Synthesis of polypropylene‐graft‐maleic anhydride compatibilizer and evaluation of nylon 6/polypropylene blend properties

Polymer blends based on polyolefins are of a great interest owing to their broad spectrum of properties and practical applications. However, because of poor compatibilities of components, most of these systems generally exhibit high interfacial tension, a low degree of dispersion and poor mechanical properties. It is generally accepted that polypropylene (PP) and nylon 6 (N6) are not compatible and that their blending results in poor materials. The compatibility can be improved by the addition of a compatibilizer, and in this study PP was functionalized by maleic anhydride (MAH) in the presence of an optimized amount of dicumyl peroxide (DCP). The reaction was carried out in the molten state using an internal mixer. Then, once the compatibilizer polypropylene‐graft‐maleic anhydride (PP‐g‐MAH) was prepared, it was added at various concentrations (2.5–10 wt%) to 30/70 glass fibre reinforced N6 (GFRN6) PP, and the mechanical properties were evaluated. It was found that the incorporation of the compatibilizer enhanced the tensile properties (tensile strength and modulus) as well as the Izod impact properties of the notched samples. This was attributed to better interfacial adhesion as evidenced by scanning electron microscopy (SEM). The optimum in these properties was achieved at a critical PP‐g‐MAH concentration. Copyright © 2005 Society of Chemical Industry     

The Influence of Medium on Low-Voltage Circuit Breaker Arcs

This paper mainly focuses on the influence of three kinds of media： air, air-10%PA （Nylon） and air-10% POM （polyoxymethylene） on low-voltage circuit breaker arcs. A threedimensional （3-D） model of arc motioa under the effect of external magnetic field is built based on magnetohydrodynamics （MHD） equations. By adopting the commercial computational fluid dynamics （CFD） package based on the control-volume method, the above MHD equations are solved. For the media of air-10%PA and air-10%POM, the distributions of stationary temperature and electrical potential and the transient motion processes are compared with those of air arc. The research shows that both air-10%PA and air -10% POM can cool the arc plasma and the former is more effective. Both of them can increase the stationary voltage as well. Moreover, the presence of the two mixtures can accelerate the arc motion toward the quenching area and ensures the arc quenched in time.     

Surface characterization of PET nonwoven fabric treated by He/O2 atmospheric pressure plasma

The surface of polyethyleneterephthalate (PET) nonwoven fabric was modified by He/O₂ atmospheric pressure plasma treatment, varying plasma exposure time. The plasma treated PET surfaces have been analyzed to investigate the chemical nature and morphology of surface by X‐ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM), respectively. The change of wettability was measured depending on plasma exposure time. XPS results indicated the presence of oxygen‐based functional groups on the PET nonwoven fabric surface after plasma treatment and oxygen content increased as exposure time increased. The mean roughness increased after 30 s exposure and further increase in exposure to 60 s led to decrease of the roughness and then again increase. The root mean square roughness followed the similar trend to mean roughness. The average difference in height, Rz, increased after plasma exposure for 30 s, while it slightly decreased after 60 s exposure. Despite of redeposition, the Rz of 90 s exposed sample increased more than two times compared with those of 30 and 60 s exposed. Wettability increased progressively up to 10 times after 90 s exposure compared with the untreated. It is attributed to the increases of hydrophilicity and surface roughness. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

DJG-1阳离子絮凝剂合成的影响因素

DJG-1阳离子絮凝剂的合成步骤为：玉米淀粉与丙烯酰胺在硝酸铈铵引发下接枝，得A；A与醇在酸催化下发生酯化反应得B；甲醛与二甲胺反应得N-羟甲基胺（C）；在C中加入酸使pH值为4左右。得酸性范围内的N-羟甲基胺（C′）。B与C′发生曼尼希反应得D（叔胺盐）；D发生烷基化反应E（季铵盐）；E与四苯硼钠反应生成白色沉淀。室内试验分析了DJG-1阳离子絮凝剂合成的影响因素。评价了DJG-1的水处理效果并与硫酸铝进行了对比。实验结果表明，DJG-1阳离子絮凝剂合成的影响因素包括引发剂的选用，活化时间，投料比，反应时间与温度及溶液pH值等。用DJG-1絮凝剂混凝处理钻井废水时，絮凝沉淀的速度比用硫酸铝处理时大得多，废水处理效率高，但DJG-1絮凝剂与硫酸铝复合使用经济效益更好，且硫酸铝用量为300mg/L时，DJG-1的最佳用量为3-4mg/L。     

Plasma properties of laser-ablated St target in air

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光柱显示技术探讨

本文叙述自动化仪表用光柱显示技术的工作原理及器件结构，重点论述直流等离子体光柱，发光二极管光柱，真空荧光及液晶光柱器件的结构和驱动电路，还展望光柱显示的发展趋势。     

Methacrylic acid–acrylamide-g-poly(ethyleneterephthalate) fibres for urea hydrolysis

This paper presents the results of urease immobilization onto methacrylic acid–acrylamide grafted poly(ethyleneterephthalate) fibres. The graft yield strongly affected the maximum activity of the immobilized enzyme up to a value of 70·2%. Higher grafting caused a decline in urease activity and led to the degradation of the fibres. The minor changes observed in K_m and V_max demonstrated that the conformational changes existed during immobilization were not extensive. However, 70·2% methacrylic acid–acrylamide-g-fibres containing urease were more stable towards acidic and alkaline pH, high temperature and storage conditions compared with free enzyme. Apart from the increase in stability to heat inactivation, the initial enzymatic activity of the urease–fibre system remained almost unchanged even after 40 repeated assays corresponding to 10 h of operation in 4 months, indicating the excellent durability of the system.     

PE－AA辐射接枝共聚合的反应历程研究

研究了聚乙烯（ＰＥ）与丙烯酸（ＡＡ）、甲基丙烯酸（ＭＡＡ）的接枝共聚反应，探讨了接枝反应过程及特征：单体首先在ＰＥ表面接枝，然后进入内部进行本体接枝。研究表明：表面接枝为动力学控制，本体接技系扩散控制，单体在膜内的扩散与单体极性及聚合物的结晶度等有关     

聚烯烃塑料改性的研究进展

聚乙烯、聚丙烯以优良的力学性能、热性能、加工性能等成为最主要的聚烯烃塑料品种,大量用于生产薄膜、管材和板材。通过改性可获得高刚性、高强度、高耐热、低成本的聚烯烃塑料。综述了近年来聚乙烯和聚丙烯在接枝、交联、填充、共混等方面的改性进展,并指出了研究方向和发展趋势。     

氯丁橡胶的溶液接枝反应研究

本文研究了引发剂过氧化苯甲酰的用量对ＣＲ接技ＭＭＡ－ＡＡ反应的单体转化率、接枝率及接枝胶的粘度、剥离强度等的影响，并用红外光谱和元素和元素分析对反应产物进行了表征．结果表明，体系中存在接枝、降解、交联三种反应，在不同的配方和工艺条件下，三种反应的反应程度不同．