Compatibilization effect of TiO2 nanoparticles on the phase structure of PET/PP/TiO2 nanocomposites

Polyethylene terephthalate (PET)/Polypropylene (PP)/TiO₂ nanocomposites were prepared by compounding a PP/TiO₂ nanocomposite premix with PET in absence and presence (up to 6 vol %) of maleic anhydride grafted polypropylene (PP‐g‐MA). In absence of PP‐g‐MA, the TiO₂ nanoparticles were mainly located at the PET/PP interface and to a lesser extent in the dispersed PET droplets. As the TiO₂ nanoparticles were coated by polyalcohol their surface could react with PP‐g‐MA and thus improving the compatibilization with PP. Therefore in presence of PP‐g‐MA the TiO₂ nanoparticles were preferentially located in the PP. The incorporated TiO₂ nanoparticles exerted a compatibilization effect on the PET/PP blend. Depending on the location of TiO₂ three different compatibilization mechanisms were proposed to be at work: (1) Locating at the interface, the TiO₂ nanoparticles decrease the free energy of mixing, and thus increase the thermodynamic stability of the nanocomposites; (2) The TiO₂ nanoparticles at the interface also prevent the coalescence of PET droplets; (3) Preferentially located in the PP matrix, the TiO₂ nanoparticles decreased the viscosity ratio which facilitated the droplet breakup of PET. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 1616–1624, 2009     

Twisted products in pseudo-Riemannian geometry

Twisted products are generalizations of warped products, namely the warping function may depend on the points of both factors. The two canonical foliations of a twisted product are mutually perpendicular and their leaves are totally geodesic, resp. totally umbilic. The main result is a decomposition theorem of de Rham type: If on a simply connected, geodesically complete pseudo-Riemannian manifoldM two foliations with the above properties are given, thenM is a twisted product.     

Determination of molybdenum in plant reference material by thermal-ionization isotope-dilution mass spectrometry

Summary An analytical method is described for the determination of the concentration and the isotopic composition of molybdenum in plant samples using thermal ionization mass spectrometry. After microwave acid digestion and liquid-liquid extractive separation with Amberlite LA-2, the molybdenum isotopes are measured as MoO ₃ ^– -ions in a quadrupole mass spectrometer. In all cases, the relative standard deviation of the measurements of both natural and spike molybdenum was better than 3% for all ratios measured. The concentration of molybdenum found in three different plant reference materials agreed well with the certified values.     

UV and IR derivative spectroscopy of novolac layers

Thin solid layers of halophenol and cresol novolacs were investigated by UV derivative spectroscopy. Structural differences can be identified. Derivative spectroscopy was useful for the analysis of the OH stretching region of cresol novolac/PMMA blends. Three sub-bands were discussed and a high amount of intramolecular H-bonding for p-cresol novolac was deduced.     

Conversion processes in superheavy and giant atoms

Conversion of bound state electrons and internale ⁺,e ^?-pair creation in superheavy and giant atoms are investigated. We consider various nuclear transitions of multipolaritiesE0, EL andML (L≧1) in superheavy atoms with Z>109. We are concerned in particular with the pecularities of conversion processes in supercritical systems. Our theoretical studies are confronted with the prominent peak structures observed in positron spectra of very heavy collision systems.