In situ self-organization of carbon black–polyaniline composites from nanospheres to nanorods: Synthesis, morphology, structure and electrical conductivity

Nanostructured composites of polyaniline (PANI) with carbon black (CB) were synthesized by an in situ self-organization process. The synthesis is based on the polymerization of aniline in a micellar solution of p-toluenesulfonic acid (TSA) with different weight percentages of CB using ammonium peroxydisulfate (APS) as the oxidizing agent. Field emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FT-IR), UV–vis spectroscopy, and the four-probe meter were used to study the morphological, structural, thermal, and electrical properties of CB–PANI nanocomposites. The results demonstrate that the morphology, thermal stability, and electrical conductivity of the nanocomposites were significantly influenced by the content of CB. SEM results reveal that there was a transition in morphology from composite nanospheres to one-dimensional (1D) composite long nanorods with an increase of CB content. XRD and UV–vis spectra results revealed that there was an increase in the crystallinity and a shift of quinoid transition bands towards lower wavelengths as the amount of CB in the composite increased. The mechanism for the formation of nanostructured composites was explained on the basis of the self-organization of micelles. CB–PANI nanocomposites with a maximum electrical conductivity of 1.38 S/cm were obtained; this is at least three orders of magnitude higher than that of pristine PANI.     

Electrochemical characteristics of hydrothermally deposited nickel hydroxide on multi-walled carbon nanotube for supercapacitor electrode

Supercapacitor performance of nickel hydroxide powder electrode with different carbon conductor and nickel hydroxide/multi-walled carbon nanotube composite electrode had been studied by cyclic voltammetic method in 6 M KOH solution. Active carbon, Superp, Ketjen Black and multi-walled carbon nanotube were used as carbon conductor in nickel hydroxide powder electrode. It showed that multi-walled carbon nanotube conductor can bring good performance for nickel hydroxide powder supercapacitor electrode. Moreover, nickel hydroxide/multi-walled carbon nanotube composite was fabricated by hydrothermal method, using as supercapacitor electrode. Our findings show that 10 wt% nickel hydroxide loading on multi-walled carbon nanotube has good power performance. The capacitances for 10 wt% nickel hydroxide loading amount at high scan rate 100 and 500 mV/s were 221 and 118 F/g, respectively. Nickel hydroxide evenly loaded onto multi-walled carbon nanotube composite electrode has good conductivity and can contribute more capacitance.     

Effect of aluminum nitride-scandia content on the microstructural and mechanical properties of sintered silicon carbide ceramics

Two different SiC ceramics, one with 10 vol.% AlN-Sc₂O₃ in a 2:3 molar ratio, and the other with 20 vol.% of the same additives with the same ratio, were fabricated by hot-pressing at 1900 °C for 1 h and subsequent annealing at 2000 °C for 6 h in nitrogen. The grain boundary structures of both materials were observed by using high-resolution transmission electron microscopy. The results showed that both materials had clean boundaries without any amorphous films. Although both samples exhibited the same boundary structure, the sample with the higher AlN-Sc₂O₃ content contained more junction phases. The SiC ceramic with 10 vol.% AlN-Sc₂O₃ maintained its room-temperature strength up to 1400°C, whereas the SiC ceramic with 20 vol.% AlN-Sc₂O₃ showed a gradual decrease in strength at above 900 °C. The present results suggest that the high-temperature strength is dependent on the amount of junction phase, as well as the characteristics of the intergranular phase.     

Efficient and color stable phosphorescent white organic light-emitting devices based on an ultra wide band-gap host

We report high efficiency phosphorescent white organic light-emitting devices (WOLEDs) employing single emissive layer (EML) based on an ultra wide band-gap host. Effective exciton/charge confinement and balanced recombination within EML was achieved by employing adequate interlayer and stepwise hole-transporting layer (step HTL) system. Moreover, this step HTL system lower driving voltage of WOLEDs, therefore power efficiency was enhanced over 40%. These WOLEDs showed external quantum, and power efficiencies of 17.6%, and 37.5 lm/W at 100 cd/m² without outcoupling enhancements. We also found that these WOLEDs exhibited little change of color coordinate from 100 to 10,000 cd/m².     

