Sustainable Composites from Recycled Polypropylene and Hazelnut Shell Flour for Application in Irrigation Systems

Area of Science:

• Materials Science
• Polymer Engineering
• Sustainable Manufacturing

Background:

• The irrigation sector requires eco-sustainable materials to replace traditional fittings made from virgin fossil-based polymers.
• Developing high-performance, environmentally friendly alternatives is crucial for reducing plastic waste and promoting a circular economy.

Purpose of the Study:

• To develop sustainable composites using recycled polypropylene (RPP) and hazelnut shell (HS) powder.
• To evaluate the rheological and mechanical properties of these composites for irrigation fitting applications.
• To assess the effectiveness of maleic-anhydride-grafted polypropylene (PPC) as a coupling agent.

Main Methods:

• Melt-compounding of RPP with HS powder, with and without PPC coupling agent.
• Rheological characterization to assess processability at high shear rates.
• Tensile testing to determine mechanical properties like elastic modulus and elongation at break.
• Injection molding of composite samples (sleeve bodies and nuts) and pressure testing up to 3.5 bar.

Main Results:

• Composite viscosity curves converged with matrices at high shear rates, indicating negligible differences in processability.
• Adding 10 wt% HS powder increased elastic modulus by ~30% but reduced elongation at break by ~90% in RPP.
• PPC coupling agent mitigated ductility loss, increasing elongation at break from 6% to 18% in RPP-based composites.
• Injection-molded parts resisted internal water pressure up to 3.5 bar without failure.

Conclusions:

• Agro-industrial waste (HS powder) can be effectively valorized as a functional filler in RPP.
• Composites demonstrate comparable mechanical and processing performance to virgin polypropylene for irrigation fittings.
• This research supports the transition to a circular economy by enabling sustainable material solutions.