同时考虑流动损费和传热强化的换热网络合成

详细论证了在求解换热网络优化狭点温差△T_mtn,opt过程中,同时考虑换热器流动(火用)损、匹配单元优化和传热强化的必要性.提出以“Supertargeting”所给出的最优狭点温差为初值向狭点温差增大的方向寻求最优解的方法.文中对影响△T_min,ovt大小及其与初值之差的经济条件和复合线特性进行了讨论;提出了新的换热网络优化合成策略.用3个实例来说明所提出方法的优越性.     

聚甲基丙烯酸甲酯／镉黄颜料色母粒的合成及其研究

采用亚硫酸氢钠、过氧化二苯甲酰作引发剂,在无机镉黄颜料水悬浮液中,引发甲基丙烯酸甲酯进行聚合反应,得到了镉黄颜料色母粒。对该种色母粒作了红外光谱及DTA、TG分析,并探讨了其反应机理。     

铋基烧绿石陶瓷及其微波特性

介绍了低烧结温度的铋基烧绿石系介质陶瓷的结构特点和微波响应行为。以铋基烧绿石中典型的Bi2O3-ZnO-Nb2O3系及其四元系固溶体陶瓷为例，详述了这些体系的相结构、相变及其改变其微波介电性能的途径。指出低烧结温度的铋基烧绿石系介质陶瓷的基本实验制备工艺与检测技术，并讨论了进一步降低烧结温度的方法，对其今后的发展进行了展望。     

无氨耐燃烧酚醛注塑料的研究与应用

介绍无氨耐燃烧酚醛注塑料的制备、成型条件和性能。该注塑料耐漏电起痕指数高,阻燃性能优异,使用中不释放氨,从而不腐蚀电器、仪表金属嵌件和电气触头,是精密电器、仪表的关键材料,成功用于冰箱压缩机过载保护器外壳。     

Thermal and optical properties of PMMA–titania hybrid materials prepared by sol‐gel approach with HEMA as coupling agent

A series of sol‐gel derived organic–inorganic hybrid materials consisting of organic poly(methyl methacrylate) (PMMA) and inorganic titania (TiO₂) were successfully synthesized by using 2‐hydroxyethyl methacrylate (HEMA) as coupling agent. In this work, HEMA is first copolymerized with methyl methacrylate monomer at specific feeding ratios by using benzoyl peroxide (BPO) as initiator. Subsequently, the as‐prepared copolymer (i.e., sol‐gel precursor) is then cohydrolyzed with various contents of titanium butoxide to afford chemical bondings to the forming titania networks to give a series of hybrid materials. Transparent organic–inorganic hybrid materials with different contents of titania are always achieved. Effects of the material composition on the thermal stability, optical properties, and morphology of neat copolymer and a series of hybrid materials, in the form of both coating and free‐standing film, are also studied by differential scanning calorimetry, thermogravimetric analysis, UV–Vis transmission spectra, refractometer, and atomic force microscopy, respectively. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 400–405, 2004     

Simultaneous recovery of Pb and PbO2 from battery plant effluents. Part II

Results are reported of experiments and modelling of cathodic Pb and anodic PbO₂ electrodeposition, aimed at developing a process using both reactions simultaneously for treating aqueous effluents from lead–acid battery recycling plants. Pb(II) solubilities and equilibrium potentials were calculated as functions of pH and sulfate activities. Using kinetic parameters from the literature or determined experimentally, models were developed for current density–potential and current efficiency–potential relationships, together with the current density dependence of specific electrical energy consumptions for Pb(II) recovery. Experimental current density–potential and charge efficiency–potential relationships were in broad agreement with model predictions, with near unity current efficiencies for mass transport controlled PbO₂ deposition from electrolytes containing 1 mol Pb(II) m^–3 at pH 12. However, charge efficiencies for cathodic deposition of lead were typically 0.2 for 1 mol Pb(II) m^–3 + 1 mol O₂ (aq) m^–3; removal of dissolved oxygen was predicted and determined to increase current efficiencies to near unity. Pb(II) concentrations were depleted to <60 ppb in a batch recycle reactor system with graphite felt anodes and graphite or titanium felt cathodes. Simultaneous cathodic Pb and anodic PbO₂ electrodeposition resulted in more rapid Pb(II) depletion than for either reaction separately.     

