LIQUID PHASE TRANSPORT PROPERTIES IN A HIGH PRESSURE PACKED COLUMN

A mathematical model of fluid flow and mass transfer in a packed bed was derived and used to evaluate the liquid phase axial dispersion and mass transfer coefficients under high pressure conditions. The least-squares method was used to evaluate the rate parameters from experimental breakthrough curves, and the agreement between the concentration curves predicted from rate parameters and those measured experimentally was good. Experiments were performed at 20 and 200°C with water as a solvent and nonporous soda-lime glass beads as packing. Although the axial dispersion coefficient was independent of temperature and pressure, the mass transport parameters were found to be pressure dependent.     

歧化松香钾皂制备方法的改进与性能研究

以歧化松香为主要原料,在较低的温度(75~95℃)下,溶入KOH水溶液,并进行皂化反应,制备固体份质量分数45%的歧化松香钾皂。研究了反应温度、皂化时间、pH值、添加复合助剂TX-A对反应速度、去氢枞酸钾含量,以及黏度、结晶、胶凝等产品性能的影响。得出歧化松香钾皂化的较佳制备条件为:pH值为10.36,皂化时间分别为120 min(未加TX-A)、98 min(加TX-A),反应温度85℃,TX-A加入量为反应物质量的0.2%。制备出的歧化松香钾皂产品,在性能上完全符合行业标准ZBB 72003-84的要求,并且结晶、胶凝性质有所改善,加纳色号标准降低两个等级。     

0.3%印楝素乳油防治水稻二化螟药效试验

0.3%印楝素乳油对水稻二化螟有较好的防治效果,用药后14 d防效达90%左右,而且对稻株无药害,可以作为当前防治二化螟的选择药剂。     

复合材料弹道冲击性能研究进展

本文总结了近年来复合材料弹道冲击研究的进展,着重从纤维集合体的结构对弹道冲击损伤机理的影响、弹道冲击的分析模型及数值模拟做了概述,总结了人们为提高复合材料弹道冲击性能所做的努力,最后指出了几个尚需深入解决的问题.     

Synthesis and characterization of butan‐1‐ol modified toluene diisocyanate trimer

Butan‐1‐ol modified toluene diisocyanate tri mer (TDI‐trimer) was synthesized and characterized with Fourier transform infrared spectroscopy, gel permeation chromatography, and thermal gravimetry analysis techniques. The modified TDI‐trimer showed good dissolvable ability with hydroxy resin and can be used to produce paints with acrylic polyol resin. The thermal stability of the modified TDI‐trimer was improved by simply increasing both the amount of catalyst and the ratio of ? NCO/? OH, less depended on the kind of catalyst. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 4958–4962, 2006     

Preparation and morphology of electrically conductive and transparent poly(vinylchloride)-polypyrrole composite films

Summary The chemical process of preparing poly(vinylchloride)-polypyrrole composite films with high electrical conductivity and transparency has been studied. Pyrrole has been diffused into the poly(vinylchloride) matrix in the swelling medium of n-hexane and acetone mixture. The oxidative polymerization of the diffused pyrrole in the binary solvent system of acetonitrile and methanol gives high conductivity of the polypyrrole as well as the good penetration of the oxidant into the PVC polymer matrix. The analytical testing of the composite film shows the formation of homogeneous mixture of polypyrrole and poly(vinylchloride) conductive layer within the 1.0m of thickness on the film surface. The transparency of the composite film showed about 50–60% at 500 nm. The electrical conductivity of the composite was about 20 s/cm.     

