Lignin-based silicone-modified epoxy resin with enhanced strength and toughness

Epoxy composites with enhanced strength and toughness are vital in the field of electronic packaging material. This study proposes the synthesis of a novel lignin-based silicone-modified epoxy resin (LSE) to improve the strength and toughness of epoxy resins (EPs) simultaneously. The results demonstrate that the glass transition temperature, β-relaxation temperature, and crosslinking density of the composites decreased with increasing LSE content. Compared to neat EP, the toughness properties, including the impact strength and critical stress intensity factor (K1C), of the 3 wt% LSE/EP composite improved by 16.25 % and 25.28 %, respectively. Meanwhile, the mechanical properties such as the tensile strength, bending modulus, and bending strength enhanced by 25.81 %, 16.21 %, and 42.43 %, respectively. Therefore, the LSE simultaneously exhibits toughening and strengthening effects. Based on the fracture surface evaluation results obtained using a scanning electron microscope and a nano-FTIR, these effects are attributed to the formation of interpenetrated networks and improved interfacial effects by the LSE. As an efficient fortifier and flexibilizer, LSE shows great promise for the preparation of EP packaging materials.