Investigation of glass-fiber reinforced polypropylene properties dependence on post-consumer recycled polypropylene content

Polymer composites like glass fiber-reinforced polypropylene (GFRP) are widely used for their strength and lightweight properties, but their limited recyclability has raised significant sustainability challenges. This study explores the potential to improve the sustainability of GFRP composites by adding post-consumer recycled polypropylene (rPP). The impact of rPP and specifically of titanium dioxide (TiO₂), found in rPP as a residue of white inks, is evaluated. Two material sets were analyzed: one with varying rPP percentages and one with different TiO₂ levels intentionally added to virgin PP. Mechanical and rheological properties were evaluated through tensile and impact strength, DSC, TGA, SEM, and fiber length measurements. Results revealed TiO₂ contamination reduces fiber length, contributing to mechanical performance degradation. The findings highlight TiO₂’s significant role in recycled GFRP performance and emphasize improving recycling processes to enhance sustainability.