Thermistor behavior of PEDOT:PSS thin film

The temperature-dependent resistance changing characteristics (thermistor behaviors) of a poly(3,4-ethylenedioxythophene):poly(4-styrenesulfonate) (PEDOT:PSS) thin film are investigated in the 30–100 °C range using Greek-cross and bar patterns. The PEDOT:PSS film was spin-coated onto a Si wafer passivated with a SiO₂ layer, and a conventional dry etching technique was used to pattern the PEDOT:PSS film in conjunction with a nitride etch mask layer. Cr/Au was used for the electrode material. It was found that the characteristic temperature (T₀) and resistivity of the PEDOT:PSS film have an inversely proportional relationship with the number of coatings and the number of interfaces between multiply coated PEDOT:PSS layers. It was also found that as the number of coatings and the number of the interfaces increase, lower temperature-dependent resistance changes are observed. The temperature coefficient of resistance (TCR) value of 60 nm thick PEDOT:PSS film was slightly larger than or comparable to that of a conventional metal (Au or Pt) thermistor. The possibility of utilizing the PEDOT:PSS thin film in thermistor applications is discussed.     

汽车尾气催化转化器的研究进展

如今,随着人们生活水平的不断提高,城市里汽车的数量正在以惊人的速度增长,但随之而来也有一些不容忽视的环境问题。但是由于发动机内部燃料的不完全燃烧,有许多燃烧不充分的产物如CO,HC,NOX等颗粒物,这些污染物对空气质量和人类健康都有非常不利的影响。文章给出了目前常用汽车尾气净化催化的机理,同时也讨论了汽车尾气净化催化剂及其载体的研究进展,催化转化器类型及其局限性,展望了汽车尾气净化催化剂的发展方向。     

一段炉转化管热带现象原因分析及处理

针对转化管出现的热带(超温)现象,结合一段炉的运行数据,从转化管改薄壁管、催化剂活性降低、催化剂结炭等方面进行分析与探讨,并采取一系列的操作优化及烧炭处理,避免了装置的停车,保证了系统的长周期稳定运行。     

CR/BIIR并用胶的性能研究

主要研究了氯丁橡胶(CR)/溴化丁基橡胶(BIIR)不同配比及不同增塑体系对并用胶性能的影响。结果表明,CR/BIIR并用胶在并用质量比为80/20,增塑体系选用固体古马隆树脂,且用量为10份时,并用胶的综合物理性能最好。采用氧化锌和硫黄共硫化体系,通过测量并用胶溶胀指数,并用胶的共硫化性较好,且CR/BIIR并用胶共混改性的相容性好。     

VMA1000胶料流动性分析仪在橡胶加工中的应用

针对目前橡胶行业普遍运用门尼黏度表征胶料加工流动性的现状,阐述了门尼黏度与流动性的不同以及产生流动性差异的原因。重点运用新型VMA1000胶料流动性分析仪,对实际胶料生产进行检测与质量控制,分析了影响胶料加工流动性的因素和流动性对橡胶加工的重要意义。     

Effect of thermal history during drying and curing process on the chain orientation of rod-shaped polyimide

Chain orientation in polyimide (PI) film is influenced by the thermal history during drying and curing process. The amount of residual solvent and the degree of imidization, among other factors, play a major role in determining the chain orientation during the process. In the present study, poly(amic acid), the precursor of PI, coated on the glass substrate was imidized to PI through different drying and curing protocols. On the way of complete imidization, the residual solvent concentration and the degree of imidization were characterized using confocal Raman spectroscopy. The poly(amic acid) began to imidize quickly while retaining more solvent in the film as the initial drying temperature increased. The degree of in-plane chain orientation in fully imidized PI film made by different process protocols was compared using polarized Raman spectroscopy. The fully imidized PI showed the lowest degree of in-plane chain orientation when it was processed by the protocol with the highest drying temperature. The difference in the degree of in-plane chain orientation among different PI films significantly influenced the in-plane thermal expansion coefficient, while no significant change in crystallinity or glass transition temperature was observed.