Role of carbon quantum dots from lychee fruit husk waste and discarded caster bean stem fiber on load bearing, fatigue, and water uptake properties of epoxy composite

In the pursuit of sustainable materials and enhanced composite performance, this study explores the novel incorporation of carbon quantum dots (CQDs) derived from lychee fruit husk waste and discarded castor bean stem fiber into epoxy composites. The effects of these environmentally friendly additives on the load-bearing capacity, fatigue resistance, and water uptake properties of epoxy composites were systematically investigated. These functional additives were incorporated into the epoxy matrix in varying concentrations such as CQDs of 0.25, 0.5, 1.0, and 2.0 vol% and castor bean stem fiber of 30 vol%. From the results, it is noted that composite designation C4 exhibits higher tensile strength of 152 MPa, the flexural strength of 202 MPa, and impact energy of 5.66 J whereas composite C5 exhibits higher hardness of 94 Shore D. Moreover, C4 composite records improved fatigue life cycle counts of 27,144 for 30% UTS, 23,942 for 60% UTS, and 20,036 for 90% UTS. The increment in CQDs vol% results in increased water absorption such that composite designation C5 records 0.328 water absorption percentage. This study demonstrates the potential of utilizing CQDs and castor bean stem fiber as reinforcements for epoxy composites, enhancing performance and addressing sustainability concerns by repurposing agricultural waste. It contributes to eco-friendly material research and highlights the benefits of novel carbon-based additives in polymer composites, paving the way for more sustainable material solutions.