Through a straightforward approach, a new meltable, halogen-free, nitrogen-phosphorus-based flame retardant (FR), 6-(2-(4,6-diamino-1,3,5-triazin-2-yl)ethyl) dibenzo [c,e][1,2]oxaphosphinine 6-oxide (DTE-DOPO) was synthesized and incorporated in polyamide 6 (PA6).It was proved that a very low phosphorus content of 1.46 wt % for DTE-DOPO additive improved the flame retardancy of PA6, leading to a non-flammable material. The performance of the new additive was compared to that of the commercially-available Exolit OP 1230. The PA6 formulations were evaluated by measuring the rheological, mechanical, and flammability behavior. Using compounding by melt extrusion, 17 wt % additives was introduced into PA6 matrix and the corresponding formulations were characterized. The results evidenced a higher homogeneity of DTE-DOPO with PA6, a high thermal stability with a catalyzing decomposition effect on PA6 caused by the presence of the new developed FR, enhanced elasticity for the PA6/DTE-DOPO formulation and a V0 rating for both formulations. Thermal and fire analysis indicated a primary gas-phase activity, combined with a complete suppression of the self-sustained burning for the PA6/DTE-DOPO formulation.Polymers 2015, 7 1542

A novel group of silsesquioxane derivatives, which are siloxane-silsesquioxane resins (S4SQ), was for the first time examined as possible flame retardants in polypropylene (PP) materials. Thermal stability of the PP/S4SQ composites compared to the S4SQ resins and neat PP was estimated using thermogravimetric (TG) analysis under nitrogen and in air atmosphere. The effects of the non-functionalized and n-alkyl-functionalized siloxane-silsesquioxane resins on thermostability and flame retardancy of PP materials were also evaluated by thermogravimetry-Fourier transform infrared spectrometry (TG-FTIR) and by cone calorimeter tests. The results revealed that the functionalized S4SQ resins may form a continuous ceramic layer on the material surface during its combustion, which improves both thermal stability and flame retardancy of the PP materials. This beneficial effect was observed especially when small amounts of the S4SQ fillers were applied. The performed analyses allowed us to propose a possible mechanism for the degradation of the siloxane-silsesquioxane resins, as well as to explain their possible role during the combustion of the PP/S4SQ composites.

This study investigates the possible enhancement of flame resistance in powder-epoxy resin/glass fabric composites. For this purpose, the halogen-free flame retardants containing phosphorous, nitrogen and aluminium were used. The total content of the fillers did not exceed 25 wt%. The laminates assessed for flame retardancy were designed specifically to be used as components of seats in public transport. Thermal resistance of the laminates and the surfaces of partially burned composites were also examined using thermogravimetric and scanning electron microscopy/energy-dispersive x-ray spectroscopy analyses, respectively. On the basis of the obtained results, it was found that the highest flame resistance (V-0 class, minimum oxygen concentration = 35.5% and maximum average rate of heat emission = 38.5 kW/m2 at an incident heat flux of 50 kW/m2) was identified in the laminates with matrix comprising 15 wt% aluminium diethyl phosphinate and 10 wt% melamine polyphosphate. In turn, the laminates with the matrix containing ammonium polyphosphate as the main component achieved only the V-1 flammability class.

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