Mechanical properties of flame-retardant polypropylene compositions

The application of pentabromobenzyl acrylate monomer (PBB-MA) extrusion polymerized in ethylene-propylene-diene monomer (EPDM) terpolymer allows the production of flame-retardant polypropylene (PP) with very high impact and elongation at break and good resistance to thermal aging. The explanation of the high level of mechanical properties and of thermal aging resistance of PP/(EPDM/PBB-MA) is based on the hypothesis of EPDM/PBB-MA graft polymerization on EPDM double bonds, resulting in PP amorphization and in specific morphology: better dispersion of flame retardant (FR) in PP and in EPDM and the formation of a honeycomb structure of EPDM/PBB-MA particles. Addition of either EPDM/PBB-MA or EPDM+PBB-PA to glass-fiber-reinforced polypropylene (GFR PP) makes feasible the combining of two modes of PP toughening: via glass fiber reinforcement and via EPDM-based particle dispersion in PP matrix.