Effects of the copolymer microstructure on the morphology of polyethylene–poly(ethylene‐co‐α‐olefin) blends

The effects of the copolymer microstructure on the morphology evolution in polyethylene/poly(ethylene‐co‐α‐olefin) blends were investigated. Microscopy revealed that the melt‐phase morphology, inferred from the solid‐state morphologies of annealed and quenched samples, was strongly affected by the copolymer structure, that is, the branch content and branch length. Higher molecular weight α‐olefin comonomer residues and residue contents in the copolymers led to faster coarsening of the morphology. The molecular weight of the polyethylene and the copolymers affected the coarsening rates of the morphology, principally through its influence on the melt viscosity. The effects of the molecular weight were largely explained by the normalization of the coarsening rate data with respect to the thermal energy and zero‐shear‐rate viscosity. Thus, the effect of the molecular weight on the compatibility of the blends was much smaller than the effects of the branch length and branch number. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 965–973, 2004     

脂肪乳剂Intralipid代谢产物的高效液相色谱测定

本文介绍了利用ＨＰＬＣ色谱柱前衍生化技术简便，正确和灵敏地测定血清中游离脂肪酸的方法。在最佳条件下，一些脂肪酸的最低检知量为０．０４μｇ。方法已用于脂肪乳剂Ｉｎｔｒａｌｉｐｉｄ在诱发急性坏死性胰腺炎动物体内代谢产物测定。     

Immobilized polysiloxanes as stationary phases for high-performance liquid chromatography and solid phase extraction

Polysiloxanes immobilized onto the surfaces of porous silica particles have proven to be good stationary phases for the separation of multiresidues of pesticides and their metabolic/degradation products by reversed-phase high-performance liquid chromatography (RP-HPLC). Similar materials have proven effective for pre-concentration and clean-up procedures using solid phase extraction. The present paper describes the preparation and some applications of several of these packing materials.     

LC-MS/MS method for the confirmatory determination of aromatic amines and its application in textile analysis

A confirmation method for the determination of 18 aromatic amines originating from azo dyes after reductive cleavage was developed. The method is based on the use of high-performance liquid chromatography/tandem mass spectrometry with atmospheric-pressure chemical ionization. For the identification of the analytes one precursor ion and two daughter ions (multi-reaction monitoring, MRM) were selected and the LC-MS/MS parameters optimized to obtain high sensitivity and selectivity. The linear ranges varied from 0.1–1 to 30–50 g mL^–1 with correlation coefficients of 0.99 or better. The applicability of the method to determine o-tolidine (3,3-dimethylbenzidine) and 3,3-dimethoxybenzidine in textiles following reductive cleavage of acid red 114, trypan blue, and Chicago sky blue 6B was demonstrated.     

The application of chromatography to the analysis of pharmaceutical creams

Summary The application of GLC, HPLC and TLC to the analysis of pharmaceutical creams is discussed with special attention to sample clean-up. The results of the determination of hydrocortisone acetate, salicylic acid, benzoic acid, diethyl stilbestrol, chloramphenicol, diphenhydramine HCl, tretinoin and some cream base components by reversed phase HPLC are given.Presented at the 14th International Symposium on Chromatography London, September, 1982     

Design and Theoretical Study of Nickel Catalysts for Syndiotactic Polyolefins

A nickel catalyst was nodeled with ligand L^2,[NH=CH-CH=CH-0]^-,which should have potential use as a syndiotactic plyolefin catalyst,and the reaction mechanism was studied by theoretical calculations using the density functinal method at the B3LYP/LANL2MB level.The mechanism involves the formation of the intermediate [NiL^2Me]^ ,in which the metal occupies a T-shaped geometry.This intermediate has two possible structures with the methyl group trans either to the oxygen or to the nitrogen atom of L^2.The results show that both structures can lead to the desired product via similar reaction paths,A and B.Thus,the polymerization could be considered as taking place either with the alkyl group occupying the position trans to the Ni-0 or trans to the Ni-N bond in the catalyst.The polymerization process thus favors the catalysis of syndiotactic polyolefins.The syndiotactic synthesis effects could also be enhanced by varations in the ligand substituents.From energy considerations,we can conclude that it is more favorable for the methyl ttrans-O position to form a complex than to occupy the trans-N position.From bond length considerations,it is also more favoured for ethene to occupy the trans-O position than to occupy the trans-N position.     

Donator-Acceptor Komplex Chromatographie Tetrachlorphthalimidopropylsilica,eine neue,chemisch gebundene Phase,geeignet zur Trennung von Kohleverflüssigungsprodukten und anderen technischen aromatischen Gemischen mit der Hochleistungsflüssigkeitschromatographie

Summary The preparation of a new tetrachlorophthalimidophase for HPLC is described. The capacity ratios (k) of about forty aromatics and twenty nitrogen-containing aromatics were determined. Most of the compounds used were alkylated. It was shown that the aromatics were eluted according to the number of rings, only slightly influenced by the substituents. A similar elution order was not observed with the heteroaromatics. The performance of the stationary phase is demonstrated, performing separations of coal liquids and other aromatic mixtures.

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Donator-Acceptor Komplex Chromatographie Tetrachlorphthalimidopropylsilica, eine neue, chemisch gebundene Phase, geeignet zur Trennung von Kohleverflüssigungsprodukten und anderen technischen aromatischen Gemischen mit der Hochleistungsflüssigkeitschromatographie

Zusammenfassung Es wird die Synthese einer neuen Tetrachlorphthalimid-Phase für die HPLC beschrieben. Anhand von Elutionsversuchen mit über vierzig Aromaten und zwanzig N-Heteroaromaten, die größtenteils alkyliert waren, konnte gezeigt werden, daß kondensierte Aromaten unabhängig vom Alkylierungsgrad streng nach der Zahl der aromatischen Ringe eluiert werden, was für die Heterocyclen nicht zutrifft. Die Kapazitätsverhältnisse (k) der untersuchten Verbindungen werden angegeben. Die Leistungsfähigkeit der Phase wird an der chromatographischen Trennung von Kohleverflüssigungsprodukten und anderen komplexen, aromatischen Gemischen demonstriert.

     

High-performance liquid chromatography of sulfonamides and quinolones on p-tert-butyl-calix[6]arene-bonded silica gel stationary phase

The high-performance liquid chromatographic behavior of some sulfonamides and quinolones was studied on a p-tert-butyl-calix[6]arene-bonded silica gel stationary phase. The effect of mobile phase variables such as methanol content, ionic strength and pH on their chromatographic behavior was investigated. The retention behavior of sulfonamides on the stationary phase was compared with that on both Zorbax C₁₈-bonded silica gel and γ-(ethylenediamino)propyltriethoxylsilane-bonded silica gel (diamino-bonded phase). The retention mechanism of sulfonamides and quinolones on the stationary phase was also discussed. The results indicate that the stationary phase behaves as a reversed-phase packing and its separation selectivity is much better than that of not only Zorbax C₁₈ phase but also diamino-bonded phase. Some sulfonamides and quinolones were separated on the stationary phase, but the separation of sulfonamides is far more successful.     

马来酸酐与聚烯烃接枝产物的表征

综述了马来酸酐与聚烯烃接枝产物的多种表征手段，重点分析了纯化处理，化学滴定以及红外分析方法的表征原理，应用和改进方法。