覆铜板用低分子量双端羟基聚苯醚树脂

低分子量α,ω-双(2,6-二甲基羟苯基)聚苯醚(PPO-2OH)具有优异的电性能和耐热性能,改性后的热固性聚苯醚树脂是高性能覆铜板的理想基材之一。介绍了低分子量PPO-2OH的合成方法和热固化改性研究过程,概述了近几年低分子量PPO-2OH针对覆铜板应用的研究进展。     

面向超高频通信应用的低介电聚苯醚树脂的研究进展

本文综述了聚苯醚树脂在超高频低介电领域进行的一系列制备与改性研究工作,包括低分子量聚苯醚的制备、化学结构改性、与其他树脂复合、无机/有机杂化等,然后对低介电聚苯醚树脂目前存在的问题进行总结,并对其未来发展趋势进行了展望。     

低分子量聚苯醚改性氰酸酯树脂的研究

采用低分子量聚苯醚(SA90)对氰酸酯(CE)进行改性,并在混合催化剂二月桂酸二丁基锡(DBTDL)和2-乙基-4-甲基咪唑(2E4MI)的作用下,制备了一种改性氰酸酯树脂。研究了SA90含量对改性氰酸酯树脂凝胶化时间、变温拉伸剪切强度、平面应变断裂韧性、介电性能和吸水率的影响。结果表明:随着SA90含量的增加,改性氰酸酯树脂的凝胶化时间逐渐缩短,活化能均在50～70 k J/mol,反应活性较高;当SA90的质量分数为20%时,改性氰酸酯树脂的整体拉伸剪切强度最大;断裂韧性随着SA90含量的增加先增大后减小,当SA90的质量分数为20%时,改性氰酸酯树脂的断裂韧性最佳;适量添加SA90能改善氰酸酯的介电性能以及吸水率。     

溶剂热法制备多层结构Co_3O_4及其超电容特性

以硝酸钴为原料,溴化十六烷基三甲胺(CTAB)为分散剂,尿素为沉淀剂,采用混合溶剂热法制备了Co_3O_4。研究了水-正丁醇、水-正戊醇-正己烷、水-正丁醇-正己烷三种不同溶剂体系下对Co_3O_4超电容性的影响。通过交流阻抗、循环伏安、恒流充放电对Co_3O_4电极材料的电化学性能进行表征,结果表明,不同溶剂对其电化学性能有显著影响,在水-正丁醇-正己烷的溶剂体系中,反应温度为100℃时得到的Co_3O_4电极材料具有较好的电化学性能,在6 mol/L KOH溶液中,电流密度为5 mA/cm~2时,其单电极放电比电容达667.7 F/g。     

高频应用的聚苯醚树脂基基材

本文介绍了新一代高频应用的聚苯醚树脂基覆铜板的出现、发展及性能;简要综述了聚苯醚／环氧共混物合金和热固性聚苯醚两种树脂体系的特性和覆铜板的性能。     

高压开关锂电池壳体用MPPIFR材料的阻燃性能研究

作为高压开关电池内外承压的介质,外壳的阻燃性能在发生危险状况时对电池的安全防护有重要的作用。将聚苯醚、聚丙烯和增溶剂功能性丙烯酸缩水甘油酯接枝根据一定的比例混合,制备改性聚丙烯(MPP),将聚磷酸铵、三聚氰胺氰尿酸盐根据一定的比例混合,制备膨胀型无卤阻燃剂(IFR),将改性聚丙烯(MPP)与膨胀型无卤阻燃剂(IFR)按多种质量比共混,制备实验样品MPP/IFR,进行垂直燃烧实验。对阻燃性能、力学性能、微观形貌等性能进行分析。     

谈水涂工艺的涂层

谈水涂工艺的涂层■戴允礼朱健民／常州照明电器厂一、水涂粉新工艺的特点在荧光灯用材料的技术进步中,用水溶性粘接剂代替丁酯溶剂粘接剂的涂粉工艺是最值得称道的。水涂粉工艺有明显的三大优点：首先是安全性,不象丁酯、硝棉易燃、易爆;其次是改善了工人的劳动环境,...     

