Synthesis and property study of novel maleimide-cardanol based modifiers for epoxy resins

The biomass-based chemicals from renewable resources are countermeasures to ease the problem of fossil fuel shortage. This work is to develop a biobased functional reactive modifier for thermosetting epoxy resins appropriate for excellent overall performance. The novel maleimide-cardanol modifiers (CA-HPM) is synthesized from natural extract cardanol (CA) and N -(4-hydroxyphenyl) maleimide (HPM), which is then mixed with phenolic epoxy resin and linear phenolic novolac resin systems. CA-HPM plays a versatile role in tuning the comprehensive properties of epoxy such as thermal property, adhesive property, and thermo-mechanical property. Systems with CA-HPM show slightly lower curing activity and distinct decreased single glass transition temperature ( T g ). Besides, the crosslinking density of the cured resin increases, meanwhile the thermal stability keeps at high level, which is due to the rigid five-membered ring structure of maleimide. Metal lap shear test results manifest that the adhesion between epoxy resin and metal interface augments. With 10% CA-1HPM, the cured resin exhibits lower equilibrium water sorption (1.88%) and diffusion coefficient (2.94 × 10 −8 s −1 cm 2 ). This biobased functional reactive modifier has provided balanced overall performance and would pave the way to a wide range of possible “eco-friendly” applications.