GMA熔融接枝EPDM的研究

以甲基丙烯酸缩水甘油酯（ＧＭＡ）为接枝单体，过氧化二异丙苯（ＤＣＰ）为引发剂，对三元乙丙胶（ＥＰＤＭ）进行了熔融接枝，在烃链上引入极性基团，以改善ＥＰＤＭ与极性聚合物的相容性。用差示扫描量热计（ＤＳＣ）研究了ＧＭＡ的聚合温度，用富里叶红外（ＦＴ－ＩＲ）、凝胶渗透色谱（ＧＰＣ）对接枝产物进行了表征。实验结果表明，产物的接枝率和凝胶量可以通过反应条件（温度、时间、反应物组成及加料方式）来控制。     

Manipulation of the Electroosmotic Flow in Glass und PMMA Microchips with Respect to Specific Enzymatic Glucose Determinations

The determination of glucose in microfluidic chips made of glass or PMMA was used as a model for the combination of an enzymatic reaction with the separation of compounds. It was based on the enzymatic oxidation of glucose and the amperometric detection of hydrogen peroxide. Real samples frequently contain compounds, such as ascorbic acid, which may interfere with quantitative glucose determinations. Thus, electrophoretic separation of specific from unspecific signals was envisaged by applying electric fields which are also used to control the flow of liquid via electroosmotic effects. Surface charge densities of the capillaries influence the electroosmotic flow (EOF). They are dependent on the chip material and on the adsorption of components from the background electrolyte. Reversal of the EOF after addition of cetyltrimethylammonium bromide (CTAB) and an increase in EOF after addition of sodium dodecylsulfate (SDS) were observed at lower surfactant concentrations with the PMMA chips rather than with the glass chips. For both chip materials these concentrations were below the critical micelle concentration. Effective separation of H₂O₂ and ascorbic acid was achieved with low CTAB concentrations, which lead to a reduction, but not to a reversal of the EOF. Reversal of the EOF by higher CTAB concentrations or the increase in cathodic EOF by SDS accelerated ascorbic acid transportation and reduced the differences in migration times. Thus, for the specific determination of glucose, glucose oxidase was added together with low CTAB concentrations to the background electrolyte. This avoided interference from ascorbic acid, and data obtained from the analysis of fruit juices showed a good correlation to data obtained from a reference method.     

新型含有机硅二元多嵌段共聚物的研究

报道了聚羟基醚（ＰＨＥ）、聚羟基醚砜（ＰＨＥＳ）、酚酞聚羟基醚（ＰＰＨＥ）和聚对羟基苯乙烯（ＰＨＳ）与端胺基聚二甲基硅氧烷（ＰＤＭＳ）通过羟胺缩合生成ＡＢｍｎ新型结构的可溶性含有机硅二元多嵌段共聚物，ｍ值在１～６之间，详细讨论了反应物浓度对共缩聚反应的影响，并通过分子量测定、红外光谱分析和动态力学分析（ＤＭＡ）技术初步确定了其反应机理、结构和动态力学性能．     

Analysis of the effects of catalytic bleaching on cotton

Hydrogen peroxide can be catalyzed to bleach cotton fibers at temperatures as low as 30°C by incorporating dinuclear tri-μ-oxo bridged manganese(IV) complex of the ligand 1,4,7-trimethyl-1,4,7-triazacyclononane (MnTACN) as the catalyst in the bleaching solution. The catalytic system was found to be more selective under the conditions applied than the non-catalytic H₂O₂ system, showing better bleaching performance while causing slightly lower decrease in degree of polymerization (DP) of cellulose. In order to gain fundamental knowledge of the bleach effect on cotton fibers and cellulose as its main component, especially after catalytic bleaching, X-ray Photoelectron Spectroscopy (XPS) was used to study surface chemical effects. The Washburn method was applied to investigate wetting properties, and liquid porosity was used to obtain pore volume distribution (PVD) plots. Parallel analyzes performed on model cotton fabric, i.e. “clean” cotton fabric stained with morin - a pigment regularly found in native cotton fiber, helped to differentiate between pigment oxidation and other bleaching effects produced on the (regular) industrially scoured cotton fabric. Bleaching was not limited to the chemical action but also affected cotton fiber capillary parameters most likely due to the removal of non-cellulosic materials as well as chain-shortened cellulose.     

