RESUMEN
Semi-crystalline polymers exhibit microphase separation into crystalline and amorphous domains characterized by multiple structural levels with sizes ranging from ångströms to hundreds of nanometres. The combination of small-angle (SANS) and wide-angle (WANS) neutron scattering on the same beamline enables reliable in situ characterization of such materials under application-relevant conditions, with the unique advantage of contrast variation by controlled labelling, allowing the structure of such multi-component systems to be resolved in detail. This paper reports a structural analysis performed on deuterated polymer membranes based on syndiotactic polystyrene (sPS) using an extended Q-range SANS and WANS combination, always with the same neutron scattering instrument, either a pinhole SANS diffractometer installed at a research reactor or a 'small- and wide-angle' time-of-flight diffractometer installed at a neutron spallation source. sPS is a semi-crystalline material that becomes hydrophilic and proton conducting when suitable functionalization is achieved by thin film sulfonation, and can form various co-crystalline complexes (clathrates) with small organic molecules stored in the crystalline phase as guests in the vacancies between the polymer helices. Therefore, this material is interesting not only for its conducting properties but also for its versatility as a model system to evaluate the usefulness of extended Q-range neutron scattering in such studies. Variation of neutron contrast was achieved in the amorphous hydrophilic phase by using H2O or D2O to hydrate the membranes and in the crystalline phase by loading the clathrates with deuterated or protonated guest molecules. The experimental approach, the advantages and limitations of the two types of instrumentation used in such analyses, and the main results obtained with respect to the structural characterization of sulfonated sPS membranes under different hydration and temperature conditions are reported, and the potential of this method for similar structural studies on other semi-crystalline polymeric materials is discussed.
RESUMEN
Non-destructive characterization of decorated porcelain artifacts requires the joint use of surface-analytical methods for the decorative surface pattern and methods of high penetration depth for bulk-representative chemical composition. In this research, we used position-sensitive X-ray Fluorescence Spectrometry (XRF) and Prompt-gamma activation analysis (PGAA) for these purposes, assisted by 3D structured-light optical scanning and dual-energy X-ray radiography. The proper combination of the near-surface and bulk element composition data can shed light on raw material use and manufacturing technology of ceramics.
RESUMEN
Turquoise covered mosaic objects - especially masks - were attractive components of treasures transported to Europe from Mexico after the fall of the Aztec Empire in the 1500s. According to our present knowledge, the mosaic masks were manufactured for ritual purpose. The main material of mosaics, the turquoise was a high-prestige semi-precious stone among Mexican native people. During the 20th century, such objects derived both from illegal treasure hunting and documented archaeological excavations. The aim of our research was the authentication of a turquoise covered Aztec wooden mask, which presumably originates from the Tehuacán Valley, Mexico and exchanged by the Museum of Ethnography, Budapest, in 1973. The detailed and complex analytical investigation of the mask is a curiosity. To reveal the origin of the object, UV photographs were taken, the wooden base was subjected to biological studies and C-14 dating, the organic glue fixing the tesserae and the inorganic mosaic tesserae were investigated by non-destructive chemical, FT-IR and Raman spectroscopic methods. Our investigations determined that the mask of the Museum of Ethnography was made of an alder species of tree and its age is AD 1492-1653. The light-coloured covering mosaic lamellae were identified as alabaster and claystone. Comparing the turquoise tesserae cover with reference materials, their chemical composition has been clearly differentiated from most of the well-known turquoise sources of the US Southwest. Based on our results, the Aztec mask of the Museum of Ethnography proved to be an original piece of art from the 15th-17th century.