Reinforcement Effect of Nanosilica on the Mechanical and Thermal Performance of Pine Wood Flour/Recycled Polypropylene Hybrid Composites

Document Type : Original Article

Authors
Jafar Ebrahimpour-Kasmani 1
Ahmad Samariha 2
1 Associate professor, Department of Wood and Paper, Sava.C., Islamic Azad University, Savadkooh, Iran
2 1. Associate professor, Department of Wood and Paper, Sava.C., Islamic Azad University, Savadkooh, Iran 2. Assistant professor, Department of Engineering Sciences, Technical and Vocational University (TVU), Tehran, Iran
10.22034/stme.2025.543980.1163
Abstract
This study examines the influence of nanosilica incorporation on the mechanical and thermal performance of hybrid biocomposites composed of pine wood flour and recycled polypropylene. Composite formulations containing 50 wt% polypropylene, 50 wt% pine wood flour, nanosilica at four loadings (0, 3, 6, and 9 wt%), and 3 wt% maleic anhydride grafted polypropylene were compounded using a twin-screw extruder. Standardized test specimens were subsequently manufactured by injection molding. Mechanical properties—tensile and flexural strength and modulus, as well as notched Izod impact strength —alongside thermal behavior and flammability characteristics were evaluated. Increasing nanosilica content to 9 wt% resulted in reductions of 12.98% and 5.16% in tensile strength and tensile modulus, respectively. Flexural strength, flexural modulus, and notched impact strength also declined by 6.1%, 5.02%, and 10.92%, respectively. Conversely, the limiting oxygen index exhibited a 12.4% increase at the highest nanosilica loading, accompanied by higher residual char and improved thermal stability. Morphological analyses further showed fewer interfacial voids in specimens containing 3 wt% nanosilica, indicating superior fiber–matrix adhesion and reduced fiber pullout. Overall, nanosilica demonstrated a favorable contribution to the thermal performance of the composites, though excessive loading adversely affected mechanical properties due to nanoparticle agglomeration. The findings highlight the importance of optimizing nanosilica content to achieve a balanced enhancement of mechanical and thermal functionalities in bio-based polymer composites.
Keywords
Pine wood flour؛ recycled polypropylene؛ flexural strength؛ flexural modulus؛ nanosilica
Residual Char
Subjects

اصل مقاله

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Science and Technology in Mechanical Engineering
Volume 4, Issue 2 - Serial Number 7
February 2026
Pages 241-255

  • Receive Date 29 August 2025
  • Revise Date 02 November 2025
  • Accept Date 22 November 2025
  • First Publish Date 22 November 2025
  • Publish Date 21 January 2026