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Lignin was used as flame retardant for polybutylene succinate (PBS) biopolyester. Lignin was first demonstrated to weakly contribute to material flammability due to a high charring ability and a low heat release when burning. Alkali lignin was proved to be more interesting than organosolv lignin due to the release of sulfur dioxide during decomposition. When incorporated at a 20%wt loading in PBS, alkali lignin significantly reduces pHRR and promotes a thick charring behavior. Alkali lignin was successfully surface modified by grafting molecular or macromolecular phosphorous compounds. When blended with PBS, modified lignin was highlighted to further increase the barrier effect. Char promotion is accelerated and the resulting charred layer exhibits a higher cohesivity. Modified lignin appears as an interesting biobased flame retardant component. [ABSTRACT FROM AUTHOR]

The flammability of various flame-retarded formulations containing different hydrated mineral fillers and/or phosphorous compounds and/or carbon nanotubes has been investigated using both a cone calorimeter and a pyrolysis combustion flow calorimeter (PCFC). A method was proposed to evaluate the barrier effect of the flame-retardant additives. This method is based on the fact that the PCFC is non-sensitive to physical flame-retardant effects whereas both chemical and physical phenomena have a great effect on cone calorimeter results. Therefore, normalized peak of heat release rate (pHRR) values obtained with both techniques do not always show a good correlation. It was highlighted that the mismatch between both pHRR results was related to the formation of a protective layer during combustion. Protective layers have been evidenced independently by visual observations. Thus, it is proposed that the magnitude of the deviation from a perfect correlation between cone calorimeter and PCFC pHRRs could be used to quantify the magnitude of barrier effect. Although the results obtained from different fire tests are generally not correlated, such an approach based on the complementarity of different techniques appears more relevant despite of its empirical nature. Copyright © 2011 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Abstract: Transparent polycarbonate nanocomposites with improved fire behavior were prepared by incorporation of polyhedral oligomeric silsesquioxane (POSS) and resorcinol bis (diphenyl phosphate) (RDP) via melt blending. Flame retardancy performance was characterized using thermogravimetric analysis, pyrolysis combustion flow calorimeter and cone calorimeter. Simultaneous presence of RDP and POSS led to the decrease of the degradation rate and the increase of char residue due to the reaction of the additives with the decomposing polymer. This results in a significant reduction of flammability of polycarbonate. In cone calorimeter, the heat release rate as well as the smoke production rate were shown to strongly decrease due to a condensed phase mechanism that favored the formation of a cohesive char layer. Transparency evaluation was performed in both physical and psychophysical spaces. The two approaches give various assessment of transparency. Considering the perceived optical properties, it could be concluded that flame retarded PC is translucent rather than transparent. [Copyright &y& Elsevier]

Expanded polystyrene (EPS) foam has been successfully flame retarded by a water-based coating containing nanoparticles of boehmite and poly(vinyl alcohol) (PVOH) as char former. Boehmite enhances the charring of PVOH. The influence of suspension viscosity, coatings number, impregnation time and drying method was studied to monitor the amount of coating deposited and the coating thickness. The coating suspension is able to penetrate into the core of the foam. EPS without hexabromocyclododecane (HBCD) is upgraded from F to E rating according to the NF EN ISO 11925-2 standard when the penetration of coating suspension into the core is high enough, due to the formation of a char layer reinforced by nano-boehmites even if EPS does not shrink away from the flame. [ABSTRACT FROM AUTHOR]

Abstract: Modified kaolinite poly(methyl methacrylate) nanocomposites were prepared using successively in situ polymerization and melt blending methods. Pristine kaolinite (Kaol) was intercalated using two organic molecules dimethyl sulfoxide (DMSO) and dodecylamine. This treated kaolinite (TKaol) was exfoliated via in situ polymerization of MMA. The prepared blends were extruded with a commercially available PMMA and then injection molded. The thermal degradation and flammability of TKaol PMMA nanocomposites was compared to pure PMMA and also to PMMA nanocomposites filled with untreated Kaol. Results showed the influence of Kaol morphology on fire behavior of these nanocomposites. The use of exfoliated Kaol allowed a better thermal stability to be achieved and the decrease of peak heat release rate (PHRR) as revealed by the cone calorimeter tests. Moreover, TKaol PMMA nanocomposite enabled to maintain time to ignition close to that of PMMA while it was largely reduced with PMMA nanocomposites filled with untreated Kaol. Finally, exfoliated Kaol led to an efficient barrier effect due to the formation of a cohesive residue as highlighted by its mechanical strength. [Copyright &y& Elsevier]