Effect of water content on the size and membrane thickness of polystyrene-block-poly(ethylene oxide) vesicles

The asymmetric amphiphilic block copolymer polystyrene962-block-poly(ethylene oxide)227(PS962-b-PEO227) canforms micelles with N, N-dimethylformamide(DMF) as co-solvent and water as selected solvent, and when the water content of the mixed solvent is higher than 4.5 wt%, the vesicle will be dominated. This work finds that once vesicles are formed in the DMF-water mixed solvent, the vesicle size and membrane thickness can be tuned by further increasing water content. As the water fraction elevated from 4.8 wt% to 13.0 wt%, the vesicle size dercreases from 246 nm to 150 nm, while the membrane thickness increases from 28 nm to 42 nm. In addition, the block copolymer packing and the free energy are analyzed as the vesicle size becomes small and the membrane becomes thick.     

Effects of ultra-high temperature treatment on the microstructure of carbon fibers

The microcrystalline structure and microvoid structure in carbon fibers during graphitization process(2300-2700 °C) were characterized employing laser micro-Raman scattering(Raman), X-ray diffraction(XRD), small angle X-ray scattering(SAXS), and high-resolution transmission electron microscopy(HR-TEM). The crystalline sizes(L_a, L_c) increased and interlayer spacing(d_(002)) decreased with increasing heat treatment temperature(HTT). The microvoids in the fibers grew up and contacted to the neighbors with the development of microcrystalline. In addition, the preferred orientation of graphite crystallite along fiber axis decreased and microvoids increased. The results are crucial for analyzing the evolution of microstructure of carbon fibers in the process of heat treatment and important for the preparation of high strength and high modulus carbon fibers.     

A developed full-field fem analysis combined with ESPI for the investigation of defect evolution in polymer films

A full-field finite element method (FEM) analysis combined with electronic speckle pattern interferometry (ESPI) measurement was developed to investigate defect evolution in polymer films. Different from the previous reports, which only compare the ESPI experimental and FEM simulated results at several points or lines, herein the full-field FEM results were exported, subtracted with a continuous distribution. By choosing proper parameters and number of substeps, the simulated and experimental results showed excellent correspondence. Furthermore, the displacement fields vertical to the tensional direction were also presented, and the strain field was preliminarily evaluated. The current method of combination of ESPI and FEM allows for capturing the experimental fringe maps to validate and optimize FEM results simulated, and would give a higher security to structural and mechanical analysis of polymeric materials.     

可控变色织物制备及颜色控制研究

基于聚苯胺电致变色高聚物、采用反射型电致变色器件结构模型,以柔性导电织物作为电极,构建了可控变色织物,可在-1.0～+1.0 V低电压范围内实现颜色变化显著的黄色和绿色的可逆响应.系统研究了变色织物在不同电压、不同弛豫时间及不同颜色工作电极下的L*a*b*,ΔE*值及反射率曲线,且讨论了透射型电致变色器件和电致变色织物的区别.随着正电压的增加,变色织物对应的a*b*依次减小,蓝绿色加深;随着负电压的增加,变色织物对应的a*b*依次增加,变色织物黄色加深.撤去电压后变色织物发生放电弛豫,慢慢回复到未加电压时的本征态.工作电极底色对电致变色织物也有显著的影响.变色织物的断电放电弛豫时间低于透射型电致变色器件.     

地热水驱动双级有机闪蒸循环热性能研究

以R601、R601a、R123、R227ea、R245fa、R600、R600a、R236ea为循环工质,以150℃地热水作为热源温度,建立了双级OFC系统模型,对系统的热性能进行了研究,同时揭示了不同工质的低压级最优闪蒸压力.结果 表明,当循环工质为R601,高压级闪蒸压力为630.53 kPa时,双级OFC的净输...     

超高分子量聚乙烯纤维表面改性的研究进展

超高分子量聚乙烯(UHMWPE)纤维具有诸多优异性能,因此被广泛应用于纤维增强复合材料(FRP)。但是由于UHMWPE纤维表面光滑且无极性基团,与树脂基体粘接性差,可通过纤维表面改性有效提高FRP的界面强度,进而提升材料性能。本文总结了近几年基于化学处理、等离子体处理、电晕放电和辐射引发表面接枝等方法对UHMWPE纤维表面改性的研究进展,并对改性方法的发展进行了展望。     

STUDY ON A HYDROPHOBIC-HYDROPHILIC GRADIENT ROD

INTRODUCTIONGradient materials constitute a special case of various materials. The concentration of one of the components ofthe material, being chemically and/or physically different from other components, is allowed to change as afunction of its position in the sample, producing a predetermined gradient profile. The gradient material can be inany shape — i.e., linear, sigmoid, parabolic, flat or rod. Generally, this kind of material should have gradientsalong one direction in their stru…     

聚苯胺基反射型柔性电致变色器件的制备与工艺研究

采用化学法合成聚苯胺(PANI),在柔性不锈钢丝网上进行涂覆,成功制备了反射型柔性变色器件.测试并获取了不同电位下(即不同的掺杂态)的紫外-可见光全反射光谱,比较确定了该变色器件合适的使用电压为+0.7V和-0.6V.并在选定的使用电压下对变色器件进行测试,讨论了工作电极上PANI用量、电解质层用量和离子储存层用量对变...