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

Abstract

AbstractThe 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 (Tg). 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 cm2). This biobased functional reactive modifier has provided balanced overall performance and would pave the way to a wide range of possible “eco‐friendly” applications.