Effect of melting parameters during synthesis on the structure and properties of tin fluoride phosphate glasses

FTIR and Raman spectroscopy indicate the glass structure during synthesis of tin fluoride phosphate glass was pyrophosphate, mainly built up from Q1 end groups with a low concentration of Q2 polymeric chains. However, sub-optimal melting produced significantly higher concentrations of orthophosphate Q0 structural units. The variationsinNHandP-OHvibrationsinthespectrarevealedthatacriticaltimeandtemperatureofmeltingwere necessary for the conversion of NH4H2PO2 to produce sufficient P2O5 for glass forming. During melting, P2O5 and SnF2 form a low-temperature melt, which facilitates melting of the SnO and promotes the formation of a more stable glass structure. The fluorine breaks the PeOeP bonds and induces depolymerisation. The density of the glass reached a maximum at 450°C for 25min driven by the need for conversion of NH4H2PO4 to P2O5 and miscibility of SnO in the melt. Inadequate melting times and temperatures gave low Tg values because of weak FeSn and FeP linkages. Glass stability improved with melting due to increased P2O5 and SnO miscibility enabling stronger SneOeP linkages. The results show that melting conditions during synthesis strongly influence critical glass properties and future industrial scale-up will require an understanding of optimum processing

Characterization of PVDF with Raman spectroscopy : from off-line to on-line measurements

International audienc

Crystallization monitoring of PVDF α- and β-phases by Raman Spectroscopy and DSC analysis

International audienc

Caractérisation de films PVDF par spectroscopie Raman : une étude off-line vers une étude on-line

National audienc

Analyse vibrationnelle at-line/on-line en milieu industriel

National audienceFrom a technological point of view, vibrational spectroscopies techniques have evolved greatly in recent years. They are faster, have better spectral and spatial resolutions and are more sensitive. In addition, when combined with statistical analysis methods, they can be used for at-line/on-line measurements with times compatible with industrial processes. These technological developments (more powerful sources, more sensitive detectors, use of optical fibers, etc.) lead to the miniaturization of instruments, which can now be used in industrial or hostile environments. The miniaturization of measurement systems often results in less performance than on laboratory devices. It is therefore necessary to carry out a study on samples taken from the industrial process in order to identify the spectroscopic parameter(s) related to the physico-chemical properties of interest and then to build a model adapted to the lower performance of the onsite equipment. It is this compromise of performance of the sensor/efficiency/price that must be optimized.D'un point de vue technologique, les techniques de spectroscopies vibrationnelles ont fortement évolué ces dernières années. Elles sont plus rapides, ont de meilleures résolutions spectrale et spatiale et sont plus sensibles. De plus, associées à des méthodes d'analyses statistiques, elles permettent des mesures at-line/on-line avec des temps compatibles avec les procédés industriels. Ces évolutions technologiques (sources plus puissantes, détecteurs plus sensibles, utilisation de fibres optiques, etc.) conduisent aussi à la miniaturisation des instruments qui peuvent désormais être utilisés dans des environnements industriels ou hostiles. La miniaturisation des systèmes de mesure entraine des performances souvent moindres que sur des appareils de laboratoire. Il est donc nécessaire de réaliser une étude amont sur des prélèvements du procédé industriel afin d'identifier le(s) paramètre(s) spectroscopique(s) lié(s) aux propriétés physico-chimiques d'intérêt et ensuite de construire un modèle pouvant être adapté aux performances moindres de l'équipement sur site. C'est ce compromis performance du capteur/efficacité/prix qu'il faut optimise

Thermal behavior of PVDF/PMMA blends by differential scanning calorimetry and vibrational spectroscopies (Raman and Fourier-Transform Infrared)

International audiencePVDF/PMMA blend exhibits a complex DSC thermogram due to the presence of multiple crystalline phases. This paper shows that Raman and FTIR spectroscopies allow a better interpretation of the thermogram, especially when the sample is heated above the glass transition temperature leading to recrystallization.Use of vibrational spectroscopies, such as Raman and Fourier Transform Infrared (FTIR), during the heating of the polymer gives access to its thermal micro-structural evolution. By this approach, it was possible to discriminate the two crystalline phases initially present in the samples (α and β phases) from the global signal of the whole crystalline phase extracted from the DSC curves. Moreover, crystallization of a third phase (γ-phase) was evidenced using FTIR. Results clearly show that the γ crystallization is a phase transformation from both α- and β-phases.Further to these results, recrystallization and melting of each crystalline phase has been characterized precisely