Development of a novel vinyl ester composite reinforced with dragon fruit tree stem fiber and Napier grass cellulose and its performance evaluation

The present research focuses on the development of vinyl ester based hybrid composites reinforced with dragon fruit tree stem fiber and Napier grass derived cellulose, emphasizing improved mechanical performance through enhanced fiber matrix interfacial adhesion and efficient stress transfer mechanisms. The composites were fabricated using the hand layup method in accordance with ASTM standards and evaluated for mechanical, shear, water absorption, and machinability properties. The optimized composite VDC1 containing 3 vol.% cellulose, 30 vol.% dragon fruit stem fiber, and 67 vol.% vinyl ester matrix exhibited superior performance with tensile strength of 168 MPa, flexural strength of 178 MPa, impact strength of 4.9 J, Shore D hardness of 85, and lap shear strength of 35.1 MPa. These improvements are attributed to strong interfacial bonding, effective load transfer, and microstructural reinforcement provided by cellulose and natural fibers, which restrict crack propagation and enhance structural integrity. In contrast, neat vinyl ester resin showed the lowest water absorption (3.5%) and better machinability due to its dense crosslinked structure. SEM analysis further confirmed improved fiber matrix interaction and reduced void formation in optimized composites. The use of dragon fruit stem fiber and Napier grass cellulose offers a sustainable approach for valorising agricultural waste into value added reinforcement materials. The developed composites demonstrate potential for lightweight structural applications in automotive, marine, and packaging sectors due to their balanced mechanical performance and environmental sustainability.