Tragacanth gum as a green compatibilizer for natural fiber-polymer interfaces in hybrid composites

Astragalus plant is a natural source of tragacanth gum (TG), a polysaccharide that has been investigated as a new green compatibilizer for polymer composites. Unlike traditional petrochemical-based coupling agents, it serves many purposes in improving fiber–matrix bonding and promoting nanofiller dispersion. A tragacanth gum and bentonite nanoclay-modified vinyl ester resin (TGV) matrix was used in this study to create hybrid composites by combining glass fibers with natural fibers (kapok, cotton, and luffa). An L9 orthogonal array was used in Minitab 17 to enhance mechanical properties using Grey Relational Taguchi Analysis (GRTA). There was very little variation between the expected and actual grey relational grades. There was only a slight percentage variation between the actual and forecasted values' trends, which are very similar. The deviation on average was only 4.15 %. SEM examination verified that the TG-based bionanocomposites had enhanced interfacial adhesion. The untreated K/G/K fiber mat composites reinforced with TGV and 3 vol% nanoclay performed the best among the investigated configurations, demonstrating an impact strength of 28 kJ/m² and a tensile strength of 89.1 MPa. These findings demonstrated the multifunctional role of the TG as an eco-friendly compatibilizer, enabling the design of sustainable, high-performance bionanocomposites.