石墨烯/硫酸铅复合材料的制备及其在铅酸电池中的电化学性能

利用简单的浸渍法制备了石墨烯/硫酸铅复合材料,使得硫酸铅可以直接用作铅酸电池负极材料。该复合材料分别以100 mA·g^-1、200 mA·g^-1和300 mA·g^-1电流密度放电时,平均放电比容量分别可达到110、94和69 mAh·g^-1,而硫酸铅仅为49、5和0.5 mAh·g^-1,显示出复合材料在高倍率充放电下更好的比容量和再接受充电能力。循环伏安测试表明石墨烯的电容效应随扫描速率增大而增强,同时析氢也变得严重,使得复合材料在充放电过程中充电效率比纯硫酸铅低20%。在充放电过程中,石墨烯能够提高硫酸铅1倍以上的放电容量,并将充电电压提高0.1 V。XRD和SEM结果显示硫酸铅均匀分布在石墨烯片层上,没有出现团聚现象。     

石墨烯/硫酸铅复合材料的制备及其在铅酸电池中的电化学性能

利用简单的浸渍法制备了石墨烯/硫酸铅复合材料,使得硫酸铅可以直接用作铅酸电池负极材料。该复合材料分别以100 mA.g-1、200 mA.g-1和300 mA.g-1电流密度放电时,平均放电比容量分别可达到110、94和69 mAh.g-1,而硫酸铅仅为49、5和0.5 mAh.g-1,显示出复合材料在高倍率充放电下更好的比容量和再接受充电能力。循环伏安测试表明石墨烯的电容效应随扫描速率增大而增强,同时析氢也变得严重,使得复合材料在充放电过程中充电效率比纯硫酸铅低20%。在充放电过程中,石墨烯能够提高硫酸铅1倍以上的放电容量,并将充电电压提高0.1 V。XRD和SEM结果显示硫酸铅均匀分布在石墨烯片层上,没有出现团聚现象。     

轻质柔性聚酰亚胺纸基电磁屏蔽材料的制备与性能

基于聚酰亚胺纤维纸基导电骨架(PI-CP)的三维网络结构, 通过聚吡咯(PPy)的气相沉积及无钯化学镀工艺在PI-CP上进行镍基金属的层层组装, 制备了夹芯结构的镍/聚吡咯@聚酰亚胺纤维纸基电磁屏蔽材料 (Ni/PPy@PI-CP); 对其形貌、 结构、 导电性能、 力学性能及电磁屏蔽性能进行了表征; 并考察了温度、 弯曲牢度和折叠次数对Ni/PPy@PI-CP导电性能和电磁屏蔽性能的影响. 研究结果表明, Ni/PPy@PI-CP-3的电磁屏蔽性能可达到70 dB以上; Ni/PPy@PI-CP-3在弯曲变形下表现出优良的导电稳定性, 其电导率损失可以忽略不计, 经过200次的反复弯曲测试, 其电导率仍保持在92.4%以上. 此外, Ni/PPy@PI-CP还具有轻质及易于加工的特性, 并具有稳定的热性能, 于300 ℃下处理后电磁屏蔽性能仍保持在80％以上.     

屏蔽EMI的金属及炭素填充的高分子复合材料

屏蔽EMI材料是现代电子、电器工业不可缺少的材料之一,尤其是屏蔽EMI高分子材料已经成为绝大多数信息技术设备的壳体材料,它们在现代电子工业中有着举足轻重的地位.本文对屏蔽EMI的方法及高分子复合材料的特性和发展概况等作简要介绍.     

铅卤钙钛矿-聚合物复合材料的制备及应用

铅卤钙钛矿纳米晶具有优异的光电性能,在太阳能电池、光电探测和生物成像等领域展现出巨大的发展潜力.然而,铅卤钙钛矿纳米晶自身稳定性差的缺陷制约了其在实际生活中的应用.将铅卤钙钛矿纳米晶嵌入到聚合物中以制备钙钛矿-聚合物复合材料是近年来发展起来的一种有效增强钙钛矿稳定性的策略,特别是致密的聚合物基质赋予钙钛矿纳米晶优异的水...     

