溶聚丁苯橡胶的序列结构及玻璃化温度与力学性能关系的研究

采用DSC和~(13)C-NMR等方法,将玻璃化温度(T_g)和溶聚丁苯橡胶(S-SBR)的序列结构关联起来,并以此为判据,将具有不同序列结构的S-SBR分为无规,短嵌段和长嵌段三种类型。T_g和序列分布对S-SBR性能的影响基本相似,硬度、拉伸强度、300％定伸应力和永久变形基本恒定,分别为72±2度、22±1.5MPa,11.0—13.0MPa和<12％;伸长率λ=-5627-15.8×T_g,弹性E=27.9-0.197T_g;分别求得无规型和短嵌段型S-SBR的λ、E与序列分布的线性关联式。     

精制水泥制品的工程性质和潜在应用

“精制水泥制品”指一类用较高技术制成的超高强水泥基材料。本文介绍了精制水泥制品的工程性质,以及在声学、低温学、装甲、电磁幅射屏蔽、电器和高放废物固化处理方面的潜在应用。     

Synthesis of porous carbon and silica spheres using PEO-PF polymer blends

In this paper, we performed a physical mixture of PEO and PF polymers (i.e. a polymer blend) as an organic template for synthesizing PF-PEO-silica homogeneous composites in a dilute silicate solution at pH = 4.0–5.0. The PF-PEO-silica composites exhibit spherical morphology, in micrometer dimension, and the sphere size is dependent on the pH value of the solution. After undergoing calcination to remove the organic part of the PF-PEO-silica composites with and without the hydrothermal treatment, porous silica spheres of different pore sizes were obtained. Due to the existence of the carbonizing PF polymer in the PF-PEO-silica composite, porous carbon spheres can be conveniently obtained from pyrolysis of the PF-PEO-silica composites under a N₂ atmosphere and HF-etching procedures. TEM images demonstrate that the mesostructures of the mesoporous silica and porous carbons are disordered.     

高分子壳聚糖衍生物改性膨润土制备新型吸附剂

用一种阳离子型壳聚糖衍生物改性膨润土,制备一种新型有机膨润土吸附材料,考察了制备条件对吸附剂吸附性能的影响。通过正交实验获得影响阳离子型壳聚糖衍生物在膨润土上负载的主要因素,并进行了单因素实验,考察主要因素对吸附性能的影响。实验结果表明,阳离子型壳聚糖衍生物的浓度、负载反应温度以及膨润土的活化温度是影响吸附剂吸附性能的主要因素。在以苯酚为目标吸附物时,当阳离子型壳聚糖衍生物的浓度为30g／L左右、膨润土的活化温度为240℃、负载反应温度为75℃时所制备的吸附剂的吸附性能最好,吸附剂的饱和吸附量可达到10．25mg／g（苯酚起始浓度为60ppm）,是未改性土的数十倍,可应用于低浓度含酚类废水的处理。     

太湖流域不同种浮萍淀粉积累的研究

对在太湖采集的15株浮萍进行分子鉴定,从中筛选出3株高淀粉含量浮萍作为供试材料,对其生长培养基进行优化,并研究饥饿条件对其生长和淀粉积累的影响。结果表明:采集到的浮萍分布于5个种,分别为Lemna aequinoctialis,Lemna minor,Lemna turionfera,Spirodela polyrhiza,Landoltia punctata;与SH培养基相比,改良的培养基SH-1和SH-2均能显著促进浮萍的生长;在饥饿试验中,筛选的3种浮萍S.polyrhizza,L.aequinoctialis和L.punctata每周的生长速率(以鲜重计)分别为18.64,20.77和16.52g/m2,饥饿培养33 d后,淀粉含量分别达到20.6%,21.98%和24.30%,较饥饿前分别增加了73.4%,75.4%和137.5%。相较于S.polyrhiza和L.aequinoctialis,L.punctata在淀粉积累方面表现出一定的优势。     