Dynamic electrochemical impedance spectroscopy measurements of passive layer cracking under static tensile stresses

Electrochemical impedance spectroscopy allows the examination of corrosion susceptibility and resistance for different construction materials, in particular the determination of the properties of their passive films. This technique makes possible the analysis of electrochemical processes in time domain, including rapid phenomena such as changes in the properties of passive films, but it has never been used for passive layer cracking examination. In many cases, fracture of the passive film under tensile stresses leads to stress corrosion cracking. Therefore, investigations of passive layer cracking on austenitic stainless steels under tensile stresses facilitate the understanding of the mechanism of stress corrosion cracking in these common engineering materials. The effect of static tensile stresses on the passive film cracking behaviour of type 304L stainless steel immersed in 0.5 M NaCl solution at room temperature has been investigated. This paper presents the impedance spectra obtained for 304L stainless steel samples at different potential values.Contribution to the 3rd Baltic Conference on Electrochemistry, Gdansk-Sobieszewo, Poland, 23–26 April 2003Dedicated to the memory of Harry B. Mark, Jr. (28 February 1934–3 March 2003)     

Fire retardant synergism between melamine and triphenyl phosphate in poly(butylene terephthalate)

The fire retardant efficiency of melamine (MA) and triphenyl phosphate (TPP) in poly(butylene terephthalate) (PBT) was studied by the limiting oxygen index (LOI) and the UL94 test. On adding 10 wt. % MA and 20 wt. % TPP, LOI increased from 20.9 to 26.6 and the UL94 V-0 rating was achieved. SEM and DSC analyses show that the fire retardants are compatible with PBT and facilitate crystallization of PBT. The occurrence of an interaction between MA + TPP and PBT was elucidated by TGA, dynamic FTIR, and pyrolysis/GC/MS. MA + TPP changes the degradation path of PBT and modifies the compositions of the gas and condensed-phase products.     

Studies on accelerated sulphur vulcanization of natural rubber using 1-phenyl-2, 4-dithiobiuret/tertiary butyl benzothiazole sulphenamide

The use of binary accelerators has gained tremendous importance since it increases the production rate of the article made of that elastomer. The authors have analyzed the performance of a novel binary accelerator system in the sulphur vulcanization of natural rubber (NR). The vulcanizates resulting from the binary accelerated process obtained good mechanical properties, ageing and swelling resistance. Network characterization of the mixes was done using swelling measurements, stress-strain analysis etc. The chain entanglement density was measured using dynamic mechanical analysis. However the performance is found to be dependent on the relative proportion of mono, di and polysulphidic linkages in the material. The result of the study points out that the proposed system can be active in NR regardless of the vulcanization recipe and temperature. The performance of the new binary system in filled vulcanizates is also studied. Based on the processing, mechanical and chemical characterization an optimum concentration is suggested for the new system.     

Dynamic light scattering and cryogenic transmission electron microscopy investigations on metallo-supramolecular aqueous micelles: evidence of secondary aggregation

Metallo-supramolecular diblock copolymers consisting of a polystyrene (PS) block connected to a poly(ethylene oxide) (PEO) block by a bis(terpyridine)ruthenium complex (PS₂₀-[Ru]-PEO _y ) were used to prepare aqueous micelles. The length of the PS block was kept constant, while two PEOs of different molecular weight were used. The resulting hydrated micelles and aggregates were characterized by a combination of cryogenic transmission electron microscopy (cryo-TEM) and dynamic light scattering measurements. The results were compared to those obtained for a covalent counterpart (PS₂₂-b-PEO₇₀). Cryogenic transmission electron microscopy allowed visualization of the PS core of the micelles. Moreover, the aggregates result from clustering of individual micelles.     

A comparison of two algorithms for warping of analytical signals

The alignment of analytical signals is an important preprocessing step when further analysis (e.g. PCA) requires the same lengths of all of them. Two techniques for alignment of profiles, namely dynamic time warping (DTW) and correlation optimized warping (COW) were tested and compared. The attention was focused on chromatographic and spectroscopic profiles. Simulated and two sets of real data were studied in this study.     

Value function and optimality conditions for semilinear control problems

This paper is concerned with optimal control problems of Mayer and Bolza type for systems governed by a semilinear state equationx(t)=Ax(t) + f(t, x(t), u(t)), u(t) U, whereA is the infinitesimal generator of a strongly continuous semigroup in a Banach spaceX. We prove necessary and sufficient conditions for optimality and then use these conditions to investigate properties of the value function related to superdifferentials. Conversely, we use the value function to obtain criteria for optimality and feedback systems.Work (partially) supported by the Research Project Equazioni di evoluzione e applicazioni fisicomatematiche (M.U.R.S.T.-Italy).