Radiation degradation of poly(methyl methacrylate) in the soft x-ray region

The molecular weight distribution change has been measured for the photoresist poly(methyl methacrylate) [PMMA] after in-vacuo exposure to monochromatic soft x-rays from the Canadian Synchrotron Radiation Facility [CSRF]. The experimental changes in the mo-lecular weight distribations derived from gel permeation chromatography [GPC], were compared to a simple Monte Carlo simulation model that assumes random main chain scission. Using this model a scission radiation chemical yield of G(S) = 1.28± 0.10 at room temperature was found to give the best fit at a photon energy of 621 eV. This value is similar to values reported previously in the literature using electron beam and γ-ray sources, but significantly larger than those reported for fast neutrons, α-particles, or energetically charged particles. It was found that in this soft x-ray energy regime, that degradation of PMMA involves primarily a random scission process of the main chain. The results of a least-squares fit of this soft x-ray G(S) data and all available literature values from other radiation sources, to the linear energy transfer [LET] dE/dx are discussed. © 1993 John Wiley & Sons, Inc.     

半导体纳米复合材料ZnS/PMMA制备及其光学性质的研究

采用预聚法和溶胀法制备了具备光学透明性和可加工性的半导体纳米复合材料ZnS/PMMA. 用透射电镜(TEM)观察了ZnS纳米粒子在聚合物基体中的形貌. 结果表明， 基体中ZnS为六方晶型. 比较了分别以含锌微凝胶(ZnP)和ZnCl2为Zn2+源时,ZnS在基体中的生长情况. 紫外吸收和荧光光谱表明,掺杂了ZnS后的PMMA基体在280 nm处出现了一个新的吸收峰和强的荧光峰.     

Simple and effective one‐pot synthesis of (meth)acrylic block copolymers through atom transfer radical polymerization

The synthesis of di‐ and triblock copolymers using atom transfer radical polymerization (ATRP) of n‐butyl acrylate (BA) and methyl methacrylate (MMA) is reported. In particular, synthetic procedures that allow for an easy and convenient synthesis of such block copolymers were developed by using CuBr and CuCl salts complexed with linear amines. Polymerizations were successfully conducted where the monomers were added to the reactor in a sequential manner. Poor cross‐propagation between poly(n‐butyl acrylate) (PBA) macroinitiators and MMA was minimized, and therefore control of molecular weights and distributions was realized, by using halogen exchange—a technique involving the addition of CuCl to the MMA during the chain extension of the PBA macroinitiator. High molecular weight (M_n ∼ 90,000) and low polydispersity (M_w /M_n < 1.35) ABA triblock copolymers were also prepared and their structure and properties in bulk have been preliminary characterized indicating the potential of ATRP for the production of all‐acrylic thermoplastic elastomers. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 2023–2031, 2000     

微波辅助合成石墨烯/氧化镍复合材料及其表征

本文通过微波辅助的方法,快速而有效地在热膨胀石墨烯(RG)的缺陷上原位合成氧化镍纳米颗粒,形成石墨烯/氧化镍复合材料(RG/NiO)。利用X-射线衍射(XRD),拉曼光谱(Raman),傅里叶变换红外(FTIR),扫描电镜(SEM),透射电镜(TEM),热重-差热(TGA-DSC)对所制备样品的结构、形貌和NiO含量在复合材料中的含量进行表征。结果表明,热膨胀石墨烯层数约7~8层,层间距约为0.35nm,缺陷多,在水热和微波处理后抗氧化性明显变差。复合材料中氧化镍颗粒平均粒径为25nm,均匀而密集地分散在石墨烯平面上,同时在复合材料中的含量为19.8%。     

