Center Des Materiaux Of Lecole Des Mines Dales

Saint-Christol-lès-Alès, France

Center Des Materiaux Of Lecole Des Mines Dales

Saint-Christol-lès-Alès, France
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Tramaux A.,Center Des Materiaux Of Lecole Des Mines Dales | Azema N.,Center Des Materiaux Of Lecole Des Mines Dales | David G.,Charles Gerhardt Institute | Negrell C.,Charles Gerhardt Institute | And 3 more authors.
EPJ Web of Conferences | Year: 2017

Superplasticizers are chemical admixtures used to fluidize cement pastes. Among them, polycarboxylate are comb-like copolymers with carboxylic acid and poly(ethylene glycol) side chains. We present here the synthesis of various polycarboxylate-like copolymers including phosphonic acid functions. Their adsorption, dispersion and fluidification efficiencies are evaluated on calcium carbonate suspensions, a mineral material commonly used to simulate early-age cement behaviour. © The Authors, published by EDP Sciences, 2017.


Courtat J.,University Claude Bernard Lyon 1 | Melis F.,University Claude Bernard Lyon 1 | Taulemesse J.-M.,Center Des Materiaux Of Lecole Des Mines Dales | Bounor-Legare V.,University Claude Bernard Lyon 1 | And 3 more authors.
Polymer Degradation and Stability | Year: 2015

Abstract Surface modification of various silicas by phosphorous agents was carried out with the aim to use these particles as flame retardant additive in a polypropylene matrice (PP) at low content (10 wt%). Thermal and flammability properties of PP/modified silica (PP-Tm-10%, PP-Zm-10%) were studied using TGA, PCFC and cone calorimeter and compared to those conferred by pure silica (PP-T-10%, PP-Z-10%). Quite surprisingly the untreated fillers induce the most significant reduction of peak of Heat Release Rate (50% decrease) while the surface modification by phosphorous agents does not lead to the expected effect on the fire behavior of PP composite. This phenomenon was related to the morphology and rheological behavior of the various PP composites. Indeed, the higher the storage modulus at low frequencies is, the better the fire behavior is, because of the induced barrier effect. Moreover, the addition of non modified silicas leads to a decrease of 10 s of the TTI. This phenomenon was related to the formation of bubbles after the PP melting during cone calorimeter test. © 2015 Elsevier Ltd.


Puerta-Falla G.,University of California at Los Angeles | Balonis M.,University of California at Los Angeles | Le Saout G.,Center Des Materiaux Of Lecole Des Mines Dales | Kumar A.,University of California at Los Angeles | And 4 more authors.
Journal of Materials Science | Year: 2016

The addition of slightly (CaCO3) and highly soluble (Na2CO3) carbonate salts is expected to favor the formation of carboaluminate phases in hydrated calcium aluminate cements (CACs). A multi-method approach including X-ray diffraction, thermogravimetric analysis, and thermodynamic calculations is applied to highlight that the “conversion phenomena” in CACs cannot be mitigated by the formation of carboaluminate phases (monocarboaluminate: Mc and hemicarboaluminate: Hc) which are anticipated to form following the addition of carbonate salts. Here, carboaluminate phase formation is shown to depend on three factors: (1) water availability, (2) carbonate content of the salts, and their ability to mobilize CO3 2− species in solution, and (3) lime content associated with the carbonate salt. The latter two factors are linked to the composition and solubility of the carbonate agent. It is concluded that limestone (CaCO3), despite being a source of calcium and carbonate species, contributes only slightly to carboaluminate phase formation due to its low solubility and slow dissolution rate. Soluble carbonate salts (Na2CO3) fail to boost carboaluminate phase formation as the availability of Ca2+ ions and water are limiting. Detailed thermodynamic calculations are used to elucidate conditions that affect the formation of carboaluminate phases. © 2016 Springer Science+Business Media New York


Autier C.,Center Des Materiaux Of Lecole Des Mines Dales | Azema N.,Center Des Materiaux Of Lecole Des Mines Dales | Taulemesse J.-M.,Center Des Materiaux Of Lecole Des Mines Dales | Clerc L.,Center Des Materiaux Of Lecole Des Mines Dales
Powder Technology | Year: 2013

One of the parameters that condition the workability of concrete is the dispersion state of cement paste. Water trapped into the agglomerates does not contribute to flow properties and fine particles forming agglomerates are not available for packing optimization. Therefore, superplasticizers have been developed to disperse particles, thus increasing the flowability of the material for the same water/cement ratio. Using the complementarity between scanning electron microscopy (SEM) and laser granulometry, dispersion states of cement pastes were characterized. The different kinds of particles and their meso-structural organization were identified, along with transfers of particles that can occur between the different granulometric classes. For that purpose, several liquid media were used for the analysis and different superplasticizers were incorporated for the mixing. Dispersion indices were developed and compared with the flow behavior of pastes. This comparison underlines the link between mesoscopic state and rheological behavior. This multi-scale approach of experimental characterization may be easily applied to other studies characterizing the influence of surfactants on dispersion phenomena in several fundamental and industrial areas. © 2013.


