The primary purpose of this study is to develop an eco-sustainable and high-performance three-dimensional (3D)-printed polymer composite by reinforcing polyethylene terephthalate glycol (PETG) with short bamboo fibre (SBF) and nano-scale coconut shell ash (CSA-n). The study aims to enhance the mechanical, structural and interfacial characteristics of PETG through a hybrid reinforcement strategy that uses renewable natural fibres and waste-derived nano-fillers. By integrating SBF for strength and nano-scale CSA for improved interfacial bonding and thermal stability, the work seeks to address the limitations of conventional PETG composites, such as poor stiffness and limited fibre–matrix adhesion. The overall objective is to contribute towards the advancement of sustainable materials in additive manufacturing, enabling environmentally friendly and structurally efficient bio-composites suitable for engineering and structural applications.
The hybrid PETG composites were fabricated using the fused filament fabrication process. The methodology began with the preparation of SBF through cleaning, alkali treatment, and silane coupling to improve surface roughness and adhesion with the polymer matrix. CSA was converted into nano-scale particles via controlled carbonization, calcination, high-energy ball milling and ultrasonic dispersion to achieve fine particle size and uniform morphology. Composite formulations were prepared at a fixed 70:30 volume ratio of PETG to reinforcement (SBF + CSA-n), and filaments were produced through twin-screw extrusion. Standardized specimens were 3D printed using optimized process parameters and tested for tensile, flexural, impact and hardness properties according to ASTM standards. Scanning electron microscopy was used to analyse fibre–matrix interaction, filler dispersion and fracture characteristics, supported by quantitative image analysis to assess void content and alignment.
The experimental results demonstrated that the incorporation of nano-scale CSA substantially enhanced the interfacial bonding, mechanical strength and filler dispersion of PETG-based composites. Among all the developed specimens, the hybrid composite containing SBFs and nano-CSA (Specimen D) exhibited superior performance, with tensile strength of 54.1 MPa, flexural strength of 74.8 MPa, impact toughness of 5.6 kJ/m², and hardness of 101 HRM. SEM analysis revealed dense fibre distribution, minimal void formation and strong interfacial adhesion in the nano-CSA-reinforced composites, confirming efficient stress transfer and structural integrity. In contrast, fibre-only composites showed poor adhesion and higher porosity, while micro-CSA-filled composites presented moderate improvements but exhibited uneven filler dispersion. Overall, the findings confirm that the synergistic interaction of SBFs and nano-scale CSA leads to significant gains in stiffness, strength and toughness without compromising printability or weight efficiency.
To the best of the authors’ knowledge, this study is the first to report the development of a 3D-printed hybrid PETG composite reinforced simultaneously with SBF and nano-scale CSA . The novelty lies in demonstrating the synergistic effect of natural fibre and nano-filler reinforcement in enhancing interfacial bonding, load transfer and overall composite performance. Unlike previous single-reinforcement PETG composites, this hybrid system introduces a dual mechanism that significantly improves both mechanical and thermal stability, contributing to the design of next-generation bio-based engineering materials. The research holds substantial value for advancing sustainable additive manufacturing practices by using renewable bamboo fibres and waste-derived nano-fillers, thereby supporting circular economy initiatives and offering a scalable pathway towards environmentally responsible, high-performance composite materials.