微波辅助合成石墨烯/氧化镍复合材料及其表征

本文通过微波辅助的方法,快速而有效地在热膨胀石墨烯(RG)的缺陷上原位合成氧化镍纳米颗粒,形成石墨烯/氧化镍复合材料(RG/NiO)。利用X-射线衍射(XRD),拉曼光谱(Raman),傅里叶变换红外(FTIR),扫描电镜(SEM),透射电镜(TEM),热重-差热(TGA-DSC)对所制备样品的结构、形貌和NiO在复合材料中的含量进行表征。结果表明,热膨胀石墨烯层数约7~8层,层间距约为0.35 nm,缺陷多,在水热和微波处理后抗氧化性明显变差。复合材料中氧化镍颗粒平均粒径为25 nm,均匀而密集地分散在石墨烯平面上,同时在复合材料中的含量为19.8%。     

Pseudo Capacitive Studies of Polyaniline-Carbon Nanotube Composites as Electrode Material for Supercapacitor

This study describes the formation of composites of polyaniline (PANI)-Carbon Nanotube (CNT) using in situ chemical oxidative polymerization of the monomer aniline. The PANI-CNT composites were characterized by FTIR and UV-Visible spectroscopy and XRD method. The surface morphology of the composites was characterized by scanning electron microscopy (SEM). Pseudo-capacitive behavior of deposited PANI over the surface of CNT was investigated by means of cyclic voltammetry. The composite was mixed with activated carbon for making the electrode. The specific capacitance of the prepared electrode was tested by means of a half cell test. The PANI-CNT composite with 0.02 M aniline in initial polymerization solution had the thinnest layer and highest specific capacitance of 597.82 F/g in 1 M H₂SO_4.     

超级电容器用石墨烯/金属氧化物复合材料

超级电容器是一种具有高功率密度和长循环寿命的新型储能装置,碳材料、金属氧化物和导电聚合物是常见的三种超级电容器电极材料。在石墨烯/金属氧化物复合材料中,石墨烯和金属氧化物可以发挥各自的优点,结合石墨烯优异的循环稳定性能和金属氧化物的高容量特性,纳米复合材料的综合性能可以得到很大地提升。因此,石墨烯/金属氧化物复合物的研究是超级电容器领域的热点研究方向之一。本文以金属氧化物的种类、石墨烯的结构和复合物的制备方法为线索,综述了国内外应用于超级电容器方面的石墨烯/金属氧化物复合材料的研究进展,归纳总结出与石墨烯复合最优的金属氧化物类型和制备方法,并进一步对该类复合材料的发展趋势进行了展望。     

X-Ray,Gamma, and Neutron Radiation Tests on Epoxy-Ferrochromium Slag Composites by Experiments and Monte Carlo Simulations

Radiation shielding effects of ferrochromium slag loading hardened epoxy resin samples were investigated. Five different samples including different percentages of epoxy resin and ferrochromium slag were produced. X-ray, gamma ray, and neutron particle transmission experiments were performed for epoxy-ferrochromium slag composites. Also, FLUKA Monte Carlo simulations were made to obtain absorbed doses. As a result, radiation shielding performance increases with increasing ferrochromium slag additive in epoxy.     

一种提高有机硅导电橡胶复合材料导电和电磁屏蔽性能的方法

描述了一种利用多元复合导电网络提高有机硅橡胶复合材料导电和电磁屏蔽性能的思想。这种含有多元复合导电网络的复合材料是通过将镀银泡沫、导电填料和有机硅橡胶复合在一起而制备的。利用扫描电子显微镜观察了复合材料的微观结构,采用电阻测试仪、矢量网络分析仪、热失重分析仪分别研究了复合材料的导电性、电磁屏蔽性能及热稳定性,并探讨了补强剂SiO2对这些性能的影响。结果表明,2%碳纳米管/导电泡沫/硅橡胶多元复合体系相比于2%碳纳米管/硅橡胶单一复合体系电阻率降低了6个数量级,平均电磁屏蔽效能由12dB提高到52dB,增大了4倍。当导电填料换为炭黑后,2%炭黑/导电泡沫/硅橡胶多元复合体系相比于2%炭黑/硅橡胶单一复合体系电阻率降低了7个数量级,平均电磁屏蔽效能由10dB提高到50dB,增大了5倍。由于多元复合导电网络,材料的导电性能和电磁屏蔽性能大幅度提升。此外,补强剂的加入增大了复合材料的热稳定性,但降低了其导电和电磁屏蔽性能。     

