Unleashing the Power of Bio-based Thermotropic Liquid Crystal Modifiers: Toughening and Reinforcing Petroleum-based Epoxy Resin without Compromising Other Properties

Abstract

Toughening the petroleum-based epoxy resin blends with bio-based modifiers without compromising their modulus, mechanical strength, and other properties is still a big challenge in view of the sustainability. In this study, a bio-based liquid crystal epoxy resin (THMT-EP) with an s-triazine ring structure was utilized to modify a petroleum-based bisphenol A epoxy resin (E51) with 4,4′-diaminodiphenylsulfone (DDS) as a curing agent, and the blended systems were evaluated for their thermal stability, mechanical properties, and flame retardancy. The results showed that the impact strength of the blended system initially increased and then decreased with the increase in THMT-EP content, and it reached the a maximum value of 26.5 kJ/m² when the THMT-EP content was 5%, which was 31.2% higher than that of E51/DDS. Notably, the flexural strength, modulus, and glass transition temperature of the blended system were all simultaneously improved with the addition of THMT-EP. At the same time, the addition of THMT-EP enhanced the flame retardancy of the system by increasing the char yield at 700 °C and decreasing the peak heat release rate and total heat release rate. This work paves the way for a more sustainable improvement in the comprehensive performance of epoxy resin.