Mechanical Properties of Vinyl Ester Based Sisal and Glass Fiber Composite Material: A Comprehensive Research Study

Abstract

Hybrid fiber-reinforced polymer (FRP) composites combining natural and synthetic fibers offer a promising balance between mechanical performance and environmental sustainability. This research paper examines the mechanical properties of vinyl ester–based sisal/glass fiber hybrid composites, including tensile strength, flexural properties, and impact behavior. Comprehensive comparisons with conventional glass/vinyl ester composites, natural fiber–only systems, and epoxy-based alternatives are provided, along with detailed cost-performance and life-cycle analysis. Data from recent literature demonstrates that optimized hybrids can achieve tensile strengths of 135–150 MPa, flexural strengths of 160–172 MPa, and impact strengths of 11–12 kJ/m², making them suitable for secondary structural applications while reducing material costs and environmental impact by 20–30% compared to fully synthetic systems. This paper synthesizes experimental findings, provides illustrative tables and graph descriptions, and offers guidance for selection of sisal/glass vinyl ester composites in automotive, marine, and civil engineering applications.

Introduction

The text provides a comprehensive review of vinyl ester–based sisal/glass fiber hybrid composites, highlighting their potential as cost-effective and environmentally sustainable alternatives to conventional glass fiber–reinforced polymer (FRP) systems. FRP composites are widely used due to their high strength-to-weight ratio and corrosion resistance, and vinyl ester resins are particularly attractive matrices because of their good mechanical performance, chemical resistance, and ease of processing.

Sisal fibers, derived from Agave sisalana, are renewable, lightweight, and biodegradable but suffer from moisture sensitivity and weaker interfacial bonding with polymer matrices. Hybridizing sisal with glass fibers in a vinyl ester matrix combines the strength and stiffness of glass fibers with the low cost, reduced density, and sustainability of sisal. Alkali treatment of sisal fibers significantly improves fiber–matrix adhesion and mechanical performance. Various hybridization strategies—such as layered laminates, intermingled plies, and skin–core architectures—are discussed to optimize strength, stiffness, impact resistance, and cost.

The paper reviews fabrication methods including hand lay-up and resin transfer molding (RTM), outlining their advantages, limitations, and suitability for different production scales. Mechanical properties such as tensile, flexural, impact, compression, shear, and fatigue behavior are analyzed based on literature data. Results show that sisal/glass hybrid composites can achieve 80–90% of the mechanical performance of all-glass composites while offering better impact energy absorption and reduced density. Optimal performance is typically observed at balanced sisal–glass ratios, especially for impact resistance.

Comparisons with all-glass and all-sisal composites demonstrate that hybrids provide a favorable balance between performance, cost, and environmental impact. While epoxy-based hybrids offer higher absolute mechanical properties, vinyl ester systems are more economical and better suited for high-volume manufacturing. Cost and life-cycle analyses reveal significant reductions in raw material cost, embodied energy, greenhouse gas emissions, and component weight when glass fibers are partially replaced with sisal.

Finally, the text outlines application areas such as automotive panels, marine interior components, and semi-structural parts, where sisal/glass/vinyl ester hybrids deliver weight savings, cost reduction, improved acoustic damping, and enhanced sustainability. Overall, the review concludes that vinyl ester–based sisal/glass hybrid composites represent a technically viable and economically attractive solution for sustainable engineering applications.

Conclusion

1) Performance: Vinyl ester–based sisal/glass fiber hybrid composites provide a promising balance between mechanical performance and sustainability. Tensile strengths of 135–160 MPa, flexural strengths of 160–180 MPa, and impact strengths of 11–12 kJ/m² at optimized hybrid ratios (20S/20G or 10S/30G) make them suitable for secondary structural applications in automotive, marine, and building sectors.[44] 2) Cost advantage: Material and manufacturing cost savings of 25–40% compared to all-glass/vinyl ester systems, combined with weight reductions of 20–25%, provide compelling economics for high-volume applications and long-service-life products (vehicles, appliances).[45] 3) Environmental merit: Life-cycle assessment data demonstrate 40–60% reductions in embodied energy and greenhouse gas emissions for hybrids vs. all-glass systems, with additional benefits from natural fiber biodegradability and carbon sequestration.[46] 4) Comparison with alternatives: While all-glass/vinyl ester and glass/epoxy systems achieve higher absolute mechanical properties, vinyl ester/sisal–glass hybrids offer superior cost-performance and sustainability trade-offs. For design-critical, high-temperature, or maritime applications, pure glass systems remain preferred; for automotive, interior building panels, and semi-structural components, hybrids are increasingly competitive.[47] 5) Future directions: Research should focus on: o Improving fiber–matrix interface through advanced surface treatments and bio-based coupling agents. o Investigating long-term environmental durability (water absorption, fatigue, UV resistance). o Optimizing stacking sequences and architecture for specific applications. o Developing sustainable resin matrices (bio-based vinyl esters) to complement natural fiber reinforcement. o Scaling manufacturing processes (RTM, infusion) to enable industrial adoption in automotive and consumer products.

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Copyright © 2025 Revathy Mohan. 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.