Measurements of HO2 uptake coefficient on aqueous (NH4)2SO4 aerosol using aerosol flow tube with LIF system

The γ(HO₂) was elevated with increase of Cu(II) concentrations in aqueous (NH₄)₂SO₄ aerosol. The threshold of Cu(II) concentration was 10^-3 mol/L for the dramatic increase of γ(HO₂) to 0.1, suggesting sensitive γ(HO₂) value to concentration of transition metal ions in aerosol.     

Metallocene-mediated synthesis of chain-end functionalized polypropylene and application in PP/clay nanocomposites

This paper summarizes our research in the preparation of chain end functionalized isotactic polypropylene (PP) having a terminal functional group, such as Cl, OH, and NH₂. The chemistry involves metallocene-mediated propylene polymerization using rac-Me₂Si[2-Me-4-Ph(Ind)]₂ZrCl₂/MAO complex in the presence of styrene derivatives (St-f) and hydrogen, which serve as the chain transfer agents. The molecular weight of the resulting PP polymers with a terminal Cl, OH and NH₂ group (i.e., PP-t-Cl, PP-t-OH and PP-t-NH₂) are inversely proportional to the molar ratio of [St-f]/[propylene]. Despite the extremely low concentration of functional group, the high molecular weight chain end functionalized PP-t-OH and exhibit a distinctive advantage over other functional PP polymers containing side chain functional groups or long functional blocks. The terminal hydrophilic OH and cations, with good mobility and reactivity, effectively hydrogen bond and ion-exchange the cations (Li⁺, Na⁺, etc.) located between the clay interlayers, respectively. Such interactions anchor the PP chain to the clay surfaces. On the other hand, the remaining rest of the unperturbed end-tethered high molecular weight PP tail exfoliates the clay layers. This exfoliated structure is maintained even after further mixing of the PP-bearing platelets with pure neat PP polymers.     

掺铬铝酸钇红色颜料的合成、结构和性能表征

研究了高温固相合成制备掺铬铝酸钇红色颜料的方法，着重考察了灼烧温度（1000-1400℃）、灼烧时间（1-2h）、主要原料配比（Al／Y：1：0．5—1：1．5，Cr2O3％：0．3％-5％）等实验条件对产物结构和色泽的影响。XRD等方法对样品进行的相态分析表明，主相为铝酸钇石榴石相；运用反射光谱对红色颜料的色泽进行了反射峰位和相关强度的表征。当Y2O3：Al2O3摩尔比为1：1，掺杂3％的Cr2O3作显色剂，在少量矿化剂存在时，在1300℃下灼烧1 h，得到了色坐标为x=0．577，Y=0．401的红色陶瓷颜料。     

缩聚合成聚芳酯和聚酯－聚醚弹性体的微相复合物

通过原位直接缩聚反应，制备了刚性棒状聚对羟基苯甲酸酯（ＰＨＢ）和聚对苯二甲酸丁二醇酯－聚四亚甲基醚多嵌段共聚物（ＰＢＴ－ＰＴＭＧ）的微相复合物．复合物可溶于氯仿等溶剂，可以浇铸成膜．本文研究了ＰＨＢ含量和聚合过程中，基体聚合物溶液浓度对微相复合物形态以及力学性能影响．同共混法相比，原位缩聚法可得到分散更均匀，力学性能更优良的微相复合物．     

Heat transfer in polymer composites filled with inorganic hollow micro-spheres: A theoretical model

The heat transfer mechanisms in inorganic hollow micro-spheres filled polymer composites are analyzed in the present paper. This heat transfer includes mainly three mechanisms: (1) thermal conduction between solid and gas; (2) thermal radiation between the hollow micro-sphere surfaces; and (3) natural thermal convection of the gas in the micro-hollow spheres. A theoretical model of heat transfer in polymer/inorganic hollow micro-sphere composites is established based on the law of minimal thermal resistance and the equal law of the specific equivalent thermal conductivity, and a corresponding equation of effective thermal conductivity is derived. The effective thermal conductivity (k_eff) of hollow glass bead-filled polypropylene composites is estimated by using this equation, and is compared with the numerical simulations by means of a finite element method. The results show that the variation of the theoretical estimations of k_eff are similar to the numerical simulations at lower filler volume fraction (φ_f20%). Moreover, k_eff decreases linearly with increasing φ_f, and reduces somewhat with increase of filler size.     

石墨炉原子吸收法中热解涂层石墨管在无标准分析法测定环境样品中铬的应用

本文探讨了热解涂层石墨管测定铬的最佳实验条件,研究了各种酸和干扰物质的基体效应,提出用浓氨水为基体改进剂克服高氯酸的干扰。比较了各原子化温度时的理论和实验特征量。使热解涂层石墨管有可能用于无标准分析法测定各种环境样品中的铬。     

石墨炉原子吸收法测定钒的研究

本文比较了在标准石墨管,热解涂层和全热解石墨管中钒的吸收信号形状。用全热解石墨管和EDTA铵盐作基体改进剂,直接测定水系沉积物中痕量钒。方法的特征量为61pg/0.0044A。     

CuCrAl和CuCrZr低温液相合成甲醇催化剂的研究

 用络合共沉淀法制备了CuCrAl和CuCrZr复合氧化物液相合成甲醇催化剂，其比表面分别达到119和116m2／g．在5．0～5．5MPa和383K条件下，分别用间歇式和流动式反应釜考察了催化剂的活性和稳定性．结果表明：CuCrAl和CuCrZr的活性均明显高于CuCr；CuCrAl的活性略高于CuCrZr，但甲酸甲酯（MF）的选择性明显低于CuCrZr；两者在12h内未见活性明显下降．甲醇钠在反应过程中部分转化为甲酸钠和NaOH．CuCrAl和CuCrZr有较高的氢解活性可抑制甲醇钠与MF生成甲酸钠，从而有较低的甲酸钠浓度．但是，Al2O3和ZrO2的酸性有利于甲醇脱水，引起甲醇钠水解生成NaOH．溶剂对CuCr基催化剂的活性和选择性有明显影响．对反应机理进行了讨论．     

导电复合材料葡萄糖氧化酶传感器的研究

报导了用乙基纤维素和乙炔黑获得的导电复合材料构成的葡萄糖氧化酶生物传感器的制备方法.讨论了多种因素对该生物传感器响应电流的影响.测得此电极酶催化反应的活化能为40.3 kJ•mol－1. AFM实验表明，用环己烷洗去石蜡的导电复合材料 葡萄糖氧化酶生物传感器具有粒状结构，这有利于酶催化反应的进行.