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Saint-Christol-lès-Alès, France

Rinawa K.,Indian Institute of Technology Delhi | Maiti S.N.,Indian Institute of Technology Delhi | Sonnier R.,Center Des Materiaux Of Grande Diffusion | Lopez Cuesta J.-M.,Center Des Materiaux Of Grande Diffusion
Polymer Bulletin | Year: 2015

The viscoelastic behaviour of PA12/SEBS-g-MA blends was studied. Time sweep, amplitude sweep, and frequency sweep tests were analysed by the use of parallel-plate rheometer. Time sweep test shows time-independent viscoelastic behaviour of the polymer and blends during the entire duration of test. The critical shear strain was higher for PA12 as compared to that of SEBS-g-MA and the blends in amplitude sweep test. However, the plateau modulus was higher for SEBS-g-MA as compared to PA12. The complex viscosity, dynamic storage, and loss moduli of PA12 increased with the addition of SEBS-g-MA as a consequence of phase interaction between them. The influence of phase morphology of blend composition on their rheological properties was also examined. The blend showed a transformation from liquid-like to solid-like behaviour. The decrease in viscosity for PA12 and blends was observed with increasing temperature. The van Gurp plots was successfully used to validate time–temperature superposition principle (TTS) for PA12, SEBS-g-MA and blend compositions. PA12 holds TTS with a horizontal shift factor that fits Arrhenius equation. Whereas TTS fails for SEBS-g-MA and the blends studied because of different temperature-sensitive response and microstructural changes of melt during shear application. © 2015 Springer-Verlag Berlin Heidelberg Source


Hamdani-Devarennes S.,Center Des Materiaux Of Grande Diffusion | Pommier A.,Center Des Materiaux Of Grande Diffusion | Longuet C.,Center Des Materiaux Of Grande Diffusion | Lopez-Cuesta J.-M.,Center Des Materiaux Of Grande Diffusion | Ganachaud F.,National Graduate School of Chemistry, Montpellier
Polymer Degradation and Stability | Year: 2011

The second part of this series, devoted to the study of model fire-resistant silicone composites filled with calcium or aluminium-based material which would meet cable industry specifications, focuses on residues obtained after extreme pyrolysis adapted from the NFC 32070 CR1 French standard. Several methods of analysis (among them ESEM, EDX, XRD, Hg pycnometer, and compression tests) have been carried out in order to investigate the microstructure, volume variation, and compression behaviour of silicone composite residues. Calcium-based fillers produced more cohesive residues than aluminium-based fillers. Indeed, the co-crystallisation taking place during pyrolysis, as shown in the first part of this series (Hamdani, S. et al., Polym Degrad Stab, 2010, 95, 1911-1919), produced a dense and strong residue. The strong internal porosity and absence of new crystal formation in residues of aluminium-based filled composites resulted in their low compressive resistance. In addition, water release during the degradation of the latter fillers, favoured residue expansion, high interior porosity and thus weak compression resistance. © 2011 Elsevier Ltd. All rights reserved. Source


Cinausero N.,Center Des Materiaux Of Grande Diffusion | Azema N.,Center Des Materiaux Of Grande Diffusion | Lopez-Cuesta J.-M.,Center Des Materiaux Of Grande Diffusion | Cochez M.,CNRS Laboratory of Optical Materials, Photonics, and Systems | Ferriol M.,CNRS Laboratory of Optical Materials, Photonics, and Systems
Polymer Degradation and Stability | Year: 2011

Synergism on fire properties has been investigated between nano-sized hydrophobic oxides (alumina and silica) and ammonium polyphosphate (AP) flame-retardant additive. Thermal degradation of mixed additives (50% w/w) showed the impact of oxides on AP degradation. The effect of modified nanoparticles was compared with corresponding hydrophilic oxide as regards thermal and fire behaviour. The nanocomposites prepared by melt-blending were evaluated by thermogravimetric analysis and cone calorimetry measurements. Residues were characterized by ATR-FTIR spectroscopy, X-ray diffraction and SEM-EDX experiments. A noteworthy decrease of peak of heat release rate and smoke opacity as well as an increase of LOI were noticed with hydrophobic silica combined with AP both in PMMA and PS. This flame-retardant behaviour was ascribed mainly to the formation of a specific silicon metaphosphate (SiP 2O7) crystalline phase which contributes to promote charring and an efficient insulating layer. © 2011 Elsevier Ltd. All rights reserved. Source


Bongono J.,Center Des Materiaux Of Grande Diffusion | Azema N.,Center Des Materiaux Of Grande Diffusion | Johannet A.,Center Des Materiaux Of Grande Diffusion | Gaudon P.,Center Des Materiaux Of Grande Diffusion
Powder Technology | Year: 2011

Measurement of characteristics of particles in suspensions without dilution has a practical interest in formulation, mineral processing, material sciences and environmental technologies.These characteristics are the size, shape, and surface properties of the primary particles, and also the size, structure and the number of primary particles in the agglomerates. In this work, the multiple light-scattering model through the optical analyzer, Turbiscan MA 2000 is used to determine the mean settling velocities of monodisperse glass beads and two polydisperse samples of powders, kaolin D and alumina, differing by their particle size distribution, their shape and their surface properties. Beyond the experimental validation of theoretical and empirical predictions, the nonlinear adjustment of experimental settling data gives the number of primary particles per agglomerate and the agglomerate size. These two characteristics lead to the determination of the fractal dimension of the agglomerates. The latter was found in the range of 2.5-2.7 for all suspensions examined. The calculation of permeability and spherical factor reveals the nonspherical impermeable agglomerates. © 2010. Source


Tibiletti L.,Center Des Materiaux Of Grande Diffusion | Tibiletti L.,Ashland Polyester SAS | Longuet C.,Center Des Materiaux Of Grande Diffusion | Ferry L.,Center Des Materiaux Of Grande Diffusion | And 4 more authors.
Polymer Degradation and Stability | Year: 2011

Nano-alumina and submicron alumina trihydrate particles were incorporated into an unsaturated polyester resin at various loadings. The morphologies of composites showed that only nano-alumina was correctly dispersed. The thermal degradation behaviour of the composites was studied using thermogravimetric analysis and Py-GC/MS, while their fire behaviour was investigated using cone calorimeter and pyrolysis combustion flow microcalorimeter. Synergistic effects on thermal stability and heat release rate were observed for combinations between both submicron filler and nanofiller. The best result for fire behaviour was obtained for a global loading of 10wt% with an equal mass ratio for both kind of particles. Mass loss curves also showed increased char yield. The interest of combining particles with different sizes has been discussed as well as the role of water release, regarding activations energies of degradation processes. © 2010 Elsevier Ltd. All rights reserved. Source

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