配合胶乳和硫化胶乳胶膜干燥历程及交联密度比较研究

采用热风干燥方法进行配合胶乳和硫化胶乳胶膜的干燥实验,研究了两种天然胶乳胶膜的千燥动力学过程及干燥过程与橡胶分子链交联密度的关系。结果表明,配合胶乳膜干燥的活化能Ea1=314kJ·mol^-1,硫化天然胶膜的干燥活化能Ea2=63．6kJ·mol^-1,配合胶乳膜较硫化胶乳膜易于干燥;在相同条件下,配合胶乳膜的交联密度始终低于硫化胶巍膜。配合胶乳膜和硫化胶乳膜的干燥过程与硫化过程并不同步,过度的加热干燥会导致交联密度的降低。     

天然胶乳厚胶膜热风干燥与红外干燥对比研究

采用失重法研究了天然胶乳厚胶膜在热风与红外线两种干燥方式下的干燥过程。研究结果表明,在相同条件下,红外干燥的干燥速率常数远大于热风干燥,采用红外干燥可大大缩短干燥时间,干燥温度和厚度均显著影响干燥过程,红外干燥对温度更敏感。通过动力学拟合结果,得到了干燥动力学方程,可以预测干燥时间。     

含油污泥干燥处理技术

干燥技术处理含油污泥．已经成为国内外石油化工行业的研究热点。先简要介绍了含油污泥的来源,又着重介绍了干燥技术的主要工艺流程,指出利用干燥技术对含油污泥实现无害化和资源化,具有可资源化利用、不产生二次污染等优点,是国内外含油污泥处理处置的发展趋势。     

硫酸干吸工序串酸自控方案的可行性分析与优化

介绍了硫酸干吸工序的串酸机理和自动控制流程,理论分析结果表明,四套可行方案均能利用酸浓和液位参数对干吸系统的串酸量和产酸量实施自动控制,依据实际情况进一步比较优劣,阐述了最为简单直接且易于操作的控制方案.     

Modular process for the flexible synthesis of magnetic beads—Process and product validation

Here we present a modular process for the flexible production of magnetic beads with variable magnetic properties and anion or cation exchanger functionalities. Magnetic beads are used in bio‐separations and downstream processing to remove a valuable substance from e.g., a fermentation broth (Magnetic Fishing). The magnetic beads we are presenting here consist of a composite material, containing nanoscale magnetite and ion exchanger particles which are embedded into a polymer matrix. With this composite concept, anion and cation exchanger properties are available in magnetic beads with different matrix polymers (PVB, PVA, PMMA, and PVAc). The content of magnetite was varied in a range between 0 and 40 wt %, ion exchanger particles between 0 and 60 wt % and the matrix polymer between 20 and 60 wt %. The magnetic bead characteristics, which determine the application properties, are shown. Thermo gravimetrical analyses, FTIR spectra and measurements of the ion exchange capacity prove the different properties in respect to the magnetic beads composition. In an adsorption experiment, it was possible to achieve a maximum capacity of 270 mg/g for β‐galactosidase with PVB‐beads. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

超临界流体技术在催化剂制备方面的应用

超临界流体技术是近年来发展起来的新技术。对超临界流体技术的特点及在催化剂制备方面的应用进行了概述。介绍分析了超临界流体干燥技术、超临界流体造粒技术、超临界流体模板和超临界流体沉积技术的技术原理、特点和研究进展。并在此基础上总结了超临界流体在催化剂制备方面的发展方向和今后研究工作的重点。     

混凝土施工过程开裂的原因及预防措施

本文对施工过程中容易引起混凝土开裂的原因进行了总结,从理论和实践的角度进行了分析,并针对问题提出了预防措施和处理办法。这对施工中避免工程质量问题和工程质量通病的发生具有一定的借鉴意义.     

浅谈工程施工中粘土层的快速锚固技术

更多的建设工程项目基础会遇到粘土层,而粘土层中的地质情况复杂多变,增加了深基础施工的难度,提高施工效率而采用快速锚固技术是解决这一问题的重要手段。文章就快速土层锚杆的应用谈点体会。     

MPC-EPS轻质混凝土性能试验研究

以磷酸镁水泥(magnesium phosphate cement,MPC)为胶凝材料制备出了表观密度为1 800～750 kg/m~3的可用于结构的磷酸镁水泥-聚苯乙烯泡沫(MPC-EPS)混凝土.试验研究了MPC-EPS混凝土的力学性能、干缩性能、吸水率及抗冻融和干湿循环能力.结果表明:MPC-EPS混凝土具有较高的早期强度,且EPS掺量越大,其早期强度发展越快;与普通水泥为胶凝材料的EPS混凝土相比,MPC-EPS混凝土具有较低的干缩变形和吸水率,是一种耐久性良好的保温隔热材料.     

Using a new diffusivity model to accelerate the drying of biopolymer films

A model was developed to study the drying rate of biopolymer films. The diffusivity of water in this biopolymer film is an exponential function of the water concentration. This creates a situation where simply increasing gas velocity can decrease the actual drying rate. The model revealed that the main factor limiting the drying of the biopolymer film was a significant and rapid decrease in the diffusivity of water through the film as the film dried. To avoid this a pulsing scheme was proposed where the velocity of the drying gas would be varied during the experiment; this variation allowed for a compromise between a high overall drying rate and maintaining a high diffusivity within the film. It was found that the optimum combination of gas velocities was 0.8 and 0.6 m/s with a duration of 10 min at the high and low gas velocities.