基于CLSSVM的风电机组齿轮箱故障诊断

针对风电机组齿轮箱传统故障诊断方法以全局误诊断率最小化为目标,忽略了误分类型之间的差别的问题,提出基于代价敏感最小二乘支持向量机(Cost-sensitive Least Squares Support Vector Machine,CLSSVM)的风电机组齿轮箱故障诊断方法。该方法在最小二乘支持向量机原始最优化问题中二次损失函数中嵌入不同样本的误分类代价,建立以误分类代价最小化为目标的CLSSVM故障诊断模型,并同最小二乘支持向量机和代价敏感支持向量机比较。实验结果表明,该方法能提高误分类代价高的故障类样本的诊断正确率,具有代价敏感性,其训练速度也足以满足风电机组齿轮箱故障诊断实时性的需求。     

Effects of hydrogen direct injection on engine stability and optimization of control parameters for a combined injection engine

As engine stability is a crucial issue for engine performance and toxic emissions, an experimental research has been conducted to analyze the effects of hydrogen direct injection on engine stability. The experiments have been divided into two parts. The first set is aimed to analyze different parameter characteristics with and without hydrogen direct injection, and the second set tries to find optimal control regions. Excess air ratios, spark timings, engine speeds and engine loads are chosen as primary parameters in the study. The results show hydrogen addition can increase brake thermal efficiency by a range from 6% to 13%, enhancing the lean burn performance. Combustion duration has been shortened to about 80% by adding 10% hydrogen mixture into gasoline. Besides, Hydrogen addition makes the mixture further insensitive to ignition timings, and narrows the optimal regions with higher excess air ratios. Under medium engine speeds, the highest CoV_IMEP locates in the low load region for pure gasoline, while this maximum value appears in the medium load region for 10% hydrogen mixture. In addition, the specific value of CoV_IMEP with 10% hydrogen is rather small compared to pure gasoline. Thus, hydrogen direct injection can significantly improve engine stability and reduce controlling difficulties.     

Pt and Ru dispersed on LiCoO2 for hydrogen generation from sodium borohydride solutions

Nano-sized platinum and ruthenium dispersed on the surface LiCoO₂ as catalysts for borohydride hydrolysis are prepared by microwave-assisted polyol process. The catalysts are characterized by transmission electron microscopy (TEM), X-ray diffractometry (XRD) and X-ray photoelectron spectroscopy (XPS). Very uniform Pt and Ru nanoparticles with sizes of <10 nm are dispersed on the surface of LiCoO₂. XRD patterns show that the Pt/LiCoO₂ and Ru/LiCoO₂ catalysts only display the characteristic diffraction peaks of a LiCoO₂ crystal structure. Results obtained from XPS analysis reveal that the Pt/LiCoO₂ and Ru/LiCoO₂ catalysts contain mostly Pt(0) and Ru(0), with traces of Pt(IV) and Ru(IV), respectively. The hydrogen generation rates using low noble metal loading catalysts, 1 wt.% Pt/LiCoO₂ and 1 wt.% Ru/LiCoO₂, are very high. The hydrogen generation rate using Ru/LiCoO₂ as a catalyst is slightly higher compared with that of Pt/LiCoO₂.     

大、小飞扬草中锌铁锰微量元素的测定

目的:测定大、小飞扬草中Zn、Fe、Mn三种微量元素的含量。方法:硝酸和高氯酸(4+1)分解样品,火焰原子吸收光谱法(FAAS)测定。结果:大、小飞扬草中三种微量元素存在差异,其中大飞扬草中元素含量大小为:Fe>Mn>Zn,小飞扬草中上述元素含量为:Fe>Zn>Mn。回收率在97.0%~106.0%之间,RSD<2.1%。结论:大、小飞扬草中三种微量元素含量的差异测定可为进一步研究其药效与有关微量元素关系提供一定参考。     

Processing‐dependent high impact polystyrene/styrene‐butadiene‐styrene tri‐block copolymer/carbon black antistatic composites

The electrical resistivity and morphology of high impact polystyrene (HIPS)/styrene‐butadiene‐styrene triblock copolymer (SBS)/carbon black (CB) blends were studied. Their antistatic sheets were prepared by both compression‐molding and extrusion calendaring process, with their surface morphology observed using scanning electron microscopy (SEM). The SEM images reveal better dispersion of CB achieved in extrusion‐calendering, resulting in low percolation threshold values in HIPS composites. Higher compression ratio and higher drawing speed (corresponding lower sheet thickness) are beneficial to get better CB dispersion, leading to decreased conductivity for the antistatic sheets. SEM images indicate that strong shear forces in extrusion tend to break the conductive network of CB, resulting in increased surface resistivity. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011