国内文摘与专利

<正>高压绝缘用PA66复合材料的性能研究/任洛卿;张永刚;周柏杰/塑料科技,2015(8)针对电力行业对高压用绝缘材料的性能要求,开展了几种热塑料绝缘材料(聚酰胺66(PA66)复合材料,聚苯醚(PPO)     

超滤技术及其在电泳工艺上的应用

一、超滤与超滤膜 1.超滤法的定义 划分过滤设备等级,一个既方便而又可行的办法是看分离粒子的大小,而超滤法就是应用于分离10~(-1)～10~(-3)微米范围内的粒子的一种方法。因此,所谓超滤并非一般所公认的真的过滤,而只能说是一种分离作用,将水和低分子量的溶质、盐、溶剂等,从含水的涂料溶液中分离出来,之所以能够“分离”,是因     

Li/KIBr_2非水体系的研究

本文介绍的非水电池体系由锂阳极,多孔石墨电极和电解质溶液构成,电解质溶液由非水溶剂(三氯氧磷或硝基苯)和溶解在该溶剂中的活性物质(KIBr_2)及电解质构成,该电池体系具有较高的开路电压(3.5V)和良好的放电性能。作者对该电池的电化学还原行为作了初步的探讨。     

电解液添加剂对金属锂电极的表面改性

为了提高金属锂二次电池中锂电极的性能,在电解液中添加了不同比例的1,4-二氧六环,测试了Li-LiCoO2扣式电池的性能。结果表明,在电解液中添加质量分数2%的1,4-二氧六环可使锂电极循环寿命大大增加,利用率增加10%,放电平台提高约100mV。与用1,4-二氧六环进行表面预处理电池相比,利用率和循环寿命差不多,但高次循环的放电平台可增加约80mV。而且,添加质量分数2%的1,4-二氧六环后电池的大电流放电性能也较好。     

Effects of moisture on the dielectric properties of polyoxymethylene (POM)

The effects of absorbed water on the gamma-relaxation process of polyoxymethylene (POM) were studied using dielectric spectroscopy and thermogravimetric analysis. The spectra were measured isothermally over the frequency range of 10 MHz to 2 GHz, and the water content was varied from dried to 1.65 wt% (saturated). The strength and rate of the gamma-relaxation process increased with increasing water content, contradicting earlier studies that found this process to be relatively insensitive to changes in the molecular environment. Two different formalisms that express the fraction of contributing water dipoles to the measured spectra were compared using the experimental data. The results of the two expressions differed by approximately 20% in their estimation of unbound, participative water and both suggest that the water relaxation process is slowed for the absorbed water in comparison to free, or bulk, water. The shift in the measured spectra for the water/POM system is attributed to the steric hindrances imposed on the water molecules by the hydrogen bonds formed with the polymer molecules. The effects of water sorption by POM were used to derive the associative effects on antenna performance for a hypothetical microstrip antenna comprised of a dielectric layer of POM. It was found that the resonant frequency decreased by 7.5% for a water uptake of 1.65 weight percent     

Ferroelectric thin film research in france

Abstract

After a review of the research made on thin film deposition in France, this work presents the comparison between two chemical deposition methods for PZT films: sol-gel method based on low molecular weight precursors and solvent, and MOD (Metallo-Organic Deposition) process based on a hydrophobic solvent. The influence of the viscosity of the solvent and of the solubility of water is shown with regard to stability and drying properties. The final electrical properties of the ferroelectric films are also compared such as the hysteresis loop which characterizes the most important properties for memory application: coercive voltage and rectangularity.     

Photocatalytic property of SiO2/TiO2 nanoparticles prepared by sol-hydrothermal process

Silica-embedded nanocrystalline TiO₂ powders were synthesized by sol-hydrothermal process. The influence of the composition of the solvent and the embedded silica content on the phase transition, grain growth and subsequently, on the photoactivity of TiO₂ were investigated. The volume ratio of ethanol to water for the solvent composition was varied from 0.125 to 8 and the mole fraction of silica content was changed from 0 to 0.4, while the condition for hydrothermal reaction was fixed at 250^∘C for 2 hour. With an increase in ethanol content in solvent composition, the crystallite sizes of pure TiO₂ particles decreased from 15 nm to 6 nm and crystal phase changed from rutile/anatase mixed phase to pure anatase phase. Addition of silica to TiO₂ brought about an increase in the photocatalytic activity by suppressing the phase transition from anatase to rutile. Judging from the result of the decomposition of 1, 4-dichlorobenzene, the most efficient catalyst was found to be 0.2 mole fraction SiO₂ embedded TiO₂ prepared with ethanol-rich solvent (the volume ratio of ethanol to water is 4).     

