Pulsed laser deposited alumino-silicate thin films and amorphous chalcogenide/alumino-silicate structures

International audienceAlumino-silicate coatings and structures formed from alumino-silicate and amorphous chalcogenide submicrometer layers were prepared by pulsed laser deposition. Fabricated thin films were characterized in terms of their structure, morphology, topography, chemical composition, optical properties, and basic anticorrosive functionality. Prepared coatings are amorphous, smooth, without micrometer-sized droplets, with chemical composition close to parent targets. Spectral dependencies of refractive indices and extinction coefficients were derived from variable angle spectroscopic ellipsometry data. Amorphous chalcogenide/alumino-silicate structures present large refractive index differences of individual layers (Δn ~ 1.2 at 1550 nm) which could be useful for optical systems working at infrared telecommunication band wavelengths. Basic anticorrosion data of alumino-silicate layers show promising anticorrosion behavior

Nanocompósitos de PVC com argila organicamente modificada: efeitos do processamento e do método de incorporação da argila PVC/organically modified montmorillonite nanocomposites: effects of processing and clay incorporation methodology

Nanocompósitos de poli(cloreto de vinila) (PVC) flexível com argila organicamente modificada (O-MMT) foram preparados utilizando-se diferentes metodologias de produção, de forma a estudar seus efeitos sobre o grau de intercalação/esfoliação da argila. A morfologia dos nanocompósitos obtidos foi avaliada através de difratometria de raios X (DRX) e microscopia eletrônica de transmissão (MET). Foram também avaliadas propriedades de tração e estabilidade térmica estática das formulações preparadas. Nanocompósitos de microestrutura híbrida intercalada/parcialmente esfoliada foram obtidos, independentemente do composto de PVC ter sido processado a partir do pó ou granulado (extrudado previamente), e do método de incorporação da O-MMT à resina de PVC (diretamente no misturador intensivo ou pré-esfoliada em DIDP/OSE a quente). Os plastificantes, presentes na formulação do composto de PVC flexível, exerceram um papel importante no processo de intercalação e esfoliação da argila, facilitando a formação dos nanocompósitos.<br>Nanocomposites of poly(vinyl chloride) (PVC) and an organically modified montmorillonite (O-MMT) were prepared using different production approaches to assess possible effects on the degree of clay intercalation/exfoliation. The morphology of the nanocomposites was studied using X ray diffratometry and transmission electron microscopy. Tensile properties and static thermal stability were also evaluated. Hybrid intercalated/partially exfoliated nanocomposites were obtained, regardless of whether the PVC compound was processed from the powder (dry blend) or granulated (extruded) samples, or of the methodology used for incorporation of O-MMT into the PVC compound (directly in the intensive mixer or pre-exfoliated in a hot mixture of DIDP/ESO). The plasticizers, present in the flexible PVC compound, exerted an important role in the process of intercalation and exfoliation of the clay, helping the formation of the nanocomposites