Concentration of nonylphenol and its polyethoxylated derivatives by polymer-mediated extraction

Polymer-mediated extraction based on thermoresponsive precipitation of poly(N-isopropylacrylamide) [PNIPAAm] was applied to the concentration of amphiphilic compounds, nonylphenyl polyethoxylates (NPnEOs), in water. Among these nonionic surfactants, NPnEOs possessing the number, n, of ethoxy unit less than 5 were quantitatively recovered in polymer precipitates when a 0.100-g portion of PNIPAAm was used for a 10 ml sample solution. Torelance limit (30 ppm) against a typical industrial anionic surfactant, sodium dodecylsulfate, strongly suggests the potential to use the present method for practical purposes. After preconcentration, trace nonylphenol and mono-ethoxylated nonylphenol (ppb-level) in a river water sample were successfully determined by high-performance liquid chromatography with ultra-violet photometric detection.     

Low-frequency and high-frequency relaxations in dynamic electric birefringence of poly(γ-benzyl-L-glutamate) in m-cresol

The dc component Δn of the electric birefringence of poly(γ-benzyl-L -glutamate) in m-cresol is measured under an ac electric field at frequencies from 0.5 Hz to 200 kHz for solutions covering the dilute and semidilute regions. The dispersion curve indicates that at low frequencies Δn decreases with increasing frequency (low-frequency relaxation). For high-molecular-weight polymers at high concentration, Δn becomes negative at high frequency and its absolute value decreases with further increase in frequency (high-frequency relaxation). A unified theory for the two relaxations is developed on the basis of a model in which, in the semidilute regime, the rodlike polymer is confined in a cage formed by neighboring polymers and the lifetime of the cage lies between relaxation times of the two relaxations. The low-frequency relaxation is ascribed to end-over-end rotation of the polymer and the high-frequency relaxation to the rotation within a limited angle in the cage. The dependences of relaxation parameters on polymer concentration and molecular weight are reasonably explained by the theory.     

Sulfur-containing polymers. IV. Preparation and properties of poly(sulfenyl thiocarbonates)

Poly(sulfenyl thiocarbonates) have been prepared for the first time by the stepwise condensation of chlorocarbonylsulfenyl chloride with diols and dithiols. The polymers were obtained in high yield. Generally they were crystalline solids and were soluble in chlorinated hydrocarbons. On treatment with benzyl mercaptan in the presence of triethylamine, the polymers afforded a diol, carbonyl sulfide, and a disulfide compound. This reaction was extended to the preparation of alternating copolydisulfides.     

Bounds on mass transport of flow on an inclined plate

Zusammenfassung In der vorliegenden Arbeit wird das Variationsproblem, welches die Schranken für den Durchfluss in turbulenter Strömung auf einer geneigten Platte bestimmt, nach Busse [2] abgeleitet. Es wird die symmetrische Natur der Lösung des Variationsproblems für die ebene Poiseuille-Strömung geprüft. Dies zeigt einerseits Ähnlichkeit und andrerseits Unterschiede zwischen dem Problem der ebenen Poiseuille-Strömung und der Strömung auf einer geneigten Platte.