Sonnier R.,Center Des Materiaux Of Lecole Des Mines Dales | Bokobza L.,Center Des Materiaux Of Lecole Des Mines Dales | Concha-Lozano N.,Center Des Materiaux Of Lecole Des Mines Dales
Polymers for Advanced Technologies | Year: 2015

Poly(dimethylsiloxane) (PDMS) filled with low contents of multiwall carbon nanotubes (MWCNT) was prepared using different ways to monitor the dispersion of MWCNT. The influence of the dispersion on thermal conductivity and transmittance was measured. High degree of transparence can be achieved with 0.02 phr of well dispersed MWCNT. Time-to-ignition (TTI) was also measured on 2- or 4-mm-thick specimens heated using radiative unidirectional source. Time-to-ignition was found to decrease with the incorporation of MWCNT because more heat is absorbed at the surface. Higher time-to-ignition was observed for partially translucent composites, due to different absorption in-depth profiles. It can be assumed that time-to-ignition can be controlled by the dispersion of MWCNT into the polymeric matrix. © 2015 John Wiley & Sons, Ltd.


Sonnier R.,Center Des Materiaux Of Lecole Des Mines Dales | Viretto A.,Center Des Materiaux Of Lecole Des Mines Dales | Dumazert L.,Center Des Materiaux Of Lecole Des Mines Dales | Gallard B.,Center Des Materiaux Of Lecole Des Mines Dales
Combustion and Flame | Year: 2016

A method to distinguish the mass loss rates corresponding to each of the two decomposition steps in binary blends is proposed. This method is suitable for cone calorimeter test and all other tests measuring continuously mass loss and heat release in an independent way. Heat release rate curves recalculated from the method well fit the experimental ones. Several systems including copolymers, polymers filled with inert or hydrated fillers and binary blends were studied. It appears that the decomposition of these materials is complex because the decomposition rate of one component influences the decomposition rate of the second one. These interactions depend on the materials, their content and also the external heat flux. Concerning binary blends, first results show the decomposition of the most thermally stable polymer is delayed because the temperature within the material is maintained close to the pyrolysis temperature of the least thermally stable polymer. Longer is the delay, higher is the decomposition rate of the most thermally stable polymer. In some cases, this polymer can decompose at higher rate (but later) than the least stable polymer. © 2016 The Combustion Institute.


Viretto A.,Center Des Materiaux Of Lecole Des Mines Dales | Sonnier R.,Center Des Materiaux Of Lecole Des Mines Dales | Taguet A.,Center Des Materiaux Of Lecole Des Mines Dales | Otazaghine B.,Center Des Materiaux Of Lecole Des Mines Dales | And 3 more authors.
Fire and Materials | Year: 2016

Magnesium dihydroxide (MDH) was evaluated as char promoter into different polymers exhibiting various chemical structures. Char promotion was characterized using thermogravimetric analysis and pyrolysis-combustion flow calorimetry. Gases released during pyrolysis were identified using pyrolysis coupled gas chromatography/mass spectrometry and thermogravimetric analysis coupled Fourier transform infrared spectroscopy. Relationships between the MDH effect (according to the char content and its thermal stability) and the chemical structure of the host polymers were identified. It was shown that MDH can be a good char promoter for aromatic polyesters such as polybutylene terephtalate and polyethylene terephtalate. Char promotion can be considered as one of the main mode-of-action of MDH at low or moderate filler content. An optimum was observed at approximately 20wt.% of MDH. Magnesium oxide was also studied as substitute to MDH to avoid hydrolysis phenomena due to the water release. But it was demonstrated that MDH was more efficient as a char promoter for polybutylene terephtalate than magnesium oxide. © Copyright 2015 John Wiley & Sons, Ltd.


Sonnier R.,Center Des Materiaux Of Lecole Des Mines Dales | Caro-Bretelle A.-S.,Center Des Materiaux Of Lecole Des Mines Dales | Dumazert L.,Center Des Materiaux Of Lecole Des Mines Dales | Longerey M.,Center Des Materiaux Of Lecole Des Mines Dales | Otazaghine B.,Center Des Materiaux Of Lecole Des Mines Dales
Radiation Physics and Chemistry | Year: 2015

Fire behavior of flame retardant-free and flame retarded PP/PA6 blends was studied using pyrolysis-combustion flow calorimeter, cone calorimeter and epiradiator equipped with infrared camera and pyrometer. Blends were previously γ-irradiated in presence of crosslinking agents at various doses (up to 100. kGy) in order to assess the influence of irradiation crosslinking on flame retardancy. Crosslinked specimens exhibit a solid-like behavior under high temperature gradient in cone calorimeter and then distort considerably. The influence of such a behavior depends on the material properties. When the flame retardancy is provided by heat shielding effect, heat distortion disrupts the top protective layer leading to a substantial increase of peak of heat release rate (pHRR). The barrier layer is no longer able to prevent the heat transfer to the underlying condensed phase. In other cases (flame retardant-free blends or flame retardancy provided by other effects than heat shielding), heat distortion has negligible influence on heat release rate curves in cone calorimeter tests. © 2014 Elsevier Ltd.

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