Cardanol‐Based Epoxy Monomers for High Thermal Properties Thermosets

Abstract

In this paper, epoxy‐anhydride networks are synthesized from a new product of Cardolite Corporation: the Cardolite GX‐2551 epoxy monomer. Due to the complexity of the GX‐2551 structure, an NMR study is performed first to characterize this new commercial product. This epoxy monomer is then reacted with an anhydride (MHHPA) to form polyepoxide thermosets. After curing, dynamic mechanical and thermal analyses are performed for the different thermosets, and then the results are compared to each other. Practical Applications: The cardanol‐derived epoxy monomer described in this contribution, i.e., fully epoxidized molecular cardanol, is a new fully biobased monomer for further epoxy thermoset synthesis. The resulting polyepoxide networks exhibit much higher thermo‐mechanical properties than previous cardanol‐derived epoxy thermosets. Two cardanol‐based epoxy monomers are fully characterized. The GX2551 is reported for the first time and exhibits a higher renewable carbon content. Both monomers are reacted with hexahydro‐4‐methylphtalic anhydride to yield bio‐based aromatic polyepoxide networks with interesting mechanical and thermal properties.

Thermosetting polymers from renewable sources

“…As mentioned previously, cardanol can be used as a precursor for bio‐based epoxy resins 113 . Along these lines, cardanol‐derived epoxides have been used for the preparation of bio‐based epoxy‐anhydride networks 116 and regular epoxy resins with good coating properties 117 …”

Stimuli‐responsive mechanical properties in polymer glasses: challenges and opportunities for defense applications

“…214,215 Increased concentration of crosslinks and free dangling ends promoted this vitrimer-like behavior without the need for high catalyst loadings. In the past couple of years, others have adapted the original epoxy-alcohol vitrimers to bio-based systems with higher amounts of crosslinks by incorporating multifunctional epoxies with other multifunctional alcohol or anhydride [216][217][218][219] or amine crosslinking groups. [220][221][222][223][224] Overall, these systems resulted in reversible, recyclable, high-T g dynamic polymer networks synthesized from renewable resources with the goal of increasing the operational windows of bio-based systems.…”

Bio‐based epoxy‐anhydride thermosets from multi‐armed cardanol‐derived epoxy oligomers

“…The incorporation of the resulting SCNER into BPA‐derived epoxy resins significantly improved their impact strengths 29 . Caillol et al reported epoxy‐anhydride thermosets from epoxidized CGE and MHHPA, which displayed a T g of 126°C 30 . Despite the diverse examples of using cardanol‐based compounds, the thermal and mechanical properties of cardanol‐derived thermosets remain inferior to traditional BPA‐derived counterparts.…”