Flame Retardant <scp>PP</scp> Bio Composites Filled With <scp>ATH</scp> and Reinforced With Surface Modified Sisal Fiber (<scp>SF</scp>): Investigation of the Mechanical, Thermal, Morphological and Flammability Properties of Thermoplastic Polymer <sc

ABSTRACT The current study focuses on the development of flame‐retardant bio‐composites based on polypropylene (PP) reinforced with surface‐modified sisal fibers (SF) and filled with aluminum trihydrate (ATH). An in‐depth study on the mechanical, thermal, morphological, and flammability properties of the PP/ATH bio‐composites has been undertaken. Experimental findings revealed that incorporation of 30 wt% of surface modified SF and 3 wt% of ATH has led to a 57% increase in tensile strength and a 176% increase in impact strength as compared with neat PP. Differential scanning calorimetry (DSC) analysis showed higher crystallinity in the bio‐composites due to the nucleating effects of ATH, restricting the mobility of the matrix polymer chains. Thermogravimetric analysis (TGA) revealed improved thermal stability in the bio‐composites, and an increase in final degradation temperature. Scanning electron microscopy (SEM) analysis confirmed uniform fiber dispersion and strong fiber‐matrix bonding. Flammability tests in the bio‐composites employing UL‐94 showed a V‐2 rating with nearly a 29% decreased rate of burning. Limiting oxygen index (LOI) studies showed an increase from 18% (neat PP) to 24%, in the case of the bio‐composites with a decreased PHRR to the tune of 22%. These results demonstrate the synergistic effect of ATH and modified SF in enhancing fire resistance while maintaining mechanical integrity in the PP/ATH/SF bio‐composites.