Flame retardant treatments of insulating agro-materials from flax short fibres

Improving fire resistance of lignocellulosic agro-materials is essential to extend their application domain. In this study, flame retardant agents, among which aluminium tri-hydroxide (ATH), zinc borate (ZB), melamine phosphate (MMP) and melamine borate (MMB), were incorporated in insulating materials based on flax short fibres. All flame retardant fillers were fixed firmly and permanently on the flax fibres using a protein binder. The incorporation was also homogeneous and preserved materials open porosity and expanded structure.Flame retardancy was characterized by Mass Loss cone calorimetry and UL 94 horizontal burning test. Materials morphology and thermal degradation were also investigated by scanning electron microscopy (SEM) and thermo-gravimetric analysis (TGA). Among all tested flame retardants, the best results were obtained with MMB. Immediate flame extinction was already achieved at 10 wt% loading rate, whereas the ignition time increased up to 6 times at 30 wt%, compared to the reference.