Melting behaviors,crystallization kinetics,and spherulitic morphologies of poly(butylene succinate) and its copolyester modified with rosin maleopimaric acid anhydride

This article investigated the melting behaviors, crystallization kinetics, and spherulitic morphologies of poly(butylene succinate) (PBS) and its copolyester (PBSR) modified with rosin maleopimaric acid anhydride, using wide‐angle X‐ray diffraction, differential scanning calorimeter (DSC), and polarized optical microscope. Subsequent DSC scans of isothermally crystallized PBS and PBSR exhibited two melting endotherms, respectively, which was due to the melt‐recrystallization process occurring during the DSC scans. The equilibrium melting point of PBSR (125.9 °C) was lower than that of PBS (139 °C). The commonly used Avrami equation was used to describe the isothermal crystallization kinetics. For nonisothermal crystallization studies, the model combining Avrami equation and Ozawa equation was employed. The result showed a consistent trend in the crystallization process. The crystallization rate was decreased, the perfection of crystals was decreased, the recrystallization was reduced, and the spherulitic morphologies were changed when the huge hydrogenated phenanthrene ring was added into the chain of PBS. The activation energy (ΔE) for the isothermal crystallization process determined by Arrhenius method was 255.9 kJ/mol for PBS and 345.7 kJ/mol for PBSR. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 900–913, 2006     

Reinforcement effect of MAA on nano‐CaCo3‐filled EPDM vulcanizates and possible mechanism

Methacrylic acid (MAA) was used as in situ surface modifier to improve the interface interaction between nano‐CaCO₃ particle and ethylene–propylene–diene monomer (EPDM) matrix, and hence the mechanical properties of nano‐CaCO₃‐filled EPDM vulcanizates. The results showed that the incorporation of MAA improved the filler–matrix interaction, which was proved by Fourier transformation infrared spectrometer (FTIR), Kraus equation, crosslink density determination, and scanning electron microscope (SEM). The formation of carboxylate and the participation of MAA in the crosslinking of EPDM indicated the strong filler–matrix interaction from the aspect of chemical reaction. The results of Kraus equation showed that the presence of MAA enhanced the reinforcement extent of nano‐CaCO₃ on EPDM vulcanizates. Crosslink density determination proved the formation of the ionic crosslinks in EPDM vulcanizates with the existence of MAA. The filler particles on tensile fracture were embedded in the matrix and could not be observed obviously, indicating that a strong interfacial interaction between the filler and the matrix had been achieved with the incorporation of MAA. Meanwhile, the presence of MAA remarkably increased the modulus and tensile strength of the vulcanizates, without negative effect on the high elongation at break. Furthermore, the ionic bond was thought to be formed only on filler surface because of the absolute deficiency of MAA, which resulted in the possible structure where filler particles were considered as crosslink points. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 1226–1236, 2006     

Enhanced sensitivity in flow injection analysis using a long pathlength liquid waveguide capillary flow cell for spectrophotometric detection.

Incorporation of a liquid waveguide capillary flow cell into a flow injection instrument enhances the sensitivity of flow injection analysis with spectrophotometric detection by two orders of magnitude. Nitrite determination at nM levels has been used to demonstrate the feasibility of this novel technique for trace analysis. Combining the long pathlength spectrophotometry with flow injection analysis, this technique has advantages of low detection limit, good precision and high sample throughput.     

Chiral separation of synthetic vicinal diol compounds by capillary zone electrophoresis with borate buffer and beta-cyclodextrin as buffer additive.

The investigation on capillary electrophoretic enantioseparation of six synthetic compounds containing vicinal diol groups has been undertaken to acquire the optimum conditions using native beta-cyclodextrin (beta-CD) as chiral selector and borate as a background electrolyte. The separation was carried out in an uncoated capillary (58.5 cm x 75 microm i.d., effective length 48.5 cm) and the effects of several important factors were investigated in detail. The results showed that beta-CD as a chiral selector exhibited good enantioselectivity and that the enantioseparation was greatly influenced by the structure of the diols, the borate concentration and the buffer pH. The optimum performance was obtained for the chiral vicinal diols under the conditions of 200 mM borate buffer of pH 9.8 containing 1.7% beta-CD at an applied voltage of 15 kV and a capillary temperature of 20 degrees C. Under the conditions, four diols were baseline separated with fast analysis time and the good theoretical plate numbers (above 10 x 10(4)) and favorable migration-time reproducibilities (RSDs below 3.0%) were obtained. The separation results were satisfactory.     

Determination of 17 kinds of banned organochlorine pesticides in water by activated carbon fiber-solid phase microextraction coupled with GC-MS.

Activated carbon fiber (ACF) as extraction fiber for solid-phase microextraction (SPME) and its application for the analysis of banned organochlorine pesticides (OCPs) were investigated. Firstly, ACF was activated by different concentration of zinc chloride, which indicated that ACF activated by 60% zinc chloride had a reasonable specific surface area, pore volume and pore distribution. Secondly, the parameters for the ACF-SPME procedure, the adsorption and desorption conditions, were also optimized when coupled with gas chromatography-mass spectrometry (GC-MS). Thirdly, the ACF-SPME was used to analyze 17 kinds of OCPs in water. The linearity of most pesticides was found to be between 0.2 and 50 microg/l with GC-MS under the selected ion monitoring (SIM) acquisition mode. The limits of detection (LOD) at the sub microg/l were obtained. The work demonstrated here shows that ACF is a promising alternative for the SPME procedure.     

微型硅谐振式力传感器的振动分析

介绍了谐振式力传感器的工作原理，并从理论上和实验上对中科院合肥智能所研制的第一代微型硅谐振梁（３×０．４×０．０４５ｍｍ＾３）式测力传感器进行了全面的振动分析，所得结构为其进一步优化设计提供了科学根据，文中使用的实验分析方法，为其它微小物体的动态和识别提供了一条有效途径。     

酚醛型吸附树脂对水体系中吡啶和N,N-二甲基苯胺的吸附性能研究

研究了酚醛型吸附树脂在水体系中对吡啶和N，N-二甲基苯胺的静态和动态吸附行为．结果表明，在水中树脂对吡啶和N，N-二甲基苯胺的吸附主要以疏水吸附机理进行；吸附吡啶和N．N-二甲基苯胺的初始阶段，即达到38．3～48．9％平衡吸附时，吸附速率数据和半经验速率方程很吻合：酚醛型吸附树脂等温吸附吡啶和N，N-二甲基苯胺的平衡吸附数据符合Langmuir方程，相关系数在0．99以上，酚醛型吸附树脂吸附吡啶和N，N-二甲基苯胺属单分子层吸附：用80％的乙醇溶液作洗脱剂来洗脱吸附吡啶已达饱和的JDW-2树脂，效果是很理想的．在3．6个床体积内洗脱率达91．52％，4．8个床体积内洗脱率达到94．85％。表明酚醛型吸附树脂具有优良的洗脱性能．     

Determination of inosine 5′-monophosphate and guanosine 5′-monophosphate in pig feed by capillary zone electrophoresis

A capillary zone clectrophoresis method was developed for the determination of IMP and GIMP, commonly used as flavor enhancers in poultry feed, in a real sample of complex composition. A baseline separation of inosine 5′-monophosphate and guanosine 5′-monophosphate was achieved within 10 min and the other components in the sample did not interfere with the separation. Quantitative results obtained from pig feed samples are presented. The separation conditions and experimental reproducibility are also discussed.