Mechanical and thermal properties of cotton/bamboo/glass fiber reinforced hybrid epoxy composites for high performance applications

In recent years, natural fiber reinforced composites have gained considerable attention of industries and researchers due to their sustainability, lightweight and cost-effectiveness. This study explores the mechanical and thermal performance of cotton/bamboo/glass (C/B/G) fiber-reinforced hybrid epoxy composites fabricated via hand lay-up and compression molding with a focus on how fiber pre-treatment and chemical bonding mechanisms impact their properties. From the test results of carbon/glass (C/G), bamboo/glass (B/G) and cotton/bamboo/glass (C/B/G) fiber reinforced composites, it is observed that the C/B/G hybrid composite demonstrated superior results. This laminate attained a tensile strength of 121.82 MPa, which is 12.72% and 6.93% higher than that of C/G and B/G composites, respectively. Similarly, it gave the highest flexural strength of 145.73 MPa, impact strength of 58.37 kJ/m² (approximately 1.18% that of others) and compressive strength of 116.82 MPa, which is 6.47% higher than C/G (109.72 MPa) and 317.93% higher than B/G (28 MPa) composites. Furthermore, C/B/G showed the best interlaminar shear strength of 32.96 MPa, outperforming C/G (23.52 MPa) and B/G (27.21 MPa). Shore D hardness of the C/B/G composite was 11% and 19% higher than C/G and B/G, respectively. Thermogravimetric analysis confirmed enhanced thermal stability, with 98% mass retention at 294.4 °C and final degradation at 438.9 °C. Despite a higher moisture absorption rate of 13.76%, compared to C/G (3.54%) and B/G (7.53%), the hybrid composite maintained structural integrity as supported by SEM and XRD analysis. These findings highlight hybrid natural-synthetic composites (C/B/G) as promising candidates for structural and thermal applications in automotive, aerospace and construction sectors, balancing performance with sustainability.