Size-controllable barium titanate nanopowder synthesized via one-pot solvothermal route in a mixed solvent

Barium titanate nanopowder was synthesized via solvothermal route using water-ethanol-ethylene glycol monomethyl ether as mixed solvent and TiCl₄-Ba(OH)₂ · 8H₂O as precursors. The effects of water amount in a mixed solvent, synthetic temperature and reaction time on microstructure and particle size of the as-prepared barium titanate powder were investigated systematically. The results show that the particle size of barium titanate powder could be tuned by varying the synthetic parameters. The procedure presented here provides a simple route to the preparation of barium titanate nanopowder with controllable particle size.     

Electrical and chemical diagnostics of transformers insulation. A.Aged transformer samples

This paper describes the application of two relatively new diagnostic techniques for the determination of insulation condition in aged transformers. The techniques are: (a) measurements of interfacial polarization spectra by a DC method; and (b) measurements of molecular weight and its distribution by gel permeation chromatography. Several other electrical properties of the cellulose polymer were also investigated. Samples were obtained from a retired power transformer and they were analysed by the developed techniques. Six distribution transformers were also tested with the interfacial polarization spectra measurement technique, and the molecular weight of paper/pressboard samples from these transformers were also measured by the gel permeation chromatography. The variation of the results through different locations in a power transformer is discussed in this paper. The possible correlation between different measured properties was investigated and discussed in this paper     

溶剂、非溶剂对干法制备聚合物隔膜的影响

采用相转化法(干法)制备了聚合物锂离子蓄电池用隔膜。通过扫描电镜对隔膜形貌进行分析,研究了在干法制膜过程中溶剂和非溶剂对隔膜形貌和性质的影响。采用交流阻抗技术测定了隔膜的电导率;以丙酮作溶剂、水为非溶剂制备的隔膜具有良好的电化学性能,吸液率高达375%。用其装配电池,首次充放电效率88.3%,第五周可达99.4%。     

新型含六氟环丁基类聚合物的设计、合成及表征

利用1,2-二(4-乙炔基苯氧基)全氟环丁烷含氟单体与双叠氮芳基化合物通过“点击化学”合成了一类含六氟环丁基和1,2,3-三氮唑环结构的新型含氟高分子聚合物.结果表明:此类含氟聚合物具有良好的溶解性、较窄的分子量分布和优异的热稳定性,有望被用作耐高温材料.     

Li|SPE|Li体系阻抗谱分析

为了深入研究对称锂金属电极聚合物电池的界面特性,以PEO为基质,并复配少量纳米无机填料及低分子乙氧化物,制备了固态纳米复合聚合物电解质膜,组装成对称锂金属电极模拟电池,利用交流阻抗法进行测试,并设计出等效电路对测试数据进行拟合,通过数学推导确定了各元件在复数平面图上的对应位置.该等效电路对PEO基固态聚合物电解质体系具有非常好的拟合效果.     

溶剂选择对P(MMA-Vac)聚合物电解质性能的影响

利用乳液聚合法合成了新型聚甲基丙烯酸甲酯-醋酸乙烯酯P(MMA-Vac),以此共聚物制备了聚烯烃多孔膜支撑的凝胶聚合物电解质膜,用扫描电镜(SEM)、差热分析仪(DTA)、交流阻抗(AC)、电池充放电实验等方法比较了该共聚物在丙酮和N-N二甲基甲酰胺(DMF)中溶解成膜后的行为。结果表明:以DMF为溶剂制得到的聚合物膜具有较高的吸液率,制得的聚合物电解质有良好的离子传输性能和电池性能,比丙酮用作溶剂的效果更好。