Enhancing properties and manufacturability of post-consumer recycled polypropylene via gas counter-pressure injection molding

In contemporary times, the most effective strategy to mitigate the environmental effects of plastics and their manufacturing is through recycling. Nonetheless, the production of high-quality items from recycled materials remains a challenge. This study addresses these challenges, specifically in the context of the injection molding process for recycled polypropylene. The key issues identified include poor surface finish of the molded items, mold contamination with oily residues, and strong odors during processing. The proposed solution involves the innovative use of gas counter pressure in conjunction with injection molding. The study explores various nitrogen pressure levels to assess their impact. Findings indicate that an optimal pressure level significantly improves the surface quality of the products and reduces the accumulation of dirt in the mold cavities. Additionally, the research investigates the potential impact of this method on the mechanical performance of the molded items. Results confirm that the appropriate use of gas pressure does not deteriorate these properties. While gas counter pressure does not mitigate odor emissions, it represents a promising step forward in developing a highquality recycled polypropylene compound. This approach could pave the way for more advanced recycling techniques, enhancing the quality of products made from recycled plastics.