Mechanical properties of recycled polypropylene composites with walnut shell additives by injection moulding

Year 2025, Issue: 063, 101 - 108, 30.12.2025

Ömer Şengül

https://doi.org/10.59313/jsr-a.1757449

Abstract

In this study, recycled polypropylene, which is one of the commonly used thermoplastics, and walnut shell powders were used as fillers. To increase the compatibility of the composite material, 3% SiO₂ particle size of 75 nm was added. In this research, a new composite material was produced by minimizing the harmful effects of the composite material on the environment. Some mechanical properties of this new material were investigated. Walnut shell powder was added to recycled Polypropylene (PP) material at the rates of 2, 5, 8, 10, 12.5, 15, 18, and 20%. The regenerated polypropylene matrix was modified with walnut shell–derived natural reinforcement, leading to a composite material exhibiting enhanced mechanical performance. Tensile test, density test, hardness test and Izod impact tests were applied to the new composite material. As a result of the tests, 15% Walnut Shell Powder (WSP) was found to be the most suitable filler. In the new composite material, 10% improvement in tensile strength, 11% improvement in yield strength and 106% improvement in modulus of elasticity occurred. As a result of the Izod impact test, 11% improvement occurred. The hardness and density value of the new composite material increased by 4 and 11%, respectively. The study verifies that the application of walnut shells as a natural filler considerably strengthens the environmental and performance-related benefits of recycled polypropylene composites. This study shows that when walnut shells are used as fillers, it enables recycled polypropylene composite to be much more advantageous as filler in terms of both environmental sustainability and performance.

Keywords

Recycling , polypropylene , walnut shell , composites , mechanical properties , mechanical tests

Ethical Statement

This research involves only material testing and analysis. No human or animal subjects were used, and no ethical approval was necessary.

Supporting Institution

There is no supporting institution.

Thanks

I would like to thank the journal editorial board.

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