Beiträge zur galvanisierung von polymeren, 5. Untersuchungen zur morphologie der galvanischen kupferschicht

The structure of a 15–20 μm thick copper layer, which is deposited electrochemically on copolymers of acrylonitrile, butadiene and styrene from bathes containing additives is extremely distorted. This is caused by microstresses and paracrystalline lattice distortions. On the other hand, the structure of the copper layer deposited from a pure bath is independent of the chemical pre-conditioning of the polymer surface, necessary for plating, and equal to that of a high crystalline pure copper.     

Antibacterial Effect of Gaseous and Aqueous Ozone in Root Canals Infected by Enterococcus Faecalis

The present study evaluated the antibacterial effects of aqueous and gaseous ozone in human root canals infected with Enterococcus faecalis. Infected root canals were divided into two control groups (saline, sodium hypochlorite) and three experimental groups (manual or ultrasonic technique of aqueous and, gaseous ozone). Disinfection procedures were performed, remaining microbial colonies were counted and data were evaluated. Sodium hypochlorite showed the highest antibacterial effect on root canals infected with Enteroccous faecalis. Moreover, aqueous ozone with ultrasonic technique appear to be more influential than aqueous ozone with manual technique and gaseous ozone.     

Investigation of ZnO‐release behavior of poly(N‐isopropylacrylamide‐co‐maleic acid)/ZnO composite hydrogels by differential pulse polarography

Poly(N‐isopropylacrylamide‐co‐maleic acid)‐zinc oxide [P(NIPA/MA)/ZnO] composite hydrogels, containing a definite amount of ZnO, were prepared from N‐isopropylacrylamide (NIPA) and maleic acid (MA) monomers with 0–31.15 mol % MA in aqueous saturated zinc oxide solutions by radiation‐induced polymerization and gelation using γ rays from a ⁶⁰Co source. The amounts of released ZnO from these composite hydrogels were determined by differential pulse polarography (DPP) using the characteristic peaks obtained at about –1,000, ?1,050, and –1,300 mV at pH 2.0, 5.5, and 7.05, respectively. It was found that the ZnO‐release behavior of P(NIPA/MA)/ZnO composite hydrogels depended strongly on the MA content and pH of the medium.     

Determination of average molecular weight between crosslinks and polymer–solvent interaction parameters of poly(acrylamide‐g‐ethylene diamine tetraacetic acid) polyelectrolyte hydrogels

Hydrogels containing tetraprotic acid moieties sensitive to pH changes of the swelling medium were prepared from the ternary systems acrylamide/ethylene diamine tetraacetic acid/water by irradiation with γ‐rays at ambient temperature. Gel compositions of poly(acrylamide‐g‐ethylene diamine tetraacetic acid) [P(AAm‐g‐EDTA)] hydrogels were determined by using a differential pulse polarography technique. Equilibrium swelling behavior of these hydrogels was studied using an equation, based on the Flory–Huggins thermodynamic theory, the phantom network theory of James–Guth, and the approaches of Brannon‐Peppas and Peppas, which was modified by the authors for determination of M _c and χ parameters. The equation modified by the authors for the determination of M _c and χ parameters were observed to describe very well the swelling behavior of the charged polymeric network. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 2168–2175, 2004     

纸浆纤维的阳离子化及其研究进展

对纸浆纤维阳离子化的研究进展进行了总结和评述。主要介绍和比较了纸浆纤维阳离子化的3种方法:直接阳离子化法,预聚物耦合法和阳离子高聚物接枝法。讨论了阳离子纤维的助留机理。阳离子纤维和可溶性阳离子聚合物配合使用有助于提高细小纤维和填料的留着率。     

Determination of insecticide pymetrozine by differential pulse polarography/application to lake water and orange juice

A simple, fast and sensitive differential pulse polarographic method (DPP) for the determination of pymetrozine insecticide in pure form, agrochemical formulation, natural water and orange juice samples is proposed. The polarographic behavior of pymetrozine exhibited a double well-defined polarographic peaks at -580 and 950mV (versus SCE), respectively. The peak potentials were strongly pH-dependent in that they shifted to more negative values with increasing pH. The polarographic reduction corresponding to the first peak at pH 2.0 (B-R buffer solution) showed quantitative increments with the additions of standard pymetrozine solution under the optimal conditions and the corresponding peak current was linearly proportional to pymetrozine concentration in the range of 4.97x10(-7) to 7.35x10(-5)molL(-1). The limit of detection (LOD) and limit of quantification (LOQ) were obtained as 1.48x10(-7) and 4.93x10(-7)molL(-1), respectively. The mean recoveries of the 5.0x10(-6)molL(-1) pymetrozine spiked to lake water and orange juice were (4.89+/-0.23)x10(-6) and (4.97+/-0.19)x10(-6)molL(-1) at 95% confidence level, respectively. The method was extended to the determination of pymetrozine in agrochemical insecticide formulation Plenum and accuracy was in agreement with that obtained by HPLC comparison method. Influences of some interfering ions and some other pesticides were also investigated. The mechanistic study was not pursued.