Desenvolvimento de compósitos retardantes de chama de polipropileno e lignosulfonato modificado com zircônio

Abstract

Conventional flame retardant composites are generally made with toxic chemicals that can release hazardous gases when burned, such as halogenated compounds. In contrast, flame retardant additives from renewable sources are capable of effectively resisting flames, making them a safer and more sustainable alternative. Materials based on polypropylene (PP) and sodium lignosulfonate (LG) were synthesized with zirconium oxide and phosphate (ZrO2, ZrP), and the additives ammonium phosphate (AP), ammonium polyphosphate (APP), and sulfonol (SULF) were evaluated as potential flame retardants in polymeric materials. The contents of the additives that showed the best results were then modified, and the modified lignosulfonate (LGMod), obtained through the magnetron sputtering technique, was incorporated. The materials were processed in a torque rheometer followed by compression molding. The synthesized samples were characterized by Field Emission Scanning Electron Microscopy (FEG-SEM), Thermogravimetric Analysis (TGA), Thermal Camera, UL-94 Vertical Burn Test, as well as their mechanical properties evaluated. The LGMod was investigated by EDS, where the incorporation of zirconium into the lignosulfonate was confirmed. The presence of the additives in the polypropylene matrix was proven by SEM. Through TGA, it was analyzed that the materials with lower combustion and ignition indices also performed better in the vertical burn test. It is noteworthy that the PP/18AP, PP/25AP, PP/25AP/3LG/5ZrP, PP/25AP/8LGMod, and PP/15SULF/8LG/5ZrO2 composites achieved V2 classification in the UL-94 test. As analyzed by the thermal camera, PP/25AP showed a smaller temperature variation and rapid flame extinction, with a mass loss of 3.27% after burning. Furthermore, LGMod contributed to self-extinguishing the flames approximately 78% faster than ZrP. In terms of mechanical properties, the composites showed lower impact and flexural strength compared to pure polypropylene but presented a higher flexural modulus and elasticity. [resumo fornecido pelo autor]