Preparation of Fully Imidized Hyperbranched Photosensitive Polyimide with Excellent Organosolubility and Thermal Property Based on 4,4'-(Hexafluoroisopropylidene) Diphthalic Anhydride (A<Subscript>2</Subscript>) and 1,3,5-Tris(4-aminophenoxy)benzene (B<Subscript>3</Subscript>)

Summary A negative-tone hyperbranched photosensitive polyimide (HB-PSPI) based on a new triamine, 1,3,5-tris(4-aminophenoxy)benzene (TAPOB), and 4,4'-(hexafluoroisopropy1idene)diphthalic anhydride (6FDA) was synthesized. The photosensitive cinnamate groups were incorporated at the periphery of thepolymer by the reaction of cinnamoyl chloride with the terminal phenol groups of the fully imidized hyperbranched polyimide, which was obtained via the end group modification of the anhydride-terminated hyperbranched poly(amic acid) precursor. The polymer showed good thermal property with 10 wt % loss temperature at 517 °C, and exhibited excellent organosolubility even in acetone and 1,1,2-trichloroethane. Photolithographic property of the polymer was examined by UV exposure. SEM analysis revealed that highly resolved patterns with a line width of 10 pm were obtained; and well-defined line as thin as 3pm in width could be patterned, though the line edges were jagged and rounded due to the broad molecular weight distribution. Received: 8 August 2002/Revised version: 10 October 2002/ Accepted: 26 November 2002 Correspondence to Jie Yin     

聚氯乙烯／蒙脱土复合材料的结构与性能研究

采用熔融共混法制备得到PVC／蒙脱土复合材料。通过X射线衍射和透射电镜对复合材料的结构进行了表征。研究了钠基蒙脱土和烷基季铵盐改性的有机蒙脱土对聚氯乙烯／蒙脱土复合材料的结构、加工热稳定性、光学性能、力学性能和结构流变性能的影响。     

铬、钴、铁用作彩色渗花砖发色元素的研究

用晶体体场理论讨论了铬、钴、铁作为陶瓷发色元素的呈色机理，并对彩色渗花液在砖坯上的渗入过程及物理化学原理进行了研究，分析了影响发色剂呈色的主要因素。     

Formation and inhibition of free radicals in electrically stressed and aged insulating polymers

Previous work has shown that prebreakdown, electrical aging, and breakdown phenomena are directly associated with charge carriers injected from electrical contacts and their subsequent dissociative trapping and recombination. In addition, the energy released from each trapping or recombination event is dissipated in the breaking of the bonds of macromolecules, thus forming free radicals and new traps in the electrically stressed insulating polymers, as predicted by Kao's model. It is this gradual degradation process that leads to electrical aging and destructive breakdown. New experimental results are presented to confirm previous findings and a new approach to inhibit the degradation process by the incorporation of suitable dopants into the polymer. The concentration of free radicals in the polymer increases with an increasing electric field at a fixed stress time of 250 h and with increasing stress time at a fixed electric field of 833 kV cm^?1. The concentration of free radicals is directly related to the concentration of new traps created by stress. However, when suitable dopants are incorporated, the initiation voltage for the occurrence of electrical treeing and the breakdown strength are both increased. The dopants tend to create shallow traps and have little effect on the deep trap concentration. This implies that the dopants act as free‐radical scavengers that tend to satisfy the unpaired electrons of the broken bonds, which create new acceptor‐like electron traps and new shallow traps. By doing so, the shallow traps screen the deep traps, thereby reducing the energy released during trapping and recombination and the probability of breaking the macromolecular bonds and causing structural degradation. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 3416–3425, 2003