A Review of Coconut Shell Powder as a Reinforcement Composite for Sustainable Abrasive Jet Machining

Abstract

Researchers are looking to incorporate agro-waste products into composite systems as a result of the need for environmentally friendly resources in sophisticated production processes. A lignocellulosic by-product of processing coconuts, coconut shell powder (CSP) has become a popular and environmentally responsible filler for reinforcing polymers. The application of CSP-reinforced composites in Abrasive Jet Machining (AJM), an unusual machining technique renowned for its accuracy and low heat effect, is the main topic of this review paper. Rich in cellulose, hemicellulose, and lignin, CSP\'s composition offers favorable mechanical qualities such enhanced tensile, flexural, and wear resistance when it is included into polymer matrices. It is also a sustainable substitute for traditional fillers due to its hardness, biodegradability, and thermal stability. When CSP is added to epoxy, HDPE, and polyester matrices, the literature shows encouraging results, including improvements in strength, modulus, and machinability. Its function in AJM is still not well understood, though. By combining the results of previous research on CSP-reinforced composites and analyzing their potential for AJM applications, this work seeks to advance green engineering and circular economy principles in material removal procedures.

Introduction

Coconut Shell Powder (CSP), derived from lignocellulosic agro-waste, is gaining attention as a sustainable reinforcement for polymer composites due to its:

• Abundance (from 54+ billion coconuts annually),

• Biodegradability, and

• Mechanical strength.

Its use supports green engineering and the circular economy, particularly in industries seeking eco-friendly materials.

???? Material Characteristics of CSP

1. Composition:

• Cellulose (25–35%), Lignin (30–35%), and Hemicellulose (20–25%)

• Low ash content (0.5–2%) → minimal residue

• Mohs hardness: 2–3 → suitable for wear applications

2. Physical Properties:

• Density: 1.2–1.5 g/cm³ (lighter than mineral fillers)

• Particle size: 50–300 µm (nano- and micro-sizes enhance performance)

• Moisture absorption: 5–10% → requires pre-drying

3. Thermal Properties:

• Degrades at ~200–250°C (suitable for polymer processing)

• Lignin acts as a flame retardant → self-extinguishing potential

???? Mechanical Performance in Composites

• Reinforcement of Polymers: Epoxy, HDPE, polypropylene, polyester

• Strength Improvements:

  • Tensile/Flexural/Impact Strength ↑ up to 25–32%

  • Hardness ↑ up to 30%

  • Wear resistance enhanced due to lignin and hardness

• Optimal CSP content: 10–15% (too much reduces performance)

• Nano-CSP (<100 nm) improves strength further

• Chemical Treatments (e.g., NaOH, silane) boost bonding with polymers

????? Applications

???? General Applications:

• Construction (eco-bricks, lightweight concrete)

• Automotive (brake pads, interiors)

• Packaging and circuit boards

• Soil stabilization (reduces plasticity, increases load-bearing)

???? In Abrasive Jet Machining (AJM):

• Potential applications:

  • Reinforced nozzles

  • Fixture substrates

  • Possibly as a green abrasive (not yet tested directly)

• CSP composites show good surface integrity, erosion resistance, and material removal rates

• Hybrid CSP composites (with coir, tamarind shell, rice husk) perform better in wear settings

???? Research Methods Summary

CSP Processing:

• Cleaning → Drying → Grinding → Sieving (75–150 µm)

• Optional chemical surface treatments for better adhesion

Composite Fabrication Techniques:

• Hand lay-up

• Compression molding

• Extrusion molding

Characterization Tools:

• SEM, XRF, EDX for morphology and elemental analysis

• Mechanical testing (ASTM): tensile, flexural, impact

• Thermal analysis, water absorption, and surface roughness tests

AJM-Specific Studies:

• No direct use of CSP as abrasive

• Optimization via Taguchi and Response Surface Methodology (RSM) explored for similar natural fiber composites

? Key Takeaways

• CSP is a highly promising, sustainable filler for polymer composites with excellent mechanical, thermal, and wear properties.

• It is especially suited for abrasion-prone components, making it a candidate for Abrasive Jet Machining applications, though direct research is limited.

• Further studies could explore:

  • Use of CSP as an actual abrasive

  • Nano-CSP effects

  • Advanced surface treatments

  • Optimization of AJM parameters (pressure, standoff, grit size)

Conclusion

According to this review, coconut shell powder (CSP) is a very efficient and environmentally friendly reinforcing ingredient for polymer matrix composites. According to several studies, CSP can greatly increase hardness, impact resistance, tensile strength, and flexural strength, particularly when applied in the range of 10% to 15% by weight [5-13]. It is a good choice for high-performance applications because of its natural composition, which is rich in cellulose and lignin, as well as its comparatively high hardness and abrasion resistance. CSP\'s potential for long-term and structural applications is further enhanced by its capacity to decrease water absorption and enhance dimensional stability [16]. Existing research indicates that CSP-based composites perform well under erosion and surface wear, which are crucial in AJM environments, despite the fact that CSP has not yet been extensively investigated in direct abrasive jet machining (AJM) applications [7-19]. Because of this, they could be helpful in AJM setups for producing nozzles, workpiece holders, shields, or even protective layers. Additionally, CSP is an environmentally benign substitute for synthetic fillers due to its low cost, widespread availability, and biodegradable nature, which supports the objectives of green and sustainable manufacturing. In conclusion, there are economic, ecological, and mechanical benefits to using coconut shell powder. Its effectiveness in enhancing composite qualities and its potential for erosion-based applications provide compelling evidence for its application in AJM-related domains. CSP has the potential to be a key element of future sustainable machining systems, lowering environmental impact while preserving functional performance, with more focused study and testing.