Poly(methyl methacrylate)-induced Microstructure and Hydrolysis Behavior Changes of Poly(L-lactic acid)/Carbon Nanotubes Composites

Poly(L-lactic acid)(PLLA)-based composites exhibit wide applications in many fields.However,most of hydrophilic fillers usually accelerate the hydrolytic degradation of PLLA,which is unfavorable for the prolonging of the service life of the articles.In this work,a small quantity of poly(methyl methacrylate)(PMMA)(2 wt%-10 wt%)was incorporated into the PLLA/carbon nanotubes(CNTs)composites.The effects of PMMA content on the dispersion of CNTs as well as the microstructure and hydrolytic degradation behaviors of the composites were systematically investigated.The results showed that PMMA promoted the dispersion of CNTs in the composites.Amorphous PLLA was obtained in all the composites.Largely enhanced hydrolytic degradation resistance was achieved by incorporating PMMA,especially at relatively high PMMA content.Incorporating 10 wt%PMMA led to a dramatic decrease in the hydrolytic degradation rate from 0.19%/h of the PLLA/CNT composite sample to 0.059%/h of the PLLA/PMMA-10/CNT composite sample.The microstructure evolution of the composites was also detected,and the results showed that no crystallization occurred in the PLLA matrix.Further results based on the interfacial tension calculation showed that the enhanced hydrolytic degradation resistance of the PLLA matrix was mainly attributed to the relatively strong interfacial affinity between PMMA and CNTs,which prevented the occurrence of hydrolytic degradation at the interface between PLLA and CNTs.This work provides an alternative method for tailoring the hydrolytic degradation ability of the PLLA-based composites.     

原位微区同步辐射X射线荧光和近边吸收谱研究铅耐受细菌吸附-转化铅机理

为了从微观水平研究细菌生物吸附及转化铅机理,利用原位微区同步辐射X射线荧光(μ-SRXRF)及X射线吸收近边结构谱( XANES)研究云南兰坪铅锌矿区农田土壤样品中筛选的铅耐受性细菌吸附铅的分布特征及铅形态转化规律。土壤中具有铅耐受性的菌株主要为Arthrobacter sp.属(节杆菌属),采用μ-SRXRF对其吸附铅的含量进行快速简单直接分析,部分细菌吸附铅的含量高达5925μg/g,富集系数达14.8。XANES结果表明,细菌吸附 Pb 后存在形态为 PbS、(C17 H35 COO)2Pb 和 Pb5(PO4)3Cl 分别占58.0％,22.2％和19.8％,与培养基本身以有机态为主的Pb形态有明显差异,表明培养基中铅被细菌吸附后有向硫化物转化的趋势,这为研究重金属生物有效性的影响因素提供了实验参考。     

Thermal crosslinking of poly(methyl methacrylate) by reaction of methyl ester and quaternary ammonium salt and application to (meth)acrylate-based TPEs