硝酸尾气中NOx测定方法的探讨

1概述 硝酸尾气主要由以下成分组成：少量NOx、93％的N2、3％～5％的O2、惰性气体和硝酸蒸汽。我公司原采用酸碱滴定法测定硝酸尾气中的NOx含量，即用过量氢氧化钠溶液吸收尾气中的NOx，然后用硫酸标准溶液返滴剩余氢氧化钠，由此计算出尾气中的NOx含量。但此法存在很大的弊端：一是将尾气中的硝酸蒸汽当作NOx一起分析，造成分析结果偏高；二是分析误差较大；三是用真空瓶采样，受负压、采样温度、采样装置气密性等因素影响，再现性较差。经过试验后，认为采用盐酸萘乙二胺分光光度法检测硝酸尾气中的NOx含量较好。此法操作简便、干扰少、灵敏度较高，精度和准确度都较高，是目前较理想的检测硝酸尾气中NOx含量的方法。     

Encapsulation mechanism of N2 molecules into the central hollow of carbon nitride multiwalled nanofibers

Nitrogen molecules have been encapsulated into the central hollows of vertically aligned carbon nitride (CN) multiwalled nanofibers by dc plasma-enhanced chemical vapor deposition with C₂H₂, NH₃, and N₂ gases on a Ni/TiN/Si(1 0 0) substrate at 650 °C. X-ray photoelectron spectroscopy and near-edge X-ray absorption fine structure spectra showed the existence of nitrogen molecules in CN nanofibers. Elemental mapping images with electron energy loss spectroscopy of the CN nanofiber and catalyst metal, and optical emission spectroscopy spectra of the plasma showed the distribution of nitrogen atoms and molecules in the CN nanofiber, catalyst metal, and gaseous precursor, respectively. These studies showed that atomic nitrogen diffused into the catalytic metal particle because of the concentration gradient and then saturated at the bottom of the particle. Saturated nitrogen atom participated in the formation of the CN nanofiber wall but most of nitrogen was trapped in the central hollow of the nanofiber as molecules.     

Synthesis and non‐isothermal crystallization behavior of poly(ethylene phthalate‐co‐terephthalate)s

A series of poly(ethylene phthalate‐co‐terephthalate)s were synthesized by melt polycondensation of ethylene glycol (EG) with dimethyl phthalate (DMP) and dimethyl terephthalate (DMT) in various proportions. The DMT‐rich polymers were obtained with reasonably high molecular weights, whereas the DMP‐rich polymers were synthesized with relatively low molecular weights due to steric effects associated with the highly kinked DMP monomer. The compositions and thermal properties of the polymers were determined. The copolymers containing DMP in amounts of ≤ 21 mol% were crystallizable, whereas the other polymers were not. All the polymers exhibited a single glass transition temperature. Analysis of the measured glass transition temperatures and crystal melting temperatures confirmed that the DMT‐rich copolymers are random copolymers. The non‐isothermal crystallization behaviors of the DMT‐rich copolymers were investigated by calorimetry and modified Avrami analysis. The Avrami exponents n were found to range from 2.7 to 3.8, suggesting that the copolymers crystallize via a heterogeneous nucleation and spherulitic growth mechanism; that is, the incorporation of DMP units as the minor component does not change the growth mechanism of the copolymers. In addition, the activation energies of the crystallizations of the copolymers were determined; the copolymers were found to have higher activation energies than the PET homopolymer. Polym. Eng. Sci. 44:1682–1691, 2004. © 2004 Society of Plastics Engineers.     

Preparation and characterization of maleic anhydride‐g‐polypropylene/diamine‐modified clay nanocomposites

Polypropylene (PP)/montmorillonite (MMT) nanocomposites were prepared by compounding maleic anhydride‐g‐polypropylene (MAPP) with MMT modified with α,ω‐diaminododecane. Structural characterization confirmed the formation of characteristic amide linkages and the intercalation of MAPP between the silicate layers. In particular, X‐ray diffraction patterns of the modified clay and MAPP/MMT composites showed 001 basal spacing enlargement as much as 1.49 nm. Thermogravimetric analysis revealed that the thermal decomposition of the composite took place at a slightly higher temperature than that of MAPP. The heat of fusion of the MAPP phase decreased, indicating that the crystallization of MAPP was suppressed by the clay layers. PP/MAPP/MMT composites showed a 20–35% higher tensile modulus and tensile strength compared to those corresponding to PP/MAPP. However, the elongation at break decreased drastically, even when the content of MMT was as low as 1.25–5 wt %. The relatively short chain length and loop structure of MAPP bound to the clay layers made the penetration of MAPP molecules into the PP homopolymer phase implausible and is thought to be responsible for the decreased elongation at break. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 95: 307–311, 2005