NCT310型常温氧化锌脱硫剂的研究

介绍了NCT310型常温氧化锌脱硫剂实验室研究情况。结果表明，在常温（20～60℃）下，该脱硫剂对气体中的硫化氢有优越的脱除性能。在40℃、1000h-1、进口H2S～1．5g／m3条件下，可控制出口H2S＜7×10－4g／m3，穿透硫容（重量比）＞10％。     

Crystalline morphology and isothermal crystallization kinetics of poly(ethylene terephthalate)/clay nanocomposites

A poly(ethylene terephthalate) (PET)/montmorillonite clay nanocomposite was synthesized via in situ polymerization. Microscopic studies revealed that in an isothermal crystallization process, some crystallites in the nanocomposite initially were rod‐shaped and later exhibited three‐dimensional growth. The crystallites in the nanocomposite were irregularly shaped, rather than spherulitic, being interlocked together without clear boundaries, and they were much smaller than those of neat PET. With Avrami analysis, the isothermal crystallization kinetic parameters (the Avrami exponent and constant) were obtained. The rate constants for the nanocomposite demonstrated that clay could greatly increase the crystallization rate of PET. The results for the Avrami exponent were consistent with the observation of the rodlike crystallites in the PET/clay nanocomposite during the initial stage. Wide‐angle X‐ray scattering and Fourier transform infrared studies showed that, in comparison with neat PET, the crystal lattice parameters and crystallinity of the nanocomposite did not change significantly, whereas more defects may have been present in the crystalline regions of the nanocomposite because of the presence of the clay. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 1381–1388, 2004     

HDPE耐环境应力开裂性能的研究及改进

对HDPE的耐环境应力开裂性能进行了研究。试验表明:采用共混及化学改性的方法,HDPE的耐环境应力开裂性能有了很大提高,为解决HDPE树脂在制作管材时出现的短时间内应力开裂问题提供了依据。     

用六水氯化钙作为相变材料的换热器储热性能研究

研究了一种以传统的管壳式换热器作为结构基础、管内充填相变材料——六水氯化钙的新型相变材料换热器的储热性能。对这种新型相变材料换热器分别通入温度不同的冷热流体，利用温度测试系统对其进口、出口的温度进行了测试。实验结果表明，这种相变材料换热器结构能将温度较高的热流体的热能通过其管内充填的相变材料储存起来，必要时又可以将储存的热能释放给所需的流体中，从而使其既具有热量交换的功能又具有热量储存的功能。它主要适用于温室、暖房、工业生产中的低品位热能的回收和利用，还可以应用于热能供应与人们需求之间不一致的场合，如太阳能热利用、采暖和空调领域等。     

锌基重防腐双涂层防护技术在高速公路护栏上的应用

介绍了双涂层防护技术的进展以及锌基重防腐双涂层防护技术在高速公路护栏上的应用。     

Computer simulation of electrospinning. Part I. Effect of solvent in electrospinning

Electrospinning technique has been recognized as an efficient method to manufacture nano-fiber. At present, research focuses on the structure and morphology of the fibers, a few investigations have been reported the mechanism of electrospinning. In our experiment, appropriate polymer EVOH (ethylene/vinyl alcohol copolymer) and different solvents were chosen, the energy change in the process of molecule orientation was analyzed by computer simulation, and the morphologies of the fiber were indicated by scanning electron microscope (SEM). Results indicate that: in the process of molecule orientation, some barriers should be overcome; the height of the barrier is determined by the relaxation times (τ) of the molecule. The relaxation times vary in different solutions, when the relaxation time is short, the orientation of molecule is easy, so jet instability will be fierce, and fibers with small diameter are obtained.     

The preparation of coupled WO3/TiO2 photocatalyst by ball milling

The coupled photocatalyst WO₃/TiO₂ is prepared by ball milling by doping WO₃ into TiO₂ and using H₂O solution as disperser. The coupled photocatalyst WO₃/TiO₂ is characterized by UV–VIS diffuse reflection spectrum, X-ray photoelectron spectroscopy (XPS), X-ray powder diffraction (XRD) and Transmission electron microscopy (TEM). The results show that the optimum percentage of WO₃ doped is 3% and that the photocatalytic activity of the coupled WO₃/TiO₂ photocatalyst is much higher than that of TiO₂ and WO₃–TiO₂ with no ball milling. Compared with TiO₂, the photoexcited wavelength range of the WO₃/TiO₂ photocatalyst red-shifts about 50 nm, and the light absorption intensity is also improved. The crystal phase of TiO₂ is not changed and new crystal phases are not found during the process of ball milling. WO₃ and TiO₂ coupled highly, forming the WO₃/TiO₂ photocatalyst. The increased photocatalytic activity of the coupled photocatalyst may be attributed to the enhance charge separation efficiency and the extend wavelength range of photoexcitation.     

Synthesis of hydroxyapatite nanoparticles in ultrasonic precipitation

Nanocrystalline hydroxyapatite (HAp) was prepared by a precipitation method with aid of ultrasonic irradiation using Ca(NO₃)₂ and NH₄H₂PO₄ as source material and carbamide (NH₂CONH₂) as precipitator. The crystallization and morphology of the prepared nanoparticles were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The mechanism and kinetics of the nano-hydroxyapatite were considered in particular, and the influence of the temperature and time on the HAp formation rate was also investigated. The results show that the needle-like HAp crystalline was prepared by the ultrasonic precipitation process. The HAp content increases with the preparation temperature and time. The adding of carbamide is helpful for formation of HAp nanoparticles. An Arrhenius relationship was found between the HAp formation rate and the temperature, and an apparent activation energy of 59.9 kJ/mol was obtained by calculation.     

The influence of resin characteristics on the high speed melt spinning of isotactic polypropylene. II. On-line studies of diameter,birefringence, and temperature profiles

An investigation was carried out of the high speed melt spinning of three polypropylene resins with melt flow indices of 12, 35, and 300. On-line measurements were made of diameter, birefringence, and temperature as a function of distance from the spinneret for a range of spinning conditions for each polymer. A plateau (decrease of cooling rate) in the temperature profile was associated with the occurrence of crystallization in the spinline. The position of this plateau correlated with a rapid rise in the birefringence profile and a rapid decrease in the rate of drawdown in the diameter profile. The temperature and birefringence profiles were used to determine the temperature and position on the spinline at which the onset of crystallization occurred. It was found that the position and temperature of crystallization onset varied considerably with changes in take-up velocity, extrusion temperature, and resin melt index (weight average molecular weight). The crystallization onset occurred nearer the spinneret and at higher temperatures with (1) an increase of take-up velocity, (2) a decrease of extrusion temperature, or (3) a decrease of resin melt flow index. An analysis was carried out to estimate the rate of stress development with distance along the spinline; the results were also used to estimate the stress at the onset of crystallization for each spinning condition. It was concluded that the observed behavior could be attributed to the role of spinline stress in producing molecular orientation and consequent increase of crystallization rate.     

基于Retinex和BM3D的图像增强

为克服传统Retinex算法没有解决的噪声问题,提出了一种基于Retinex和BM3D的图像增强算法。该方法将BM3D去噪环节加入到传统Retinex算法中。首先,计算出图像各像素之间的相对明暗关系,进而对待处理图像中的每个像素点灰度值进行校正;然后,通过在相邻图像块中搜索相似块,组成一个三维矩阵,并在三维空间进行滤波处理,得到块预估计值;最后,对图像中每个点进行加权得到最终的处理结果。实验结果表明,该算法既能显示阴影、光照区域中的细节,又能有效消除图像中含有的噪声,克服了传统Retinex图像增强算法的不足。