Korrosion

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Effects of molecular mass and surface treatment on adsorbed poly(methyl methacrylate) on silica

The behavior of relatively monodisperse adsorbed poly(methyl methacrylate) (PMMA) samples, from 19 to 587 kDa on silica, was studied using modulated differential scanning calorimetry and FTIR. On untreated Cab? O? Sil silica, the glass transition temperatures (T_gs) were higher (by around 30 °C), and the transitions were significantly broader (by a factor of 5–6) than those for the corresponding bulk samples. While the T_gs for the bulk polymers showed the expected dependence on molecular mass, the polymers on untreated silica showed little dependence, i.e., at the same adsorbed amounts, the glass transitions were very similar. The FTIR spectra of the adsorbed PMMA (on untreated silica) showed the presence of at least two resonances, one for the bound (hydrogen bonded to surface silanols) and another for free carbonyls. Fitting of the spectra allowed the estimation of the bound fractions of carbonyls that were dependent on the adsorbed amount, but not molecular mass. On Cab? O? Sil treated with hexamethyldisilizane (HMDS), the adsorbed PMMA exhibited glass transition behavior with little molecular‐mass dependence; the T_gs for the different PMMA samples were very similar to those of the high‐molecular mass bulk polymer, but with additional broadening of about a factor of 2. FTIR spectra for the PMMA samples on the treated silica did not show significant amounts of any of the hydrogen‐bonded carbonyl groups. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 649–658, 2008     

Zur Bestimmung der Thonerde neben Eisenoxyd und Phosphors?ure

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Ueber eine directe Trennung des Mangans vom Eisen

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Phosphorbestimmungsmethoden

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Extension of the Quantum Mechanical Principle of Superposition to Non-Identical States with Short Life Times

We apply the principle of superposition to two quantum mechanical states of which one has a short life time 1/Γ. They must be identical, but may have a small difference in energy-momentum comparable to Γ. This produces new effects resulting from the linear relationship that appears between the S-matrix element and the production cross section of the decay products of the short lived state. An optical theorem for diffraction dissociation processes is proposed. This mechanism also provides a measure of the non-orthogonality between unstable particles that are eigenstates of a non-Hermitian Hamiltonian. Talk presented on the Workshop on Resonances and Time Asymmetric Quantum Theory, Jaca (Spain), 30 May to 4 June 2001     

Sticky model of charged colloids

Summary We use the Sticky Electrolyte Model, which we solved before in PY/MSA, to obtain the equation of state of a charge colloid taking into account both sticky and charge contribution. Paper presented at the I International Conference on Scaling Concepts and Complex Fluids, Copanello, Italy, July 4–8, 1994.     

A technique for generating shear waves in cylindrical shells under radial impact

Experimental techniques are developed to study and measure the shear-wave velocity in an aluminum cylindrical shell subjected to a radial impact. The radial impact is obtained by exploding an electrical detonator inserted in plastic plugs mounted on the end of the shell. Strain gages, mounted on the outside surface of the shell at various axial locations, are used to obtain oscilloscope traces from which the shear-wave velocity can be calculated.