Synthesis and Characterization of Polyethylene Terephthalate–Derived Graphene Reinforced Hydroxyapatite–Kaolin Composites for Bone Tissue Engineering

Articles in Press

Document Type : Original Paper

Authors

1 Department of Industrial Chemistry, College of Science and Technology, Covenant University Ota Ogun State, Nigeria

2 FunGlass – Centre for Functional and Surface Functionalized Glass, Študentská 2, 911 50 Trenčín, Slovakia

10.22075/imcf.2025.39269.1048

Abstract

This study presents the synthesis and physicochemical characterization of a graphene–hydroxyapatite–kaolin (GHK) composite designed for potential artificial bone applications. Graphene was derived from recycled polyethylene terephthalate (PET) waste through pyrolysis at 600 °C, while hydroxyapatite (HAp) was synthesized from calcined eggshells and combined with kaolin clay. The powders were compacted and sintered at 1100 °C to produce three formulations. Porosity and density values were 22.5% and 2.75 g/cm³ for GHK-A, 19.8% and 2.85 g/cm³ for GHK-B, and 26.3% and 2.62 g/cm³ for GHK-C within the ASTM C373 standard range (porosity: 0–30%, density: 2.4–3.0 g/cm³). GHK-B exhibited the lowest porosity and highest density, indicating compactness and mechanical strength suitable for load-bearing bone applications. Fourier-transform infrared spectroscopy (FTIR) confirmed bands of PO₄³⁻ at 1030–960 cm⁻¹, OH⁻ stretching at 3570 cm⁻¹, and Si–O vibrations near 1100 cm⁻¹, validating the successful integration of HAp, kaolin, and graphene phases. X-ray diffraction (XRD) patterns showed distinct crystalline peaks corresponding to HAp planes at 2θ = 25.9°, 31.8°, and 39.9°, with GHK-B exhibiting sharper peaks than GHK-A and GHK-C, indicating improved crystallinity and phase purity. Scanning electron microscopy (SEM) revealed an interconnected porous network with flake-like graphene layers reinforcing the HAp-kaolin matrix suitable for osteoblast infiltration and nutrient transport. The synergy between graphene’s conductivity, HAp’s bioactivity, and kaolin reinforcement produced a composite with balanced structural properties. GHK-B demonstrated the most promising material combining cortical bone-like density (2.85 g/cm³), controlled porosity (19.8%), and superior crystalline structure suggesting its potential as a mechanically bioactive scaffold for bone tissue regeneration.

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Innovations in Materials: Current & Future

Articles in Press, Accepted Manuscript
Available Online from 08 December 2025

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History

  • Receive Date: 04 October 2025
  • Revise Date: 27 October 2025
  • Accept Date: 26 November 2025
  • First Publish Date: 08 December 2025
  • Publish Date: 08 December 2025

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