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International audience

A new halogen‐free flame retardant was developed by integrating β‐cyclodextrin, triazin ring, and nanohydroxyapatite (BSDH) into a hybrid system. A β‐cyclodextrin was grafted to a commercially available SABO®STAB UV94 via an aromatic deanhydrate. The BSDH was prepared in situ in the presence of β‐cyclodextrin‐grafted nitrogen‐rich precursor. The resulting hybrid was applied as a flame retardant for poly(lactic acid) (PLA) and compared for performance with ammonium polyphosphate (APP). PLA composites containing BSDH and APP, individually or simultaneously, were examined for thermal degradation and flammability by TGA, cone calorimeter, and pyrolysis‐combustion flow calorimetry. TGA results confirmed enhancement of thermal stability of PLA with assistance of BSDH compared to APP. The gases evolved during thermal degradation were assessed by a thermogravimetric analysis and Fourier infrared spectroscopy device. APP revealed catalytic effect to initiate PLA degradation, while BSDH continued to release some gases at elevated temperatures. The flame retardancy of PLA/APP/BSDH blend containing only 10 wt.% of additives was significantly improved. In cone calorimetric tests, a significant fall in peak of heat release rate was observed for this sample, 49% more than that of neat PLA, which was indicative of more gas and condensed phase reflected in more char residue. The corresponding PLA/APP sample, however, showed 17% improvement, as compared to neat PLA. Also, total heat release rate of PLA/APP/BSDH was 45 MJ.m−2, whereas those of PLA and PLA/APP were 89 and 65 MJ.m−2, respectively. BSDH and APP showed a synergistic effect on improving the flame retardancy of PLA composites.

International audience

Fiber-reinforced thermoplastic composite materials can find numerous applications in the transportation sector and replace thermoset composites. However, they have to comply with strict standards, particularly with those concerning their fire behavior. In this frame, composites based on an acrylic resin Elium ® (Arkema), a woven fiberglass, (taffetas tissue Chomarat G-Weave 600 P/A) and Exolit OP930 (Clariant) as fire retardant were prepared using three processes. The thermal stability and fire behavior was studied by means of thermogravimetric analysis and cone calorimetry. The obtained results allowed to highlight the drawbacks of each processing method and to select the most appropriate. The improvement of the fire behavior by combining post-curing of the composites, addition of a cross-linking agent and addition of aluminum trihydroxide (ATH) was also investigated.

This work aims to investigate the fire retardant properties of a novel type of high-density polyethylene composites. Our intumescent system consists in using classical flame retardants such as ammonium polyphosphate, pentaerythritol in combination with porous mesostructured silica (SBA-15) fillers. Prior to use, SBA-15 was chemically modified using different organic and inorganic grafts in order to obtain some specific properties, such as an improved compatibility with the polymer, or different types of surface acidity in order to increase charring reactions. Limiting oxygen index, UL-94, pyrolysis flow combustion calorimetry and thermogravimetric analysis were used to assess the burning behavior and thermal stability, respectively, of the processed composites. By keeping the total amount of additives always equal to 25wt%, the better flammability characteristics were in general obtained at low SBA-15 loadings (