Processing and Mechanical Properties of Highly Filled PP/GTR Compounds.

Area of Science:

• Materials Science
• Polymer Chemistry
• Recycling Technology

Background:

• Ground tire rubber (GTR) is challenging to recycle due to its cross-linked structure, limiting its thermoplastic applications.
• Developing effective recycling methods for GTR is crucial for sustainability and resource management.

Purpose of the Study:

• To investigate the injection moldability of highly filled polypropylene/ground tire rubber (PP/GTR) compounds.
• To evaluate the impact of a specific peroxide modifier, 2.5-dimethyl-2.5-di-(tert-butylperoxy)-hexane, on PP/GTR processing and properties.
• To determine the optimal GTR content for effective processing and property enhancement.

Main Methods:

• Injection molding of PP/GTR compounds with varying GTR content (30-90 wt.%) and a peroxide modifier.
• Melt flow index (MFI) testing to assess rheological properties.
• In-mold temperature and pressure monitoring during injection molding.
• Mechanical testing including hardness, impact, and static tensile tests.
• Differential scanning calorimetry (DSC) for thermal property analysis.

Main Results:

• Efficient injection molding of PP/GTR compounds with up to 90 wt.% GTR was achieved.
• The peroxide modifier improved the rheological properties of the PP matrix, enhancing GTR-matrix bonding.
• Reduced cooling times in the injection mold were observed, leading to shorter production cycle times.
• Mechanical properties, such as hardness and tensile strength, were improved due to better filler-matrix adhesion.

Conclusions:

• Injection molding is a viable method for processing highly filled PP/GTR compounds.
• The addition of 2.5-dimethyl-2.5-di-(tert-butylperoxy)-hexane significantly enhances the processability and mechanical performance of PP/GTR composites.
• This research offers a promising pathway for the effective recycling and utilization of ground tire rubber in polymer applications.