Synthesis and characterization of copoly(arylene sulfide)s

Copolymerizations of p-dichlorobenzene (DCB)/4-bromophenyl ether (BPE), DCB/4,4′-dibromobiphenyl (DBB), and DBB/BPE pairs with sodium sulfide under high temperature (270–290°C) utilizing N-methyl-2-pyrrolidinone (NMP) as solvent were carried out to give C(DCB/BPE), C(DCB/DBB), and C(DBB/BPE) copolymers, respectively. The reactivity of dihaloaromatic monomers toward thiolate anion in the polycondensation reaction followed the order DBB > DCB > BPE. The reactivity gap between DBB and DCB toward thiolate anion seemed to be smaller than that between BPE and DCB, resulting in both high yield and high molecular weight in the C(DCB/DBB) copolymers compared to C(DCB/BPE) copolymers. The copolymerization of DBB/BPE pair with sodium sulfide, which has larger reactivity gap than the DCB/DBB or DCB/BPE pair, gave mixtures of PBS and PPSE homopolymers especially in the range of 50–80 mol % BPE in the feed. The C(DCB/DBB) and C(DCB/BPE) copolymers, however, exhibited random copolymer character in all comonomer ratios in the feed as evidenced by copolymer composition and DSC data. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 2311–2317, 1999     

Adsorption of the Ternary Liquid Mixture Ethanol/n-Octane/n-Hexadecane onto Activated Carbon: I. The Adsorption Excess of the Ternary Mixture and of Its Binary Combinations

The adsorption isotherms of the binary mixtures of ethanol/n-Octane, ethanol/n-hexadecane and n-octane/n-hexadecane onto the activated carbon TA 95 were measured at 278 K, 288 K, 298 K and 308 K and described with mathematical functions. About 300 experimental values of the adsorption excess of the ternary mixture ethanol/n-octane/n-hexadecane onto activated carbon TA 95 at 298 K were measured by gas chromatography inside the ternary triangle. The ternary miscibility gap was determined at three temperatures. A good representation of the ternary data and the calculated activity coefficients (using the UNIFAC model) in three-dimensional space was possible with the help of transformation of coordinates. It was possible, too, by utilization of the conception of the quasi two-component representation of the mole fractions with and without miscibility gap. Several influencing factors on ternary adsorption isotherms were discussed for the system ethanol/n-octane/n-hexadecane/TA 95.     

A Theoretical Approach to Temperature Modulated Power Compensation DSC

The steady state of temperature modulated power compensation DSC has been theoretically investigated for measurements of complex heat capacity, taking accounts of heat capacities of heat paths, heat loss to the environment, and mutual heat exchange between the sample and the reference material. Thermal contact between the sample cell and the cell holder is also taken into accounts. Rigorous and general solutions are obtained. From these solutions application of the technique to heat capacity measurements is discussed. This revised version was published online in August 2006 with corrections to the Cover Date.     

A Series Piezoelectric Quartz Crystal Microbial Sensing Technique Used for Biochemical Oxygen Demand Assay in Environmental Monitoring

A new method for biochemical oxygen demand (BOD) determination, which combines the series piezoelectric quartz crystal (SPQC) technique with the growth of a microorganism is presented in this paper. This method needs no immobilization of bacteria and is simple and convenient. When a calibration technique was used for BOD analysis, the detection time was 2.5 h at 37°C. There was a good linear relationship between the frequency shift and BOD value in the range 2.2–11 mg/L and the regression equation was ΔF = 64.10 + 11.23[BOD]. The proposed method was compared with the conventional BOD₅ method. This method was more rapid than the BOD₅ method and the results obtained by the former were in good agreement with those obtained by the latter. The experimental conditions are also discussed in detail.     

聚并苯的链间作用对其导电能力的影响

采用量子化学晶体轨道ＣＮＤＯ／ ２ 方法,在考虑聚并苯链间作用的基础上对聚并苯双链模型的电子结构进行计算和讨论．结果表明：聚并苯链处于不同相对位置的链间作用对聚并苯的电荷分布规律及能带结构均有一定影响,位置不同,影响不同．从聚并苯的能带结构可以得出：聚并苯是有较小能隙、良好本征导电性能的半导体材料,考虑链间作用,对能带结构特征未有大的改变,能隙等值略有修正,导电能力有所加强．利用此模型讨论,更接近于晶体的真实结构,对进行聚并苯导电材料的性能改进将有一定帮助．     

Liquid chromatographic retention of homologous alkanes in the two states of C18-bonded reversed phase silicas

Summary LiChrosorb Si100 densely grafted with octadecylmonofunctional reagents and the similar commerical LiChrosorb RP 18 have been studied in RP-HPLC, with water-methanol mobile phases at different temperatures. They exhibit a phase transition revealing two different states of bonded film as we have previously shown on densely grafted C18 or C22 macroporous silicas.The measurement of the capacity factors of the alkane homologous series indicated a discontinuity in the plot (logK, N) at a critical number whose value is dependent on temperature. Two different forms of these curves can be observed above and below the transition, revealing the influence of bonded film state on the retention mechanism.     

叔醇脱水成烯反应的溶剂化能力与介电常数的关系

我们用Fe_2(SO_4)_3·xH_2O为催化剂,对2-甲基-2-已醇脱水生成烯烃反应的溶剂化能力及其动力学做了研究,测定了20种不同溶剂中的反应速率常数和以丙至辛6种直链醇为溶剂于不同温度下反应的速率常数,确定了溶剂化能力与溶剂介电常数之间的线性关系。这方面工作尚未见报道。     

Length of the flooded zone in the column inlet and evaluation of different retention gaps for capillary gas chromatography

In on-column or in splitless injection with recondensation of the solvent, the length of the flooded zone in the column inlet depends primarily on the wettability of the internal wall of the inlet. For columns with a coated inlet this explains why peak distortion due to band broadening in space by a certain sample volume is pronounced in one case and hardly observable in another. Glass or fused silica capillaries silylated with diphenyltetramethyldisilazane were found to give optimal retention gaps. They combine thorough and thermostable deactivation with good wettability and low retention power. On the other hand it is very easy to deactivate fused silica capillaries with Carbowax. The resulting retention gaps are suitable for a wide range of applications and are particularly attractive for the analysis of dirty samples which require frequent replacement of the inlet.