infrared paper moisture instrument. For local moisture nonuniformity thus determined, the coefficient of variation provides a standard basis for comparison between paper types and drying conditions. For kraft paper from 20 to 120 g/m², the effects on local moisture nonuniformity were evaluated for drying intensity and for several paper parameters—formation, grammage, and initial moisture content. The drying nonuniformity index was found to parallel both formation quality and drying intensity. An unexpected finding was that over the 20–120 g/m² range, local moisture nonuniformity passes through a maximum at 30 g/m². Sheet initial moisture content produces the largest effect, with moisture nonuniformity index being both high and very sensitive to this parameter for initial moisture content above the fibre saturation point. Another finding from these unique measurements is that, for the same 2.5 mm diameter sensing areas, there is a clear correlation between moisture nonuniformity index and local grammage.     

碳酸盐胶结物与富县探区延长组长8油层组的关系

通过薄片的观察鉴定,样品的扫描电镜测试分析,并结合一些测井资料及常规的实验分析,对鄂尔多斯盆地富县探区延长组长8段砂岩的碳酸盐胶结特征进行研究,合理解释碳酸盐胶结物在砂岩的分布规律以及在成岩阶段中的作用,为寻找低孔低渗砂岩中的有利储层及后续油气开发提供重要依据.     

硫氰酸钠法高吸湿(水)腈纶纺丝工艺及其性能的研究

采用丙烯酸和丙烯腈的共聚物与聚丙烯腈共混纺丝的方法,纺制了丙烯酸改性的聚丙烯腈纤维,研究了纺丝工艺条件与改性腈纶性能之间的关系。实验结果表明:随着共混纺丝所采用的丙烯酸共聚物的共聚比的增加,改性腈纶的断裂强度有所下降,吸湿性和保水性则不断提高;采用低温干燥致密化和较低的总拉伸倍数,有利于提高改性纤维的吸湿和保水性能;随着纤度的增大,改性腈纶的回潮率和保水率渐渐减小。     

聚丙烯接枝马来酸酐增容聚酰胺6／聚丙烯体系吸湿性能及力学性能的研究

以聚丙烯接枝马来酸酐(PP-g-MAH)为相容剂，利用其与聚酰胺6(PA6)在共混过程中的反应增容作用，实现了与聚丙烯(PP)之间的相容性共混，改变其用量，制备了系列具有不同组成的PA6／PP合金，研究了不同组成合金材料的吸湿性能及其在干态和充分吸湿状态时的冲击强度和拉伸性能。结果表明，向PA6／PP合金体系中加入相容剂PP-g-MAH后，可以改善合金的相界面，形成相容性的合金结构，明显降低合金材料的吸湿量及吸湿速率，但进一步增大相容剂PP-g-MAH的用量时，只能明显降低合金材料吸湿过程初期的吸湿速率，不能进一步显著降低合金材料的吸湿量。在相容剂PP-g-MAH用量一定时，随着PA6／PP合金体系中PA6组分含量的提高，合金在干、湿态条件下的冲击强度、拉伸强度、断裂伸长率均呈近似线性变化。对于具有相同基本组成的合金，随着相容剂PP-g-MAFI用量的增加，材料在干、湿态条件下的拉伸强度均有提高，杨氏模量则在干态时有所提高，在湿态时影响不显著，在干、湿态时断裂伸长率以及冲击强度均没有产生显著影响。     

不同织物上吸湿排汗整理剂的合成与应用进展

文章对不同织物上吸湿排汗整理剂的合成方法和应用原理进行阐述。综述了涤纶、锦纶上所使用吸湿排汗整理剂的合成方法及应用,并对其他天然纤维、合成纤维及其混纺织物上所使用吸湿排汗整理剂的合成方法与应用进行展望。     

Morphology and Properties in Blended Cements with Ceramic Wastes as a Pozzolanic Material

This paper describes the research run on ceramic materials, and more specifically fired clay roof tiles, ground to a fineness suitable for use as an active replacement for portland cements (PCs). The utilization of waste products from calcined clay roof tiles as a pozzolanic material in the cement manufacture is studied. One of the first materials used as pozzolans in the history was thermal-treated clay, a material similar to the calcined clay precast elements. For this study, the materials selected are clay products that have been eliminated for different reasons: a wrong temperature inside the kiln, dimensional and mechanical failures, and durability loss. The results showed that these products have good pozzolanic properties; at an early age, the pozzolanic activity was found to be higher than fly ash, although it was lower than silica fume. The morphology of clay tile–PC pastes are similar to the morphology of the pastes containing other pozzolanic materials. Hydrated calcium aluminate products are generated when the preparation method yields less compact pastes with a greater voids' volume to accommodate these products. The hydrated calcium aluminate phases were analyzed using scanning electronic microscopy and X-ray diffraction techniques.