References

[1] Adarsh, M. K., Manjunatha, H., & Devaraju, R. (2022). Coconut shell powder reinforced epoxy composites: A review. Agricultural Reviews, 43(1), 98–103. https://doi.org/10.18805/ag.R-2114 [2] Aradhyula, T. V., Chandra, T. S. S., Reddy, B. S., Chauhan, R. N., Ramakrishna, M., & Murthy, C. (2015). Coconut shell powder for composite to improve the mechanical properties. International Journal of Mechanical and Production Engineering, 3(9), 7–8. [3] Ismail, I., Arliyani, Z., Jalil, M., Mursal, Olaiya, N. G., Abdullah, C. K., Fazita, M. R. N., & Khalil, H. P. S. A. (2020). Properties and characterization of new approach organic nanoparticle-based biocomposite board. Polymers, 12(10), 2236. https://doi.org/10.3390/polym12102236 [4] Kirby, M., Lewis, B., Peterson, B., Anggono, J., & Bradley, W. (2019). The effect of coconut shell powder as functional filler in polypropylene during compounding and subsequent molding. E3S Web of Conferences, 130, 01021. https://doi.org/10.1051/e3sconf/201913001021 [5] Nayak, S. Y., Shenoy, S. B., Kini, C. R., Sultan, M. T. H., & Shahar, F. S. (2022). Experimental investigation into mechanical properties of coconut shell powder modified epoxy/3D E-glass composites. Engineered Science, 20, 306–320. https://doi.org/10.30919/es8e759 [6] Preeti, Mohod, A. G., Khandetod, Y. P., Dhande, K. G., & Sawant, P. A. (2024). Physico-chemical characterization of coconut shell (Cocos nucifera). International Journal of Advanced Biochemistry Research, 8(3), 118–122. https://doi.org/10.33545/26174693.2024.v8.i3Sb.703 [7] Reddy, M. V. R., Viswanath, K., & Reddy, K. P. K. (2020). Fabrication and study the effect of mechanical properties of coconut shell powder and rice husk. International Journal of Trend in Scientific Research and Development (IJTSRD), 4(5), 1013–1015. [8] Somashekhar, T. M., Naik, P., Nayak, V., Mallikappa, & Rahul, S. (2018). Study of mechanical properties of coconut shell powder and tamarind shell powder reinforced with epoxy composites. IOP Conference Series: Materials Science and Engineering, 376(1), 012105. https://doi.org/10.1088/1757-899X/376/1/012105 [9] Triadi, A. A. A., & Darmo, S. (2021). Characterization of mechanical properties of composite materials with filler coconut shell powder and sawdust with coconut fiber reinforcement as an alternative to low loaded brake friction materials. Global Journal of Engineering and Technology Advances, https://doi.org/10.30574/gjeta.2021.9.2.0148 [10] Vasu, A. T., Reddy, C., Danaboyina, S., Manchala, G. K., & Chavali, M. (2017). The improvement in mechanical properties of coconut shell powder as filler in HDPE composites. Journal of Polymer Science & Applications, 1(2), 1–6. https://doi.org/10.4172/2471-9935.1000104 [11] Andezai, A. M., Masu, L. M., & Maringa, M. (2020). Chemical and morphological characterization of coconut shell powder, epoxy resin and CSP/epoxy resin composites. International Journal of Engineering Research and Technology, 13(12), 4269–4275. [12] Anbua, E. T., Dandakouta, H., Bawa, M. A., & Tokan, A. (2024). A comparative study of elemental compositions of coconut shell powder and coconut coir ash for selective applications. International Journal of Research Publication and Reviews, https://doi.org/10.55248/gengpi.5.0124.0265 [13] Dhas, J. E. R., et al. (2022). Effect of coconut shell nanopowder reinforcement in the development of palm fiber composites. Frontiers in Materials, 9, 986011. https://doi.org/10.3389/fmats.2022.986011 [14] Herlina Sari, N., et al. (2021). Morphology and mechanical properties of coconut shell powder-filled untreated cornhusk fibre-unsaturated polyester composites. Polymer, 222, https://doi.org/10.1016/j.polymer.2021.123657 [15] Manu, A. S., et al. (2024). Experimental investigation on effect of coconut shell powder on index properties of lime treated black cotton soil. Nanotechnology Perceptions, 20(2), 130–138. [16] Obiukwu, O. O., et al. (2016). Study on the properties of coconut shell powder reinforced high-density polyethylene composite. FUTO Journal Series, 2(2), 43–55. [17] Sharma, A., Singh, D., & Gupta, R. (2021). Optimization of abrasive jet machining parameters on natural fiber composites using Taguchi method. Materials Today: Proceedings, https://doi.org/10.1016/j.matpr.2020.10.173 [18] Verma, B., et al. (2022). Experimental study on light weight concrete using coconut shell and fly ash. International Journal for Research in Applied Science and Engineering Technology, https://doi.org/10.22214/ijraset.2022.39896 [19] Vignesh, K., Natarajan, U., & Vijayasekar, A. (2019). Wear behaviour of coconut shell powder and coir fibre reinforced polyester composites. IOSR Journal of Mechanical and Civil Engineering, 53–57.

Copyright

Copyright © 2025 Aditya Chaudhary, Rohit Srivastava, Anurag Shrivastava. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.