Copolymers of N-vinylbenzyl N-methyl pyrrolidinium chloride (VBMPC) and methyl methacrylate, PVBMPC-co-poly(methyl methacrylate) (PMMA), were synthesized by free-radical copolymerization and proved to be prone to crosslinking as a result of the reaction of methyl ester groups with benzyl methyl pyrrolidinium chloride (BMPC) moieties at temperatures higher than 110 °C. When the VBMPC content was lower than 20 wt %, these copolymers were miscible with homo-PMMA. Blends of homo-PMMA and PVBMPC-co-PMMA fully could be cured above 150 °C, when the molecular weight of PMMA exceeded 10,000 and the VBMPC content of the copolymer was higher than 5 wt %. This reaction was carried out to crosslink selectively the PMMA microdomains of PMMA-b-poly(isooctyl acrylate) (PIOA)-b-PMMA (MIM) triblock copolymers to explain the mechanism for the mechanical failure of fully (meth)acrylic thermoplastic elastomers. Comparison of the ultimate tensile properties of MIM block copolymers, when the dispersed PMMA phases and PIOA matrix were crosslinked, led to the conclusion that the ductile failure of the hard PMMA microdomains rather than the elastic failure of the PIOA matrix was the reason for the mechanical failure of MIM triblocks. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 4402–4411, 1999     

Synthesis, Characterization and Application of Benzyl-substituted Cyclopentadienyl lanthanide Complexes as Catalyst Precursors for the Syndiotactic Polymerization of Methyl Methacrylate

Benzyl-substituted cyclopentadienyl lanthanide complexes were synthesized and characterized by elemental analysis, MS and IR spectroscopy. The analytical data point out the formation of monomeric, unsolvated complexes.In conjunction with AI(Et)3 as co-catalyst, the title complexes are efficient catalysts for the syndiotactic polymerization of methyl methacrylate. For the complex (C6HsCH2C5H4)2YCl, under the optimum polymerization conditions(60℃,n(MMA):n(catalyst):n(co-catalyst)=1000:1:10),a predominantly syndiotactic (rr=66%) polymerof high molecular weight (Mη=105000) was obtained.     

胶体模板法制备有序大孔TiO2材料

以单分散的聚甲基丙烯酸甲酯(PMMA)微球为胶体模板, 采用钛酸丁酯、水、乙醇、盐酸等配成的混合溶胶填充在微球间间隙, 经水解形成凝胶, 然后通过程序升温焙烧去掉单分散的PMMA微球, 可得有序TiO₂大孔材料. 实验结果表明, 溶胶的配比为V(钛酸丁酯)∶V(水)∶V(乙醇)∶V(盐酸)＝5∶2∶3∶1, 在空气中凝胶20 h. 去掉单分散的PMMA微球的程序升温控制的条件为1 ℃/min的升温速率升到250 ℃恒定3 h, 再以2 ℃/min的升温速率升到450 ℃恒定8 h, 最后以10 ℃/min的降温速率降到室温.     

Curing and Physical Properties of Natural Rubber/Wood Flour Composites

Natural rubber based composites were prepared by incorporating Wood flour of two different particle size ranges (250–300 µm) and (300–425 µm) and concentrations (15 and 30 phr) into the matrix, using a Banbury® internal mixer according to a base formulation. Curing characteristics of the samples were studied. Influence of particle size and loading of filler on the properties of the composites was analyzed. Results obtained show that the addition of wood flour to natural rubber increased scorch time and curing time and caused improvement in modulus at 300% strain and in tear properties. However, it decreased tensile strength and elongation at break. The particle size range of 300–425 µm was found to offer the best overall balance of mechanical and dynamic properties (tan δ and viscous torque). Swelling behavior of the composites in toluene was also analyzed in order to determine the rubber volume fraction and crosslinking density. Composites with the bigger particle size wood flour were found to have greater crosslinking density than the ones with smaller particle size, fact that could possibly indicate a better rubber-filler interaction in the former. Major percentage of filler increased slightly this interaction. Water absorption behavior of the composites with wood flour reached a maximum of 12% w/w when 30 phr of filler were incorporated; nonetheless, particle size did not affect this property. The ageing study in presence of air at 70 °C revealed that natural rubber composites with wood flour maintained the same classification cell with temperature as the pure rubber. A compound with 30 phr of carbon black was prepared for comparative purposes. Results obtained were as expected. Scorch time decreased and higher values of modulus at 300% strain and tensile strength were achieved, due to strongest interaction between filler and elastomer.