Improving the degradability of epoxy resin with enhanced mechanical properties via hydrothermal carbon microspheres

The limited degradability and high production costs associated with traditional epoxy resin pose obstacles to its sustainable development. In this study, hybrid material of epoxidized soybean oil-derived epoxy resin (ESOR) and hydrothermal carbon microspheres (HTCs) was designed. Investigations confirmed the presence of diverse oxygen-containing groups on the HTCs, with the carboxyl content specially increased through air activation, which also increased the specific surface area. These alterations enhanced the interfacial interactions between HTCs and ESOR. As a result, the optimized composite exhibited the most notable tensile strength of 3.91 MPa, approximately 22.6 % higher than that of the pure ESOR. Importantly, the incorporation of the air-activated HTCs, which had the water holding and cation exchange capabilities, significantly enhanced the degradability of the ESOR matrix, about 68.3 wt% and 100.0 wt% of the ESOR decomposed respectively from 5HTC300/ESOR and 7 HTC300/ESOR immersed in 0.5 wt% NaOH for 15 day, without the use of organic solvents. While applying the composite materials in coated fertilizers with a 0.5 wt% paraffin outer layer, the best one can slowly release 47.7 % P in 20 days.