Silver streaks dependence on processing conditions in the injection molding of post-consumer recycled polypropylene

The growing emphasis on sustainability in plastic waste management has driven interest in recycled polymers, including post-consumer recycled polypropylene. A critical challenge in this field is achieving satisfying aesthetic surface quality in molded components, particularly when defects such as silver streaks arise. This study explores the influence of injection molding processing parameters on the physical and chemical mechanisms underlying defect formation, with a focus on the role of volatile organic compounds released from the degradation of residual inks and binders. Results reveal that silver streaks are significantly influenced by melt temperature, shear rates, and injection speed. These findings not only improve our understanding of how silver streaks form but also suggest practical ways to improve the quality of recycled polypropylene products by adjusting process parameters.